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#41
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Receiver Prob - Loose left channel at low volume
In , on 12/13/03
at 05:34 AM, "Mark D. Zacharias" said: Just don't be too surprised if the amp blows up. The technique may indeed work - but consider the common light bulb. At power-on or power-off is the most common time for it to fail. Sudden application or removal of voltage causes current surges, and output transistors change their physical characteristics a bit from thermal expansion/contracting as the piece warms up and cools down. This is normal wear and tear to be sure, but be aware you may be accelerating the process significantly. Mark Z. Repeat 30 times. At this point, I'll bet your problem is gone. If the amplifier is otherwise healthy, it's no worse than a sudden bass note. You only need to play the amp at these volume levels for a fraction of a second. If you start cold, even after the 30 repetitions, the amp only warms up to a regular working temperature. If you are worried about the temperature rise, wait 30 seconds between repetitions. I've been using this trick for decades and haven't lost any units. (I have a fully equipped test bench and check the amplifiers afterward -- there's never been a problem.) Initially, everyone blinks and squints a bit when I describe this technique. Most, particularly engineers, like the idea and add it to their bag of tricks. If you are really bothered about the turn-on surge, unsolder one leg of the protection relay coil and flash the contacts by pulsing the relay. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#42
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Receiver Prob - Loose left channel at low volume
In , on 12/13/03
at 05:34 AM, "Mark D. Zacharias" said: Just don't be too surprised if the amp blows up. The technique may indeed work - but consider the common light bulb. At power-on or power-off is the most common time for it to fail. Sudden application or removal of voltage causes current surges, and output transistors change their physical characteristics a bit from thermal expansion/contracting as the piece warms up and cools down. This is normal wear and tear to be sure, but be aware you may be accelerating the process significantly. Mark Z. Repeat 30 times. At this point, I'll bet your problem is gone. If the amplifier is otherwise healthy, it's no worse than a sudden bass note. You only need to play the amp at these volume levels for a fraction of a second. If you start cold, even after the 30 repetitions, the amp only warms up to a regular working temperature. If you are worried about the temperature rise, wait 30 seconds between repetitions. I've been using this trick for decades and haven't lost any units. (I have a fully equipped test bench and check the amplifiers afterward -- there's never been a problem.) Initially, everyone blinks and squints a bit when I describe this technique. Most, particularly engineers, like the idea and add it to their bag of tricks. If you are really bothered about the turn-on surge, unsolder one leg of the protection relay coil and flash the contacts by pulsing the relay. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#43
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Receiver Prob - Loose left channel at low volume
In , on 12/13/03
at 05:34 AM, "Mark D. Zacharias" said: Just don't be too surprised if the amp blows up. The technique may indeed work - but consider the common light bulb. At power-on or power-off is the most common time for it to fail. Sudden application or removal of voltage causes current surges, and output transistors change their physical characteristics a bit from thermal expansion/contracting as the piece warms up and cools down. This is normal wear and tear to be sure, but be aware you may be accelerating the process significantly. Mark Z. Repeat 30 times. At this point, I'll bet your problem is gone. If the amplifier is otherwise healthy, it's no worse than a sudden bass note. You only need to play the amp at these volume levels for a fraction of a second. If you start cold, even after the 30 repetitions, the amp only warms up to a regular working temperature. If you are worried about the temperature rise, wait 30 seconds between repetitions. I've been using this trick for decades and haven't lost any units. (I have a fully equipped test bench and check the amplifiers afterward -- there's never been a problem.) Initially, everyone blinks and squints a bit when I describe this technique. Most, particularly engineers, like the idea and add it to their bag of tricks. If you are really bothered about the turn-on surge, unsolder one leg of the protection relay coil and flash the contacts by pulsing the relay. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#44
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Receiver Prob - Loose left channel at low volume
There's been a couple threads lately involving units damged by repeated
power on-off cycling, usually by children. Mark Z. -- Please reply only to Group. I regret this is necessary. Viruses and spam have rendered my regular e-mail address useless. "Barry Mann" wrote in message om... In , on 12/13/03 at 05:34 AM, "Mark D. Zacharias" said: Just don't be too surprised if the amp blows up. The technique may indeed work - but consider the common light bulb. At power-on or power-off is the most common time for it to fail. Sudden application or removal of voltage causes current surges, and output transistors change their physical characteristics a bit from thermal expansion/contracting as the piece warms up and cools down. This is normal wear and tear to be sure, but be aware you may be accelerating the process significantly. Mark Z. Repeat 30 times. At this point, I'll bet your problem is gone. If the amplifier is otherwise healthy, it's no worse than a sudden bass note. You only need to play the amp at these volume levels for a fraction of a second. If you start cold, even after the 30 repetitions, the amp only warms up to a regular working temperature. If you are worried about the temperature rise, wait 30 seconds between repetitions. I've been using this trick for decades and haven't lost any units. (I have a fully equipped test bench and check the amplifiers afterward -- there's never been a problem.) Initially, everyone blinks and squints a bit when I describe this technique. Most, particularly engineers, like the idea and add it to their bag of tricks. If you are really bothered about the turn-on surge, unsolder one leg of the protection relay coil and flash the contacts by pulsing the relay. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#45
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Receiver Prob - Loose left channel at low volume
There's been a couple threads lately involving units damged by repeated
power on-off cycling, usually by children. Mark Z. -- Please reply only to Group. I regret this is necessary. Viruses and spam have rendered my regular e-mail address useless. "Barry Mann" wrote in message om... In , on 12/13/03 at 05:34 AM, "Mark D. Zacharias" said: Just don't be too surprised if the amp blows up. The technique may indeed work - but consider the common light bulb. At power-on or power-off is the most common time for it to fail. Sudden application or removal of voltage causes current surges, and output transistors change their physical characteristics a bit from thermal expansion/contracting as the piece warms up and cools down. This is normal wear and tear to be sure, but be aware you may be accelerating the process significantly. Mark Z. Repeat 30 times. At this point, I'll bet your problem is gone. If the amplifier is otherwise healthy, it's no worse than a sudden bass note. You only need to play the amp at these volume levels for a fraction of a second. If you start cold, even after the 30 repetitions, the amp only warms up to a regular working temperature. If you are worried about the temperature rise, wait 30 seconds between repetitions. I've been using this trick for decades and haven't lost any units. (I have a fully equipped test bench and check the amplifiers afterward -- there's never been a problem.) Initially, everyone blinks and squints a bit when I describe this technique. Most, particularly engineers, like the idea and add it to their bag of tricks. If you are really bothered about the turn-on surge, unsolder one leg of the protection relay coil and flash the contacts by pulsing the relay. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#46
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Receiver Prob - Loose left channel at low volume
There's been a couple threads lately involving units damged by repeated
power on-off cycling, usually by children. Mark Z. -- Please reply only to Group. I regret this is necessary. Viruses and spam have rendered my regular e-mail address useless. "Barry Mann" wrote in message om... In , on 12/13/03 at 05:34 AM, "Mark D. Zacharias" said: Just don't be too surprised if the amp blows up. The technique may indeed work - but consider the common light bulb. At power-on or power-off is the most common time for it to fail. Sudden application or removal of voltage causes current surges, and output transistors change their physical characteristics a bit from thermal expansion/contracting as the piece warms up and cools down. This is normal wear and tear to be sure, but be aware you may be accelerating the process significantly. Mark Z. Repeat 30 times. At this point, I'll bet your problem is gone. If the amplifier is otherwise healthy, it's no worse than a sudden bass note. You only need to play the amp at these volume levels for a fraction of a second. If you start cold, even after the 30 repetitions, the amp only warms up to a regular working temperature. If you are worried about the temperature rise, wait 30 seconds between repetitions. I've been using this trick for decades and haven't lost any units. (I have a fully equipped test bench and check the amplifiers afterward -- there's never been a problem.) Initially, everyone blinks and squints a bit when I describe this technique. Most, particularly engineers, like the idea and add it to their bag of tricks. If you are really bothered about the turn-on surge, unsolder one leg of the protection relay coil and flash the contacts by pulsing the relay. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#47
