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#1
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Spin from Bipolar caps
Wayne wrote:
This may be a little OT, but it still has to do with caps. I've got a Fender '65 Twin thats got old GE paper electrolytics in the B+ circuit. Most are 20uf @ 450 volts. I'm a relunctant to replace those with NOS for the obvious reasons the NOS probably are not gonna be an improvement over whats in there now. NOS caps will probably be worse, since they will have been sitting on the shelf for a long time. First. Is it advisable to replace with something else, since technology changes and this is 40 year old design.? If you change them with a modern technology cap, the amp will sound different. This could be good or bad. If you replace them with a new cap of old design (Antique Electronics Supply has a nice selection), it will sound much the same. Second, I'm having problems finding new replacements because of the 450v requirement. Panasonic makes some modern ones. Mallory I think makes some old ones. Are these metal can types? Personally I would go to a 600V one for somewhat longer life. Third, should I also replace all those .1mfd and .047mfd while I'm at it and with what? If they are paper caps, putting anything else in there will change the sound but improve reliability. BTW, I'm really not interested in changing the "sound" of the Twin. It's a great amp as is!!! Just wanting to clean up some of the hum, etc. Anything you do will change the sound, which is the problem. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#2
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Wayne wrote:
This may be a little OT, but it still has to do with caps. I've got a Fender '65 Twin thats got old GE paper electrolytics in the B+ circuit. Most are 20uf @ 450 volts. I'm a relunctant to replace those with NOS for the obvious reasons the NOS probably are not gonna be an improvement over whats in there now. NOS caps will probably be worse, since they will have been sitting on the shelf for a long time. First. Is it advisable to replace with something else, since technology changes and this is 40 year old design.? If you change them with a modern technology cap, the amp will sound different. This could be good or bad. If you replace them with a new cap of old design (Antique Electronics Supply has a nice selection), it will sound much the same. Second, I'm having problems finding new replacements because of the 450v requirement. Panasonic makes some modern ones. Mallory I think makes some old ones. Are these metal can types? Personally I would go to a 600V one for somewhat longer life. Third, should I also replace all those .1mfd and .047mfd while I'm at it and with what? If they are paper caps, putting anything else in there will change the sound but improve reliability. BTW, I'm really not interested in changing the "sound" of the Twin. It's a great amp as is!!! Just wanting to clean up some of the hum, etc. Anything you do will change the sound, which is the problem. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#3
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Wayne wrote:
I've got a Fender '65 Twin thats got old GE paper electrolytics in the B+ circuit. Most are 20uf @ 450 volts. I'm a relunctant to replace those with NOS for the obvious reasons the NOS probably are not gonna be an improvement over whats in there now. Brand new ones will be fine. www.tubesandmore.com Yours should have had 525-volt, since there's more than 450 volts on them. First. Is it advisable to replace with something else, since technology changes and this is 40 year old design.? Sure. Second, I'm having problems finding new replacements because of the 450v requirement. 450's are stocked about everywhere, like www.mouser.com. But you should use a higher rating. Third, should I also replace all those .1mfd and .047mfd while I'm at it and with what? Not if they're not causing a problem. BTW, I'm really not interested in changing the "sound" of the Twin. It's a great amp as is!!! Just wanting to clean up some of the hum, etc. Therefore you *should* replace the power supply filters; do the 50 that's in the bias supply too. I can solder and do the light stuff, but I'm not an schooled in electronics. Since lethal voltages are present, don't even start this yourself. Take it in to someone who won't get killed. |
#4
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Wayne wrote:
