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#1
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SSM 2017
I have a home made amp in the workshop which gets heavy use. Since the end
of the last century. It has balanced inputs, and for some reasons lost in the mists of time, I used SSM 2017. Probably because I had loads. On powering up at the end of last week, both had died. It has a +/- 15v regulated PS entirely separate from the power amp - which appears fine. It also feeds the pre-amp, and that is ok. Only odd thing was heavy lightening we had on Thursday night - quite the most spectacular I've seen in London. But the amp was switched off during that - and nothing else in a house full of electronics seems to have suffered. Bit of a mystery. -- *Gravity is a myth, the earth sucks * Dave Plowman London SW To e-mail, change noise into sound. |
#2
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SSM 2017
On Wed, 23 Jul 2014, Dave Plowman (News) wrote:
I have a home made amp in the workshop which gets heavy use. Since the end of the last century. It has balanced inputs, and for some reasons lost in the mists of time, I used SSM 2017. Probably because I had loads. On powering up at the end of last week, both had died. It has a +/- 15v regulated PS entirely separate from the power amp - which appears fine. It also feeds the pre-amp, and that is ok. Only odd thing was heavy lightening we had on Thursday night - quite the most spectacular I've seen in London. But the amp was switched off during that - and nothing else in a house full of electronics seems to have suffered. Bit of a mystery. Do you remember the last time you had it turned on? Maybe it was damaged before being powered off, and you didn't notice. If you get a chance to analyze the problem, it might be interesting to learn what failed. For now, just a guess based on my own recent experience: One thing about the SSM2017 and similar chips is that you need diodes from the inputs to the plus and minus power supplies to protect against transients. (For example, if phantom power for a mic preamp is turned on when the XLR connector is pulled out, the transient that appeas on the chip's inputs is much higher than the absolute maximum rating of the chip.) I had an INA163 chip fail in my M-Audio DMP3, and it was because the designer failed to include four $0.02 diodes per channel to protect the INA163, which cost over $7.50 to replace. The 1N4148 diodes are shown in an example mic preamp circuit in the manufacturer's datasheet, with this included in the discussion: "For additional input protection against ESD and hot-plugging, four INA4148 [sic.] diodes may be connected from the input to supply lines." Perhaps the word "may" was interpreted as permission to omit them. I guess that's what I get for spending only $100 per channel for a mic pre. Fortunately, after I replaced the INA163, adding the diodes was not hard. |
#3
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SSM 2017
On 24/07/2014 4:02 a.m., Dave Plowman (News) wrote:
I have a home made amp in the workshop which gets heavy use. Since the end of the last century. It has balanced inputs, and for some reasons lost in the mists of time, I used SSM 2017. Probably because I had loads. On powering up at the end of last week, both had died. It has a +/- 15v regulated PS entirely separate from the power amp - which appears fine. It also feeds the pre-amp, and that is ok. Only odd thing was heavy lightening we had on Thursday night - quite the most spectacular I've seen in London. But the amp was switched off during that - and nothing else in a house full of electronics seems to have suffered. Bit of a mystery. I generally find TL0xx to be very fragile. geoff |
#4
Posted to rec.audio.pro
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SSM 2017
In article ,
Jay Ts wrote: Do you remember the last time you had it turned on? Maybe it was damaged before being powered off, and you didn't notice. No - it's normally playing the radio. If you get a chance to analyze the problem, it might be interesting to learn what failed. For now, just a guess based on my own recent experience: One thing about the SSM2017 and similar chips is that you need diodes from the inputs to the plus and minus power supplies to protect against transients. (For example, if phantom power for a mic preamp is turned on when the XLR connector is pulled out, the transient that appeas on the chip's inputs is much higher than the absolute maximum rating of the chip.) Yes - I do that when using it as a mic pre-amp. But this is fed at (near) line level. It is also regularly hot plugged when I'm using it to test things with a balanced output. Must have been done hundreds of times without problems. I had an INA163 chip fail in my M-Audio DMP3, and it was because the designer failed to include four $0.02 diodes per channel to protect the INA163, which cost over $7.50 to replace. The 1N4148 diodes are shown in an example mic preamp circuit in the manufacturer's datasheet, with this included in the discussion: "For additional input protection against ESD and hot-plugging, four INA4148 [sic.] diodes may be connected from the input to supply lines." Perhaps the word "may" was interpreted as permission to omit them. I guess that's what I get for spending only $100 per channel for a mic pre. Fortunately, after I replaced the INA163, adding the diodes was not hard. Quite. I have a third one in the same enclosure used as a mic amp with phantom power, for mic testing, and powered from the same PS. It is ok. It does have the diodes. It is in a steel case to help with screening, though. If one had failed I'd have put it down to chance. But both at exactly the same time (and after 15 years or so) is just plain weird, unless the PS had thrown a wobbly. -- *Of course I'm against sin; I'm against anything that I'm too old to enjoy. Dave Plowman London SW To e-mail, change noise into sound. |