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Receiver Prob - Loose left channel at low volume
In , on 12/13/03
at 11:01 PM, "Mark D. Zacharias" said: There's been a couple threads lately involving units damged by repeated power on-off cycling, usually by children. It's not an issue. If you cycle fast enough, the filter capacitors will not discharge completely and the turn-on transient will be smaller than for a normal turn-on. The major "risk" is for the power switch, which will be carrying more current at the instant of turn off than if the unit had been idling at the time of shutdown. (unfortunately, it was years of soft shutdowns that caused the protection relay to get into trouble in the first place.) If 30 extra power switch cycles are offensive, then apply my treatment once a day for thirty days being careful to perform the procedure only once at the end of the listening day. That way there are no extra power cycles over the life of the unit and the unit will have plenty of time to cool off. Even though the situation may improve after the first day, I recommend continuing for the full 30 days. --- Anyone who feels uncomfortable with the procedure should not attempt it. For everyone else, you'll find it works like a charm. The down side is that, if you have misdiagnosed the fundamental problem or the relay is seriously burned, the technique won't accomplish anything and you'll squander about four minutes of your life. This is not a procedure I apply to every unit that crosses my bench. The problem described at the beginning of this thread is a classic protection relay issue that is usually resolved after using my technique. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#48
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Receiver Prob - Loose left channel at low volume
In , on 12/13/03
at 11:01 PM, "Mark D. Zacharias" said: There's been a couple threads lately involving units damged by repeated power on-off cycling, usually by children. It's not an issue. If you cycle fast enough, the filter capacitors will not discharge completely and the turn-on transient will be smaller than for a normal turn-on. The major "risk" is for the power switch, which will be carrying more current at the instant of turn off than if the unit had been idling at the time of shutdown. (unfortunately, it was years of soft shutdowns that caused the protection relay to get into trouble in the first place.) If 30 extra power switch cycles are offensive, then apply my treatment once a day for thirty days being careful to perform the procedure only once at the end of the listening day. That way there are no extra power cycles over the life of the unit and the unit will have plenty of time to cool off. Even though the situation may improve after the first day, I recommend continuing for the full 30 days. --- Anyone who feels uncomfortable with the procedure should not attempt it. For everyone else, you'll find it works like a charm. The down side is that, if you have misdiagnosed the fundamental problem or the relay is seriously burned, the technique won't accomplish anything and you'll squander about four minutes of your life. This is not a procedure I apply to every unit that crosses my bench. The problem described at the beginning of this thread is a classic protection relay issue that is usually resolved after using my technique. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#49
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Receiver Prob - Loose left channel at low volume
In , on 12/13/03
at 11:01 PM, "Mark D. Zacharias" said: There's been a couple threads lately involving units damged by repeated power on-off cycling, usually by children. It's not an issue. If you cycle fast enough, the filter capacitors will not discharge completely and the turn-on transient will be smaller than for a normal turn-on. The major "risk" is for the power switch, which will be carrying more current at the instant of turn off than if the unit had been idling at the time of shutdown. (unfortunately, it was years of soft shutdowns that caused the protection relay to get into trouble in the first place.) If 30 extra power switch cycles are offensive, then apply my treatment once a day for thirty days being careful to perform the procedure only once at the end of the listening day. That way there are no extra power cycles over the life of the unit and the unit will have plenty of time to cool off. Even though the situation may improve after the first day, I recommend continuing for the full 30 days. --- Anyone who feels uncomfortable with the procedure should not attempt it. For everyone else, you'll find it works like a charm. The down side is that, if you have misdiagnosed the fundamental problem or the relay is seriously burned, the technique won't accomplish anything and you'll squander about four minutes of your life. This is not a procedure I apply to every unit that crosses my bench. The problem described at the beginning of this thread is a classic protection relay issue that is usually resolved after using my technique. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#50
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Receiver Prob - Loose left channel at low volume
In many cases it is a residual small dc offset, and/or high-volume music
present when the relay "hits" or when it's disengaged, which caused the relay problem in the first place. I assumed this fix was for situations where it was impractical to remove and service the relay. If it's on the bench anyway, I would simply remove it and service it properly, assuming that was possible. Mark Z. -- Please reply only to Group. I regret this is necessary. Viruses and spam have rendered my regular e-mail address useless. "Barry Mann" wrote in message om... In , on 12/13/03 at 11:01 PM, "Mark D. Zacharias" said: There's been a couple threads lately involving units damged by repeated power on-off cycling, usually by children. It's not an issue. If you cycle fast enough, the filter capacitors will not discharge completely and the turn-on transient will be smaller than for a normal turn-on. The major "risk" is for the power switch, which will be carrying more current at the instant of turn off than if the unit had been idling at the time of shutdown. (unfortunately, it was years of soft shutdowns that caused the protection relay to get into trouble in the first place.) If 30 extra power switch cycles are offensive, then apply my treatment once a day for thirty days being careful to perform the procedure only once at the end of the listening day. That way there are no extra power cycles over the life of the unit and the unit will have plenty of time to cool off. Even though the situation may improve after the first day, I recommend continuing for the full 30 days. --- Anyone who feels uncomfortable with the procedure should not attempt it. For everyone else, you'll find it works like a charm. The down side is that, if you have misdiagnosed the fundamental problem or the relay is seriously burned, the technique won't accomplish anything and you'll squander about four minutes of your life. This is not a procedure I apply to every unit that crosses my bench. The problem described at the beginning of this thread is a classic protection relay issue that is usually resolved after using my technique. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#51
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Receiver Prob - Loose left channel at low volume
In many cases it is a residual small dc offset, and/or high-volume music
present when the relay "hits" or when it's disengaged, which caused the relay problem in the first place. I assumed this fix was for situations where it was impractical to remove and service the relay. If it's on the bench anyway, I would simply remove it and service it properly, assuming that was possible. Mark Z. -- Please reply only to Group. I regret this is necessary. Viruses and spam have rendered my regular e-mail address useless. "Barry Mann" wrote in message om... In , on 12/13/03 at 11:01 PM, "Mark D. Zacharias" said: There's been a couple threads lately involving units damged by repeated power on-off cycling, usually by children. It's not an issue. If you cycle fast enough, the filter capacitors will not discharge completely and the turn-on transient will be smaller than for a normal turn-on. The major "risk" is for the power switch, which will be carrying more current at the instant of turn off than if the unit had been idling at the time of shutdown. (unfortunately, it was years of soft shutdowns that caused the protection relay to get into trouble in the first place.) If 30 extra power switch cycles are offensive, then apply my treatment once a day for thirty days being careful to perform the procedure only once at the end of the listening day. That way there are no extra power cycles over the life of the unit and the unit will have plenty of time to cool off. Even though the situation may improve after the first day, I recommend continuing for the full 30 days. --- Anyone who feels uncomfortable with the procedure should not attempt it. For everyone else, you'll find it works like a charm. The down side is that, if you have misdiagnosed the fundamental problem or the relay is seriously burned, the technique won't accomplish anything and you'll squander about four minutes of your life. This is not a procedure I apply to every unit that crosses my bench. The problem described at the beginning of this thread is a classic protection relay issue that is usually resolved after using my technique. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#52
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Receiver Prob - Loose left channel at low volume
In many cases it is a residual small dc offset, and/or high-volume music
present when the relay "hits" or when it's disengaged, which caused the relay problem in the first place. I assumed this fix was for situations where it was impractical to remove and service the relay. If it's on the bench anyway, I would simply remove it and service it properly, assuming that was possible. Mark Z. -- Please reply only to Group. I regret this is necessary. Viruses and spam have rendered my regular e-mail address useless. "Barry Mann" wrote in message om... In , on 12/13/03 at 11:01 PM, "Mark D. Zacharias" said: There's been a couple threads lately involving units damged by repeated power on-off cycling, usually by children. It's not an issue. If you cycle fast enough, the filter capacitors will not discharge completely and the turn-on transient will be smaller than for a normal turn-on. The major "risk" is for the power switch, which will be carrying more current at the instant of turn off than if the unit had been idling at the time of shutdown. (unfortunately, it was years of soft shutdowns that caused the protection relay to get into trouble in the first place.) If 30 extra power switch cycles are offensive, then apply my treatment once a day for thirty days being careful to perform the procedure only once at the end of the listening day. That way there are no extra power cycles over the life of the unit and the unit will have plenty of time to cool off. Even though the situation may improve after the first day, I recommend continuing for the full 30 days. --- Anyone who feels uncomfortable with the procedure should not attempt it. For everyone else, you'll find it works like a charm. The down side is that, if you have misdiagnosed the fundamental problem or the relay is seriously burned, the technique won't accomplish anything and you'll squander about four minutes of your life. This is not a procedure I apply to every unit that crosses my bench. The problem described at the beginning of this thread is a classic protection relay issue that is usually resolved after using my technique. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#53
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Receiver Prob - Loose left channel at low volume
In , on 12/14/03
at 06:39 AM, "Mark D. Zacharias" said: In many cases it is a residual small dc offset, and/or high-volume music present when the relay "hits" or when it's disengaged, which caused the relay problem in the first place. Unless the offset is high enough to cause some contact heating, I claim that the offset will tend to prevent or minimize the problem. Most people turn down the volume before turning off the unit. Essentially, this is operating the relay in the "dry" region, but it was never designed to operate there. Speaker relays should be operated such that there is enough current flowing at break time to burn off the contact surface contamination. If the relay continually opens without any significant current to break, it's only a matter of time till the contact becomes intermittent. Yes, I can imagine seriously burned contacts becoming a problem, but I've never observed it. The problem relays I encounter have been chronically starved for current at break time. I assumed this fix was for situations where it was impractical to remove and service the relay. If it's on the bench anyway, I would simply remove it and service it properly, assuming that was possible. Yes, if the customer will pay for it. Many times they'll call, barely able to communicate this (to them) bizarre behavior, and I'll have the customer do my procedure at home. You can argue that I will lose some immediate income, but they will remember that I treated them well, saved them the bother of a nuisance service call, and they'll be back later and/or recommend me to their friends. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#54
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Receiver Prob - Loose left channel at low volume
In , on 12/14/03
at 06:39 AM, "Mark D. Zacharias" said: In many cases it is a residual small dc offset, and/or high-volume music present when the relay "hits" or when it's disengaged, which caused the relay problem in the first place. Unless the offset is high enough to cause some contact heating, I claim that the offset will tend to prevent or minimize the problem. Most people turn down the volume before turning off the unit. Essentially, this is operating the relay in the "dry" region, but it was never designed to operate there. Speaker relays should be operated such that there is enough current flowing at break time to burn off the contact surface contamination. If the relay continually opens without any significant current to break, it's only a matter of time till the contact becomes intermittent. Yes, I can imagine seriously burned contacts becoming a problem, but I've never observed it. The problem relays I encounter have been chronically starved for current at break time. I assumed this fix was for situations where it was impractical to remove and service the relay. If it's on the bench anyway, I would simply remove it and service it properly, assuming that was possible. Yes, if the customer will pay for it. Many times they'll call, barely able to communicate this (to them) bizarre behavior, and I'll have the customer do my procedure at home. You can argue that I will lose some immediate income, but they will remember that I treated them well, saved them the bother of a nuisance service call, and they'll be back later and/or recommend me to their friends. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#55
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Receiver Prob - Loose left channel at low volume
In , on 12/14/03
at 06:39 AM, "Mark D. Zacharias" said: In many cases it is a residual small dc offset, and/or high-volume music present when the relay "hits" or when it's disengaged, which caused the relay problem in the first place. Unless the offset is high enough to cause some contact heating, I claim that the offset will tend to prevent or minimize the problem. Most people turn down the volume before turning off the unit. Essentially, this is operating the relay in the "dry" region, but it was never designed to operate there. Speaker relays should be operated such that there is enough current flowing at break time to burn off the contact surface contamination. If the relay continually opens without any significant current to break, it's only a matter of time till the contact becomes intermittent. Yes, I can imagine seriously burned contacts becoming a problem, but I've never observed it. The problem relays I encounter have been chronically starved for current at break time. I assumed this fix was for situations where it was impractical to remove and service the relay. If it's on the bench anyway, I would simply remove it and service it properly, assuming that was possible. Yes, if the customer will pay for it. Many times they'll call, barely able to communicate this (to them) bizarre behavior, and I'll have the customer do my procedure at home. You can argue that I will lose some immediate income, but they will remember that I treated them well, saved them the bother of a nuisance service call, and they'll be back later and/or recommend me to their friends. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#56
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Receiver Prob - Loose left channel at low volume
Barry could this be done with just using an old pair of headphones {not on
the head of course }? Is the speaker relay in the cct when headphones are plugged in ? |
#57
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Receiver Prob - Loose left channel at low volume
Barry could this be done with just using an old pair of headphones {not on
the head of course }? Is the speaker relay in the cct when headphones are plugged in ? |
#58
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Receiver Prob - Loose left channel at low volume
Barry could this be done with just using an old pair of headphones {not on
the head of course }? Is the speaker relay in the cct when headphones are plugged in ? |
#59
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Receiver Prob - Loose left channel at low volume
In , on 12/15/03
at 11:34 AM, "dickydoo" said: Barry could this be done with just using an old pair of headphones {not on the head of course }? Is the speaker relay in the cct when headphones are plugged in ? It won't be effective. The relay contacts must be carrying significant current at the instant they open. The technique will usually work if you connect the amplifier to a high powered eight or four Ohm resistor, but it will work better when connected to speakers. Headphones draw very little current. Usually, but not always, the headphone jack is connected at the same point (after the relay) as the speakers. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#60
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Receiver Prob - Loose left channel at low volume
In , on 12/15/03
at 11:34 AM, "dickydoo" said: Barry could this be done with just using an old pair of headphones {not on the head of course }? Is the speaker relay in the cct when headphones are plugged in ? It won't be effective. The relay contacts must be carrying significant current at the instant they open. The technique will usually work if you connect the amplifier to a high powered eight or four Ohm resistor, but it will work better when connected to speakers. Headphones draw very little current. Usually, but not always, the headphone jack is connected at the same point (after the relay) as the speakers. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#61
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Receiver Prob - Loose left channel at low volume
In , on 12/15/03
at 11:34 AM, "dickydoo" said: Barry could this be done with just using an old pair of headphones {not on the head of course }? Is the speaker relay in the cct when headphones are plugged in ? It won't be effective. The relay contacts must be carrying significant current at the instant they open. The technique will usually work if you connect the amplifier to a high powered eight or four Ohm resistor, but it will work better when connected to speakers. Headphones draw very little current. Usually, but not always, the headphone jack is connected at the same point (after the relay) as the speakers. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#62
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Receiver Prob - Loose left channel at low volume
Okay, thanks.