#5
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SSM 2017
On 7/23/2014 6:42 PM, Dave Plowman (News) wrote:
If one had failed I'd have put it down to chance. But both at exactly the same time (and after 15 years or so) is just plain weird, unless the PS had thrown a wobbly. You mentioned that there was a thunderstorm prior to your discovering the failure. That could have been the cause. Lightning can induce short term power surges by putting a couple of thousand volts on to the power ground when a lightning bolt hits the earth. That can attack your gear through the power supply even if it's turned off. -- For a good time, visit http://mikeriversaudio.wordpress.com |
#6
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SSM 2017
In article ,
Mike Rivers wrote: On 7/23/2014 6:42 PM, Dave Plowman (News) wrote: If one had failed I'd have put it down to chance. But both at exactly the same time (and after 15 years or so) is just plain weird, unless the PS had thrown a wobbly. You mentioned that there was a thunderstorm prior to your discovering the failure. That could have been the cause. Lightning can induce short term power surges by putting a couple of thousand volts on to the power ground when a lightning bolt hits the earth. That can attack your gear through the power supply even if it's turned off. Yes - it's a nice tidy explanation for the two failing at the same time - after all those years and the replacements are working normally. Although just why these failed when everything else is ok - and it's not the first thunderstorm I've seen here, although one of the most spectacular. -- *Who is this General Failure chap anyway - and why is he reading my HD? * Dave Plowman London SW To e-mail, change noise into sound. |
#7
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SSM 2017
"Dave Plowman (News)" wrote in message
... In article , Mike Rivers wrote: On 7/23/2014 6:42 PM, Dave Plowman (News) wrote: If one had failed I'd have put it down to chance. But both at exactly the same time (and after 15 years or so) is just plain weird, unless the PS had thrown a wobbly. You mentioned that there was a thunderstorm prior to your discovering the failure. That could have been the cause. Lightning can induce short term power surges by putting a couple of thousand volts on to the power ground when a lightning bolt hits the earth. That can attack your gear through the power supply even if it's turned off. Yes - it's a nice tidy explanation for the two failing at the same time - after all those years and the replacements are working normally. Although just why these failed when everything else is ok - and it's not the first thunderstorm I've seen here, although one of the most spectacular. It depends on how close you are to where the lightning goes to ground. A few years back we had a bolt that hit about 50 yards from our home and took out several pieces of gear. Almost took out one of my son's friends who was stupidly playing a video game with a wired controller during the storm. It took a few hours for his arm to recover from the shock. I've always demanded that everything gets unplugged during a lightning storm if possible - and the cord is pulled away from the socket. Had a computer fry when my son unplugged the cord but left it hanging an inch away from the socket - the burn marks on the socket told the story. Sean |
#8
Posted to rec.audio.pro
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SSM 2017
Dave Plowman (News) wrote:
One thing about the SSM2017 and similar chips is that you need diodes from the inputs to the plus and minus power supplies to protect against transients. (For example, if phantom power for a mic preamp is turned on when the XLR connector is pulled out, the transient that appeas on the chip's inputs is much higher than the absolute maximum rating of the chip.) Yes - I do that when using it as a mic pre-amp. But this is fed at (near) line level. It is also regularly hot plugged when I'm using it to test things with a balanced output. Must have been done hundreds of times without problems. You still need those diodes even when there's no phantom power involved, because there is minimal static protection on the front end, and with repeated static zaps, eventually the small protection diodes on chip will fail. It's a cumulative effect over years, and the INA103 has similar issues. You might have damage from a ground loop and a nearby lightning strike inducing just a little too much voltage into an input that's already on the way out. If you send me the chip I can pop it open and tell you for sure how it failed. I'll be in London in a couple weeks as well. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#9