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#63
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Receiver Prob - Loose left channel at low volume
Okay, thanks.
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#64
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Receiver Prob - Loose left channel at low volume
Okay, thanks.
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#65
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Receiver Prob - Loose left channel at low volume
I think you've got it backwards here. High current when the circuit is
broken causes inevitable sparking, thus pitting and carbonization. Sometimes the contacts actually weld together under extreme conditions. Age and oxidation cause the bad connections you speak of, not lack of current flow when the relay closes or opens. Besides, the technique you describe must take some time to accomplish - removing the relay for proper service probably wouldn't take any longer. Mark Z. Speaker relays should be operated such that there is enough current flowing at break time to burn off the contact surface contamination. -- Please reply only to Group. I regret this is necessary. Viruses and spam have rendered my regular e-mail address useless. "Barry Mann" wrote in message om... In , on 12/14/03 at 06:39 AM, "Mark D. Zacharias" said: In many cases it is a residual small dc offset, and/or high-volume music present when the relay "hits" or when it's disengaged, which caused the relay problem in the first place. Unless the offset is high enough to cause some contact heating, I claim that the offset will tend to prevent or minimize the problem. Most people turn down the volume before turning off the unit. Essentially, this is operating the relay in the "dry" region, but it was never designed to operate there. Speaker relays should be operated such that there is enough current flowing at break time to burn off the contact surface contamination. If the relay continually opens without any significant current to break, it's only a matter of time till the contact becomes intermittent. Yes, I can imagine seriously burned contacts becoming a problem, but I've never observed it. The problem relays I encounter have been chronically starved for current at break time. I assumed this fix was for situations where it was impractical to remove and service the relay. If it's on the bench anyway, I would simply remove it and service it properly, assuming that was possible. Yes, if the customer will pay for it. Many times they'll call, barely able to communicate this (to them) bizarre behavior, and I'll have the customer do my procedure at home. You can argue that I will lose some immediate income, but they will remember that I treated them well, saved them the bother of a nuisance service call, and they'll be back later and/or recommend me to their friends. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#66
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Receiver Prob - Loose left channel at low volume
I think you've got it backwards here. High current when the circuit is
broken causes inevitable sparking, thus pitting and carbonization. Sometimes the contacts actually weld together under extreme conditions. Age and oxidation cause the bad connections you speak of, not lack of current flow when the relay closes or opens. Besides, the technique you describe must take some time to accomplish - removing the relay for proper service probably wouldn't take any longer. Mark Z. Speaker relays should be operated such that there is enough current flowing at break time to burn off the contact surface contamination. -- Please reply only to Group. I regret this is necessary. Viruses and spam have rendered my regular e-mail address useless. "Barry Mann" wrote in message om... In , on 12/14/03 at 06:39 AM, "Mark D. Zacharias" said: In many cases it is a residual small dc offset, and/or high-volume music present when the relay "hits" or when it's disengaged, which caused the relay problem in the first place. Unless the offset is high enough to cause some contact heating, I claim that the offset will tend to prevent or minimize the problem. Most people turn down the volume before turning off the unit. Essentially, this is operating the relay in the "dry" region, but it was never designed to operate there. Speaker relays should be operated such that there is enough current flowing at break time to burn off the contact surface contamination. If the relay continually opens without any significant current to break, it's only a matter of time till the contact becomes intermittent. Yes, I can imagine seriously burned contacts becoming a problem, but I've never observed it. The problem relays I encounter have been chronically starved for current at break time. I assumed this fix was for situations where it was impractical to remove and service the relay. If it's on the bench anyway, I would simply remove it and service it properly, assuming that was possible. Yes, if the customer will pay for it. Many times they'll call, barely able to communicate this (to them) bizarre behavior, and I'll have the customer do my procedure at home. You can argue that I will lose some immediate income, but they will remember that I treated them well, saved them the bother of a nuisance service call, and they'll be back later and/or recommend me to their friends. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#67
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Receiver Prob - Loose left channel at low volume
I think you've got it backwards here. High current when the circuit is
broken causes inevitable sparking, thus pitting and carbonization. Sometimes the contacts actually weld together under extreme conditions. Age and oxidation cause the bad connections you speak of, not lack of current flow when the relay closes or opens. Besides, the technique you describe must take some time to accomplish - removing the relay for proper service probably wouldn't take any longer. Mark Z. Speaker relays should be operated such that there is enough current flowing at break time to burn off the contact surface contamination. -- Please reply only to Group. I regret this is necessary. Viruses and spam have rendered my regular e-mail address useless. "Barry Mann" wrote in message om... In , on 12/14/03 at 06:39 AM, "Mark D. Zacharias" said: In many cases it is a residual small dc offset, and/or high-volume music present when the relay "hits" or when it's disengaged, which caused the relay problem in the first place. Unless the offset is high enough to cause some contact heating, I claim that the offset will tend to prevent or minimize the problem. Most people turn down the volume before turning off the unit. Essentially, this is operating the relay in the "dry" region, but it was never designed to operate there. Speaker relays should be operated such that there is enough current flowing at break time to burn off the contact surface contamination. If the relay continually opens without any significant current to break, it's only a matter of time till the contact becomes intermittent. Yes, I can imagine seriously burned contacts becoming a problem, but I've never observed it. The problem relays I encounter have been chronically starved for current at break time. I assumed this fix was for situations where it was impractical to remove and service the relay. If it's on the bench anyway, I would simply remove it and service it properly, assuming that was possible. Yes, if the customer will pay for it. Many times they'll call, barely able to communicate this (to them) bizarre behavior, and I'll have the customer do my procedure at home. You can argue that I will lose some immediate income, but they will remember that I treated them well, saved them the bother of a nuisance service call, and they'll be back later and/or recommend me to their friends. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#68
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Receiver Prob - Loose left channel at low volume
In , on 12/14/03
at 05:49 PM, "Mark D. Zacharias" said: I think you've got it backwards here. High current when the circuit is broken causes inevitable sparking, I want that "sparking". Sparking is what cleans the relay contact. This type of relay demands a certain amount of arcing to keep the contact surfaces in good shape. Very low current relays (less than about 5mA) don't arc and can be gold plated so they won't develop this sort of problem. One could use gold plated contacts on speaker relays, but the first time the customer opens the relay with speaker current flowing, the gold will be blown away and we'll be stuck with the underlying base metal contacts. Sometimes relay contacts will be thinly plated with gold to keep the contacts clean during initial storage, but it is expected to be blown away after interrupting any significant current. thus pitting and carbonization. Sometimes the contacts actually weld together under extreme conditions. Age and oxidation cause the bad connections you speak of, not lack of current flow when the relay closes or opens. Of course, too much arcing will cause damage. Yes, age and oxidation cause the intermittent contact, but a little arcing will burn the oxidation off the surface. Some relays are designed to "wipe" (a bit of rubbing during the make and break) and help scrape the surfaces clean. I'm sure there are some burnt relay contacts out there. But, even though I think most consumer amplifiers use wimpy relays, I've never seen any burned or welded relay contacts on otherwise healthy consumer amplifiers. The contacts on relays I've opened and cleaned look perfect. Besides, the technique you describe must take some time to accomplish - removing the relay for proper service probably wouldn't take any longer. Assuming the turn-on delay is about 8 seconds, the whole procedure takes about 4 minutes. The big disadvantage is that your power switch operating finger or thumb might get tired. If I've already got the unit open, it is about the same or a little less time for me to flip the unit over, unsolder one leg of the relay coil, flash the relay and have it soldered back together. Maybe I'm slow, but it would take much longer for me to fetch or order a relay, pull the old one, and insert a new one. Add a bit more time if the unit is not open. Sometimes one must remove a board or two before the speaker protection relay is accessible. For the customer it's a big time saver if they don't even have to take the unit off the shelf and bring it in. ---- Another failure mode of relays (especially the low current type) is outgassing of the relay's own case contaminating the contact surface. (my technique will clear this coating too) --- I try to promote self help for my customers. About a week ago I had a very frustrated long time customer call me and start to describe a wildly intermittant problem with a certain unit. It fit a known pattern and I have another cute little home cure for that one. I told him what to do and by the end of our seven minute conversation the unit was fixed. I bumped into him on the street a few days later -- he's a happy camper. You would probably grumble about this trick too, but I started using it about ten years ago and haven't had any call backs. -- And my little trick is not nearly as stressful on the unit as disassembling it and applying the obvious fix. (we also avoid a parts ordering delay) ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#69
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Receiver Prob - Loose left channel at low volume
In , on 12/14/03
at 05:49 PM, "Mark D. Zacharias" said: I think you've got it backwards here. High current when the circuit is broken causes inevitable sparking, I want that "sparking". Sparking is what cleans the relay contact. This type of relay demands a certain amount of arcing to keep the contact surfaces in good shape. Very low current relays (less than about 5mA) don't arc and can be gold plated so they won't develop this sort of problem. One could use gold plated contacts on speaker relays, but the first time the customer opens the relay with speaker current flowing, the gold will be blown away and we'll be stuck with the underlying base metal contacts. Sometimes relay contacts will be thinly plated with gold to keep the contacts clean during initial storage, but it is expected to be blown away after interrupting any significant current. thus pitting and carbonization. Sometimes the contacts actually weld together under extreme conditions. Age and oxidation cause the bad connections you speak of, not lack of current flow when the relay closes or opens. Of course, too much arcing will cause damage. Yes, age and oxidation cause the intermittent contact, but a little arcing will burn the oxidation off the surface. Some relays are designed to "wipe" (a bit of rubbing during the make and break) and help scrape the surfaces clean. I'm sure there are some burnt relay contacts out there. But, even though I think most consumer amplifiers use wimpy relays, I've never seen any burned or welded relay contacts on otherwise healthy consumer amplifiers. The contacts on relays I've opened and cleaned look perfect. Besides, the technique you describe must take some time to accomplish - removing the relay for proper service probably wouldn't take any longer. Assuming the turn-on delay is about 8 seconds, the whole procedure takes about 4 minutes. The big disadvantage is that your power switch operating finger or thumb might get tired. If I've already got the unit open, it is about the same or a little less time for me to flip the unit over, unsolder one leg of the relay coil, flash the relay and have it soldered back together. Maybe I'm slow, but it would take much longer for me to fetch or order a relay, pull the old one, and insert a new one. Add a bit more time if the unit is not open. Sometimes one must remove a board or two before the speaker protection relay is accessible. For the customer it's a big time saver if they don't even have to take the unit off the shelf and bring it in. ---- Another failure mode of relays (especially the low current type) is outgassing of the relay's own case contaminating the contact surface. (my technique will clear this coating too) --- I try to promote self help for my customers. About a week ago I had a very frustrated long time customer call me and start to describe a wildly intermittant problem with a certain unit. It fit a known pattern and I have another cute little home cure for that one. I told him what to do and by the end of our seven minute conversation the unit was fixed. I bumped into him on the street a few days later -- he's a happy camper. You would probably grumble about this trick too, but I started using it about ten years ago and haven't had any call backs. -- And my little trick is not nearly as stressful on the unit as disassembling it and applying the obvious fix. (we also avoid a parts ordering delay) ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#70
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Receiver Prob - Loose left channel at low volume
In , on 12/14/03
at 05:49 PM, "Mark D. Zacharias" said: I think you've got it backwards here. High current when the circuit is broken causes inevitable sparking, I want that "sparking". Sparking is what cleans the relay contact. This type of relay demands a certain amount of arcing to keep the contact surfaces in good shape. Very low current relays (less than about 5mA) don't arc and can be gold plated so they won't develop this sort of problem. One could use gold plated contacts on speaker relays, but the first time the customer opens the relay with speaker current flowing, the gold will be blown away and we'll be stuck with the underlying base metal contacts. Sometimes relay contacts will be thinly plated with gold to keep the contacts clean during initial storage, but it is expected to be blown away after interrupting any significant current. thus pitting and carbonization. Sometimes the contacts actually weld together under extreme conditions. Age and oxidation cause the bad connections you speak of, not lack of current flow when the relay closes or opens. Of course, too much arcing will cause damage. Yes, age and oxidation cause the intermittent contact, but a little arcing will burn the oxidation off the surface. Some relays are designed to "wipe" (a bit of rubbing during the make and break) and help scrape the surfaces clean. I'm sure there are some burnt relay contacts out there. But, even though I think most consumer amplifiers use wimpy relays, I've never seen any burned or welded relay contacts on otherwise healthy consumer amplifiers. The contacts on relays I've opened and cleaned look perfect. Besides, the technique you describe must take some time to accomplish - removing the relay for proper service probably wouldn't take any longer. Assuming the turn-on delay is about 8 seconds, the whole procedure takes about 4 minutes. The big disadvantage is that your power switch operating finger or thumb might get tired. If I've already got the unit open, it is about the same or a little less time for me to flip the unit over, unsolder one leg of the relay coil, flash the relay and have it soldered back together. Maybe I'm slow, but it would take much longer for me to fetch or order a relay, pull the old one, and insert a new one. Add a bit more time if the unit is not open. Sometimes one must remove a board or two before the speaker protection relay is accessible. For the customer it's a big time saver if they don't even have to take the unit off the shelf and bring it in. ---- Another failure mode of relays (especially the low current type) is outgassing of the relay's own case contaminating the contact surface. (my technique will clear this coating too) --- I try to promote self help for my customers. About a week ago I had a very frustrated long time customer call me and start to describe a wildly intermittant problem with a certain unit. It fit a known pattern and I have another cute little home cure for that one. I told him what to do and by the end of our seven minute conversation the unit was fixed. I bumped into him on the street a few days later -- he's a happy camper. You would probably grumble about this trick too, but I started using it about ten years ago and haven't had any call backs. -- And my little trick is not nearly as stressful on the unit as disassembling it and applying the obvious fix. (we also avoid a parts ordering delay) ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#71