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SSM 2017
In article ,
Scott Dorsey wrote: Yes - I do that when using it as a mic pre-amp. But this is fed at (near) line level. It is also regularly hot plugged when I'm using it to test things with a balanced output. Must have been done hundreds of times without problems. You still need those diodes even when there's no phantom power involved, because there is minimal static protection on the front end, and with repeated static zaps, eventually the small protection diodes on chip will fail. Ah. Sadly, it's all now back together and working fine. And not the easiest of jobs to remove and strip down. It's a cumulative effect over years, and the INA103 has similar issues. You might have damage from a ground loop and a nearby lightning strike inducing just a little too much voltage into an input that's already on the way out. I've got plenty spares, so if it happens again I'll add the diodes. Have put a note on my schematic to that effect. If you send me the chip I can pop it open and tell you for sure how it failed. Sadly, went out in the rubbish, but thanks for the offer. I'll be in London in a couple weeks as well. Enjoy your stay. The weather is near perfect at the moment. Lets hope it continues. -- *A closed mouth gathers no feet.* Dave Plowman London SW To e-mail, change noise into sound. |
#11
Posted to rec.audio.pro
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SSM 2017
On 7/24/2014 9:49 AM, Scott Dorsey wrote:
You still need those diodes even when there's no phantom power involved, because there is minimal static protection on the front end, and with repeated static zaps, eventually the small protection diodes on chip will fail. It's a cumulative effect over years, and the INA103 has similar issues. You might have damage from a ground loop and a nearby lightning strike inducing just a little too much voltage into an input that's already on the way out. If you send me the chip I can pop it open and tell you for sure how it failed. I'll be in London in a couple weeks as well. There are plenty of SSM2017's on eBay, but a lot of them are from China. Are these real SSM2017's, or are they fakes? |
#12
Posted to rec.audio.pro
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SSM 2017
mcp6453 wrote:
On 7/24/2014 9:49 AM, Scott Dorsey wrote: You still need those diodes even when there's no phantom power involved, because there is minimal static protection on the front end, and with repeated static zaps, eventually the small protection diodes on chip will fail. It's a cumulative effect over years, and the INA103 has similar issues. You might have damage from a ground loop and a nearby lightning strike inducing just a little too much voltage into an input that's already on the way out. If you send me the chip I can pop it open and tell you for sure how it failed. I'll be in London in a couple weeks as well. There are plenty of SSM2017's on eBay, but a lot of them are from China. Are these real SSM2017's, or are they fakes? I cannot imagine people would be bothered to make fake SSM2017s, but these days you can never be sure. I mean, we are getting fake 2N3055s for God's sake. And fake CAT5! Buy from Mouser or Digi-Key, don't ever buy electronics parts from dodgy dealers on Ebay. And if you're replacing an SSM2017, try buying the pin-compatible replacement from THAT Semiconductor instead. It sounds better to my ears, and doesn't cost any more. Burr-Brown also has a replacement, the INA163, but I like the THAT one better. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#13
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SSM 2017
On Sat, 26 Jul 2014 21:38:23 -0400, mcp6453 wrote:
There are plenty of SSM2017's on eBay, but a lot of them are from China. Are these real SSM2017's, or are they fakes? I would assume they are counterfeit. It's the safest assumption, whether true or not. Even if they have authentic parts, have they stored them and will they ship them in proper ESD-safe packaging? If you send a message to the seller in China and ask them, can they even reply in sensible English? I suggest you replace the SSM2017 with another chip. Look into the TI INA217. Then you can purchase from a reputable distributor and know what you are getting. http://www.mouser.com/ds/2/405/sbos247b-125904.pdf |
#14
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SSM 2017
On Sat, 26 Jul 2014, Scott Dorsey wrote:
And if you're replacing an SSM2017, try buying the pin-compatible replacement from THAT Semiconductor instead. The chips are THAT 1510 and THAT 1512: http://www.thatcorp.com/datashts/THA..._Datasheet.pdf |
#15
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SSM 2017
On 27/07/2014 2:49 p.m., Scott Dorsey wrote:
I cannot imagine people would be bothered to make fake SSM2017s, but these days you can never be sure. They don't. They make fakes 1458/741s or whatever and stencil SSM2017 onto them. geoff |
#16
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SSM 2017
In article ,
mcp6453 wrote: There are plenty of SSM2017's on eBay, but a lot of them are from China. Are these real SSM2017's, or are they fakes? If you've read the entire thread, you'd know they date from the last century. -- *WHY IS THERE AN EXPIRATION DATE ON SOUR CREAM? Dave Plowman London SW To e-mail, change noise into sound. |