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Receiver Prob - Loose left channel at low volume
Almost all speaker relays used in consumer equipment use gold-plated
contacts, and have for years. Additionally, modern surround receivers mostly don't have sound going out all the various channels during a test procedure on the bench. If the piece doesn't have 6-ch. inputs, and many don't, then you'll have to mess around with a mono signal for the center channel, stereo for the left and right channels, L-R for the surround, at sufficient volume to give you your desired sparking effect, I presume 30 or so times each. That's up to 90 power on-off cycles, assuming LR front and surround each get one 30-cycle treatment. Maybe your finger or thumb WOULD get tired. Mark Z. -- Please reply only to Group. I regret this is necessary. Viruses and spam have rendered my regular e-mail address useless. "Barry Mann" wrote in message om... In , on 12/14/03 at 05:49 PM, "Mark D. Zacharias" said: I think you've got it backwards here. High current when the circuit is broken causes inevitable sparking, I want that "sparking". Sparking is what cleans the relay contact. This type of relay demands a certain amount of arcing to keep the contact surfaces in good shape. Very low current relays (less than about 5mA) don't arc and can be gold plated so they won't develop this sort of problem. One could use gold plated contacts on speaker relays, but the first time the customer opens the relay with speaker current flowing, the gold will be blown away and we'll be stuck with the underlying base metal contacts. Sometimes relay contacts will be thinly plated with gold to keep the contacts clean during initial storage, but it is expected to be blown away after interrupting any significant current. thus pitting and carbonization. Sometimes the contacts actually weld together under extreme conditions. Age and oxidation cause the bad connections you speak of, not lack of current flow when the relay closes or opens. Of course, too much arcing will cause damage. Yes, age and oxidation cause the intermittent contact, but a little arcing will burn the oxidation off the surface. Some relays are designed to "wipe" (a bit of rubbing during the make and break) and help scrape the surfaces clean. I'm sure there are some burnt relay contacts out there. But, even though I think most consumer amplifiers use wimpy relays, I've never seen any burned or welded relay contacts on otherwise healthy consumer amplifiers. The contacts on relays I've opened and cleaned look perfect. Besides, the technique you describe must take some time to accomplish - removing the relay for proper service probably wouldn't take any longer. Assuming the turn-on delay is about 8 seconds, the whole procedure takes about 4 minutes. The big disadvantage is that your power switch operating finger or thumb might get tired. If I've already got the unit open, it is about the same or a little less time for me to flip the unit over, unsolder one leg of the relay coil, flash the relay and have it soldered back together. Maybe I'm slow, but it would take much longer for me to fetch or order a relay, pull the old one, and insert a new one. Add a bit more time if the unit is not open. Sometimes one must remove a board or two before the speaker protection relay is accessible. For the customer it's a big time saver if they don't even have to take the unit off the shelf and bring it in. ---- Another failure mode of relays (especially the low current type) is outgassing of the relay's own case contaminating the contact surface. (my technique will clear this coating too) --- I try to promote self help for my customers. About a week ago I had a very frustrated long time customer call me and start to describe a wildly intermittant problem with a certain unit. It fit a known pattern and I have another cute little home cure for that one. I told him what to do and by the end of our seven minute conversation the unit was fixed. I bumped into him on the street a few days later -- he's a happy camper. You would probably grumble about this trick too, but I started using it about ten years ago and haven't had any call backs. -- And my little trick is not nearly as stressful on the unit as disassembling it and applying the obvious fix. (we also avoid a parts ordering delay) ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#72
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Receiver Prob - Loose left channel at low volume
Almost all speaker relays used in consumer equipment use gold-plated
contacts, and have for years. Additionally, modern surround receivers mostly don't have sound going out all the various channels during a test procedure on the bench. If the piece doesn't have 6-ch. inputs, and many don't, then you'll have to mess around with a mono signal for the center channel, stereo for the left and right channels, L-R for the surround, at sufficient volume to give you your desired sparking effect, I presume 30 or so times each. That's up to 90 power on-off cycles, assuming LR front and surround each get one 30-cycle treatment. Maybe your finger or thumb WOULD get tired. Mark Z. -- Please reply only to Group. I regret this is necessary. Viruses and spam have rendered my regular e-mail address useless. "Barry Mann" wrote in message om... In , on 12/14/03 at 05:49 PM, "Mark D. Zacharias" said: I think you've got it backwards here. High current when the circuit is broken causes inevitable sparking, I want that "sparking". Sparking is what cleans the relay contact. This type of relay demands a certain amount of arcing to keep the contact surfaces in good shape. Very low current relays (less than about 5mA) don't arc and can be gold plated so they won't develop this sort of problem. One could use gold plated contacts on speaker relays, but the first time the customer opens the relay with speaker current flowing, the gold will be blown away and we'll be stuck with the underlying base metal contacts. Sometimes relay contacts will be thinly plated with gold to keep the contacts clean during initial storage, but it is expected to be blown away after interrupting any significant current. thus pitting and carbonization. Sometimes the contacts actually weld together under extreme conditions. Age and oxidation cause the bad connections you speak of, not lack of current flow when the relay closes or opens. Of course, too much arcing will cause damage. Yes, age and oxidation cause the intermittent contact, but a little arcing will burn the oxidation off the surface. Some relays are designed to "wipe" (a bit of rubbing during the make and break) and help scrape the surfaces clean. I'm sure there are some burnt relay contacts out there. But, even though I think most consumer amplifiers use wimpy relays, I've never seen any burned or welded relay contacts on otherwise healthy consumer amplifiers. The contacts on relays I've opened and cleaned look perfect. Besides, the technique you describe must take some time to accomplish - removing the relay for proper service probably wouldn't take any longer. Assuming the turn-on delay is about 8 seconds, the whole procedure takes about 4 minutes. The big disadvantage is that your power switch operating finger or thumb might get tired. If I've already got the unit open, it is about the same or a little less time for me to flip the unit over, unsolder one leg of the relay coil, flash the relay and have it soldered back together. Maybe I'm slow, but it would take much longer for me to fetch or order a relay, pull the old one, and insert a new one. Add a bit more time if the unit is not open. Sometimes one must remove a board or two before the speaker protection relay is accessible. For the customer it's a big time saver if they don't even have to take the unit off the shelf and bring it in. ---- Another failure mode of relays (especially the low current type) is outgassing of the relay's own case contaminating the contact surface. (my technique will clear this coating too) --- I try to promote self help for my customers. About a week ago I had a very frustrated long time customer call me and start to describe a wildly intermittant problem with a certain unit. It fit a known pattern and I have another cute little home cure for that one. I told him what to do and by the end of our seven minute conversation the unit was fixed. I bumped into him on the street a few days later -- he's a happy camper. You would probably grumble about this trick too, but I started using it about ten years ago and haven't had any call backs. -- And my little trick is not nearly as stressful on the unit as disassembling it and applying the obvious fix. (we also avoid a parts ordering delay) ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#73
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Receiver Prob - Loose left channel at low volume
Almost all speaker relays used in consumer equipment use gold-plated
contacts, and have for years. Additionally, modern surround receivers mostly don't have sound going out all the various channels during a test procedure on the bench. If the piece doesn't have 6-ch. inputs, and many don't, then you'll have to mess around with a mono signal for the center channel, stereo for the left and right channels, L-R for the surround, at sufficient volume to give you your desired sparking effect, I presume 30 or so times each. That's up to 90 power on-off cycles, assuming LR front and surround each get one 30-cycle treatment. Maybe your finger or thumb WOULD get tired. Mark Z. -- Please reply only to Group. I regret this is necessary. Viruses and spam have rendered my regular e-mail address useless. "Barry Mann" wrote in message om... In , on 12/14/03 at 05:49 PM, "Mark D. Zacharias" said: I think you've got it backwards here. High current when the circuit is broken causes inevitable sparking, I want that "sparking". Sparking is what cleans the relay contact. This type of relay demands a certain amount of arcing to keep the contact surfaces in good shape. Very low current relays (less than about 5mA) don't arc and can be gold plated so they won't develop this sort of problem. One could use gold plated contacts on speaker relays, but the first time the customer opens the relay with speaker current flowing, the gold will be blown away and we'll be stuck with the underlying base metal contacts. Sometimes relay contacts will be thinly plated with gold to keep the contacts clean during initial storage, but it is expected to be blown away after interrupting any significant current. thus pitting and carbonization. Sometimes the contacts actually weld together under extreme conditions. Age and oxidation cause the bad connections you speak of, not lack of current flow when the relay closes or opens. Of course, too much arcing will cause damage. Yes, age and oxidation cause the intermittent contact, but a little arcing will burn the oxidation off the surface. Some relays are designed to "wipe" (a bit of rubbing during the make and break) and help scrape the surfaces clean. I'm sure there are some burnt relay contacts out there. But, even though I think most consumer amplifiers use wimpy relays, I've never seen any burned or welded relay contacts on otherwise healthy consumer amplifiers. The contacts on relays I've opened and cleaned look perfect. Besides, the technique you describe must take some time to accomplish - removing the relay for proper service probably wouldn't take any longer. Assuming the turn-on delay is about 8 seconds, the whole procedure takes about 4 minutes. The big disadvantage is that your power switch operating finger or thumb might get tired. If I've already got the unit open, it is about the same or a little less time for me to flip the unit over, unsolder one leg of the relay coil, flash the relay and have it soldered back together. Maybe I'm slow, but it would take much longer for me to fetch or order a relay, pull the old one, and insert a new one. Add a bit more time if the unit is not open. Sometimes one must remove a board or two before the speaker protection relay is accessible. For the customer it's a big time saver if they don't even have to take the unit off the shelf and bring it in. ---- Another failure mode of relays (especially the low current type) is outgassing of the relay's own case contaminating the contact surface. (my technique will clear this coating too) --- I try to promote self help for my customers. About a week ago I had a very frustrated long time customer call me and start to describe a wildly intermittant problem with a certain unit. It fit a known pattern and I have another cute little home cure for that one. I told him what to do and by the end of our seven minute conversation the unit was fixed. I bumped into him on the street a few days later -- he's a happy camper. You would probably grumble about this trick too, but I started using it about ten years ago and haven't had any call backs. -- And my little trick is not nearly as stressful on the unit as disassembling it and applying the obvious fix. (we also avoid a parts ordering delay) ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
#74
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Receiver Prob - Loose left channel at low volume
"Barry Mann" wrote in message
om In , on 12/14/03 at 05:49 PM, "Mark D. Zacharias" said: I think you've got it backwards here. High current when the circuit is broken causes inevitable sparking, I want that "sparking". Sparking is what cleans the relay contact. Not necessarily. Most relay contacts are designed, if possible to scrub over each other when they make and break. This does a great job of cleaning the contact, and is also less damaging than arcing. This type of relay demands a certain amount of arcing to keep the contact surfaces in good shape. Very low current relays (less than about 5mA) don't arc and can be gold plated so they won't develop this sort of problem. Agreed, metals like gold, ruthenium, and palladium are used to make or plate relay contacts that handle low currents (less than 50 milliamps). These are called "dry circuit" relays. Dry circuit relays are best hermetically sealed to avoid contamination of the contacts. Dry circuit relays are sometimes used with a "sealing" DC current that essentially biases the relay. This is a kind of a kluge and really shouldn't be necessary with modern relays. One could use gold plated contacts on speaker relays, but the first time the customer opens the relay with speaker current flowing, the gold will be blown away and we'll be stuck with the underlying base metal contacts. Also agreed. Relays for power circuits use silver or proprietary alloys formulated around metals like Tungsten that can take arcing. In either case, wherever possible, relay contacts are designed to scrub over each other as they make and break to get a nice self-cleaning action going. While it all happened over 20 years ago, at the time we did a lot of research into low and high current relays when we were designing and building the ABX Comparator. The low-level relays were ruthenium-plated reed relays, and the high level relays were based on a high temperature proprietary alloy. I haven't seen that much has changed since then, except that solid-state devices are far more commonly used to avoid the use of electromechanical relays. |
#75
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Receiver Prob - Loose left channel at low volume
"Barry Mann" wrote in message
om In , on 12/14/03 at 05:49 PM, "Mark D. Zacharias" said: I think you've got it backwards here. High current when the circuit is broken causes inevitable sparking, I want that "sparking". Sparking is what cleans the relay contact. Not necessarily. Most relay contacts are designed, if possible to scrub over each other when they make and break. This does a great job of cleaning the contact, and is also less damaging than arcing. This type of relay demands a certain amount of arcing to keep the contact surfaces in good shape. Very low current relays (less than about 5mA) don't arc and can be gold plated so they won't develop this sort of problem. Agreed, metals like gold, ruthenium, and palladium are used to make or plate relay contacts that handle low currents (less than 50 milliamps). These are called "dry circuit" relays. Dry circuit relays are best hermetically sealed to avoid contamination of the contacts. Dry circuit relays are sometimes used with a "sealing" DC current that essentially biases the relay. This is a kind of a kluge and really shouldn't be necessary with modern relays. One could use gold plated contacts on speaker relays, but the first time the customer opens the relay with speaker current flowing, the gold will be blown away and we'll be stuck with the underlying base metal contacts. Also agreed. Relays for power circuits use silver or proprietary alloys formulated around metals like Tungsten that can take arcing. In either case, wherever possible, relay contacts are designed to scrub over each other as they make and break to get a nice self-cleaning action going. While it all happened over 20 years ago, at the time we did a lot of research into low and high current relays when we were designing and building the ABX Comparator. The low-level relays were ruthenium-plated reed relays, and the high level relays were based on a high temperature proprietary alloy. I haven't seen that much has changed since then, except that solid-state devices are far more commonly used to avoid the use of electromechanical relays. |
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Receiver Prob - Loose left channel at low volume
"Barry Mann" wrote in message
om In , on 12/14/03 at 05:49 PM, "Mark D. Zacharias" said: I think you've got it backwards here. High current when the circuit is broken causes inevitable sparking, I want that "sparking". Sparking is what cleans the relay contact. Not necessarily. Most relay contacts are designed, if possible to scrub over each other when they make and break. This does a great job of cleaning the contact, and is also less damaging than arcing. This type of relay demands a certain amount of arcing to keep the contact surfaces in good shape. Very low current relays (less than about 5mA) don't arc and can be gold plated so they won't develop this sort of problem. Agreed, metals like gold, ruthenium, and palladium are used to make or plate relay contacts that handle low currents (less than 50 milliamps). These are called "dry circuit" relays. Dry circuit relays are best hermetically sealed to avoid contamination of the contacts. Dry circuit relays are sometimes used with a "sealing" DC current that essentially biases the relay. This is a kind of a kluge and really shouldn't be necessary with modern relays. One could use gold plated contacts on speaker relays, but the first time the customer opens the relay with speaker current flowing, the gold will be blown away and we'll be stuck with the underlying base metal contacts. Also agreed. Relays for power circuits use silver or proprietary alloys formulated around metals like Tungsten that can take arcing. In either case, wherever possible, relay contacts are designed to scrub over each other as they make and break to get a nice self-cleaning action going. While it all happened over 20 years ago, at the time we did a lot of research into low and high current relays when we were designing and building the ABX Comparator. The low-level relays were ruthenium-plated reed relays, and the high level relays were based on a high temperature proprietary alloy. I haven't seen that much has changed since then, except that solid-state devices are far more commonly used to avoid the use of electromechanical relays. |
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Receiver Prob - Loose left channel at low volume
In , on 12/15/03
at 05:53 AM, "Mark D. Zacharias" said: [ ... ] Additionally, modern surround receivers mostly don't have sound going out all the various channels during a test procedure on the bench. If the piece doesn't have 6-ch. inputs, and many don't, then you'll have to mess around with a mono signal for the center channel, stereo for the left and right channels, L-R for the surround, at sufficient volume to give you your desired sparking effect, I presume 30 or so times each. That's up to 90 power on-off cycles, assuming LR front and surround each get one 30-cycle treatment. Maybe your finger or thumb WOULD get tired. Not only would your thumb get tired from the power switch, but you'd have to climb down the test menu again after each power cycle. A/V receivers are more difficult to deal with on all levels. Access to the relays is usually very painful. Fortunately, the original poster complained about the main channels. Some units make my procedure easier because the Speaker A and Speaker B switches key the protection relays. Others make things easier because the Mute function keys all the main room relays. Some recent units (too early for the protection relay syndrum) have a four or six speaker Stereo mode. And, yes, the six channel mode can be useful. Overall, I've had a lot less trouble with the 90's era relays than the 70's and 80's era relays. (Yes, I know, we must be careful evaluating the data because the 90's relays aren't 20 or more years old.) In the 70's I started seeing relay problems after about five years. In the late 80's I started seeing better relay choices. The contacts wipe better and the cases don't degas as much. The poster's unit is one of the few 90's era relay issues I've come across. I'm not in bed with this technique. When appropriate, it's a great time saver. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
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Receiver Prob - Loose left channel at low volume
In , on 12/15/03
at 05:53 AM, "Mark D. Zacharias" said: [ ... ] Additionally, modern surround receivers mostly don't have sound going out all the various channels during a test procedure on the bench. If the piece doesn't have 6-ch. inputs, and many don't, then you'll have to mess around with a mono signal for the center channel, stereo for the left and right channels, L-R for the surround, at sufficient volume to give you your desired sparking effect, I presume 30 or so times each. That's up to 90 power on-off cycles, assuming LR front and surround each get one 30-cycle treatment. Maybe your finger or thumb WOULD get tired. Not only would your thumb get tired from the power switch, but you'd have to climb down the test menu again after each power cycle. A/V receivers are more difficult to deal with on all levels. Access to the relays is usually very painful. Fortunately, the original poster complained about the main channels. Some units make my procedure easier because the Speaker A and Speaker B switches key the protection relays. Others make things easier because the Mute function keys all the main room relays. Some recent units (too early for the protection relay syndrum) have a four or six speaker Stereo mode. And, yes, the six channel mode can be useful. Overall, I've had a lot less trouble with the 90's era relays than the 70's and 80's era relays. (Yes, I know, we must be careful evaluating the data because the 90's relays aren't 20 or more years old.) In the 70's I started seeing relay problems after about five years. In the late 80's I started seeing better relay choices. The contacts wipe better and the cases don't degas as much. The poster's unit is one of the few 90's era relay issues I've come across. I'm not in bed with this technique. When appropriate, it's a great time saver. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
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Receiver Prob - Loose left channel at low volume
In , on 12/15/03
at 05:53 AM, "Mark D. Zacharias" said: [ ... ] Additionally, modern surround receivers mostly don't have sound going out all the various channels during a test procedure on the bench. If the piece doesn't have 6-ch. inputs, and many don't, then you'll have to mess around with a mono signal for the center channel, stereo for the left and right channels, L-R for the surround, at sufficient volume to give you your desired sparking effect, I presume 30 or so times each. That's up to 90 power on-off cycles, assuming LR front and surround each get one 30-cycle treatment. Maybe your finger or thumb WOULD get tired. Not only would your thumb get tired from the power switch, but you'd have to climb down the test menu again after each power cycle. A/V receivers are more difficult to deal with on all levels. Access to the relays is usually very painful. Fortunately, the original poster complained about the main channels. Some units make my procedure easier because the Speaker A and Speaker B switches key the protection relays. Others make things easier because the Mute function keys all the main room relays. Some recent units (too early for the protection relay syndrum) have a four or six speaker Stereo mode. And, yes, the six channel mode can be useful. Overall, I've had a lot less trouble with the 90's era relays than the 70's and 80's era relays. (Yes, I know, we must be careful evaluating the data because the 90's relays aren't 20 or more years old.) In the 70's I started seeing relay problems after about five years. In the late 80's I started seeing better relay choices. The contacts wipe better and the cases don't degas as much. The poster's unit is one of the few 90's era relay issues I've come across. I'm not in bed with this technique. When appropriate, it's a great time saver. ----------------------------------------------------------- spam: wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15 13 (Barry Mann) [sorry about the puzzle, spammers are ruining my mailbox] ----------------------------------------------------------- |
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