I've got a Fender '65 Twin thats got old GE paper electrolytics in the B+ circuit. Most are 20uf @ 450 volts. I'm a relunctant to replace those with NOS for the obvious reasons the NOS probably are not gonna be an improvement over whats in there now. Brand new ones will be fine. www.tubesandmore.com Yours should have had 525-volt, since there's more than 450 volts on them. First. Is it advisable to replace with something else, since technology changes and this is 40 year old design.? Sure. Second, I'm having problems finding new replacements because of the 450v requirement. 450's are stocked about everywhere, like www.mouser.com. But you should use a higher rating. Third, should I also replace all those .1mfd and .047mfd while I'm at it and with what? Not if they're not causing a problem. BTW, I'm really not interested in changing the "sound" of the Twin. It's a great amp as is!!! Just wanting to clean up some of the hum, etc. Therefore you *should* replace the power supply filters; do the 50 that's in the bias supply too. I can solder and do the light stuff, but I'm not an schooled in electronics. Since lethal voltages are present, don't even start this yourself. Take it in to someone who won't get killed. |
#5
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"Wayne" wrote in message ... This may be a little OT, but it still has to do with caps. I've got a Fender '65 Twin thats got old GE paper electrolytics in the B+ circuit. Most are 20uf @ 450 volts. I'm a relunctant to replace those with NOS for the obvious reasons the NOS probably are not gonna be an improvement over whats in there now. Correct. They're likely to be just as bad, maybe worse. First. Is it advisable to replace with something else, since technology changes and this is 40 year old design.? Second, I'm having problems finding new replacements because of the 450v requirement. Third, should I also replace all those .1mfd and .047mfd while I'm at it and with what? BTW, I'm really not interested in changing the "sound" of the Twin. It's a great amp as is!!! Just wanting to clean up some of the hum, etc. The problem is, you *are* going to change the sound. Why? Because as the capacitors have aged, you've gotten used to the sound of an amp with bad, saggy, worn out supply caps. When you replace them with caps that actually do what they're supposed to, you'll hear a different sound, probably pretty close to what the amp sounded like when it was new (discounting the changes in the speakers, of course). So you're going to change it; sorry, that's just the way life is sometimes. You can get new caps various places; Panasonic makes a 33uF 450V one (TSUP series), and they have some other TSxx 450V series with higher temperature ratings, which will improve reliability, but they're all bigger than 33uF. I would like that (nice tight bass) but it'll further change the sound, and you might not like it. Panasonic caps are available at Digi-Key (www.digikey.com). Or you can get something a lot closer to what Fender used from Antique Electronic Supply (www.tubesandmore.com). I'd stay away from the NOS stuff, though; as you noted, it probably won't clean your hum up. Peace, Paul |
#6
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"Wayne" wrote in message ... This may be a little OT, but it still has to do with caps. I've got a Fender '65 Twin thats got old GE paper electrolytics in the B+ circuit. Most are 20uf @ 450 volts. I'm a relunctant to replace those with NOS for the obvious reasons the NOS probably are not gonna be an improvement over whats in there now. Correct. They're likely to be just as bad, maybe worse. First. Is it advisable to replace with something else, since technology changes and this is 40 year old design.? Second, I'm having problems finding new replacements because of the 450v requirement. Third, should I also replace all those .1mfd and .047mfd while I'm at it and with what? BTW, I'm really not interested in changing the "sound" of the Twin. It's a great amp as is!!! Just wanting to clean up some of the hum, etc. The problem is, you *are* going to change the sound. Why? Because as the capacitors have aged, you've gotten used to the sound of an amp with bad, saggy, worn out supply caps. When you replace them with caps that actually do what they're supposed to, you'll hear a different sound, probably pretty close to what the amp sounded like when it was new (discounting the changes in the speakers, of course). So you're going to change it; sorry, that's just the way life is sometimes. You can get new caps various places; Panasonic makes a 33uF 450V one (TSUP series), and they have some other TSxx 450V series with higher temperature ratings, which will improve reliability, but they're all bigger than 33uF. I would like that (nice tight bass) but it'll further change the sound, and you might not like it. Panasonic caps are available at Digi-Key (www.digikey.com). Or you can get something a lot closer to what Fender used from Antique Electronic Supply (www.tubesandmore.com). I'd stay away from the NOS stuff, though; as you noted, it probably won't clean your hum up. Peace, Paul |
#7
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Brand new ones will be fine. www.tubesandmore.com
Yours should have had 525-volt, since there's more than 450 volts on them. You're right. It's the AB763 schematic which specifies 525. Most of the working voltages are around 450. There's also some 25/25 in there. I'll probably just change the 20/525's, the 50/50 in the bias circuit and the 25/25's. Thanks for the hi-voltage warning, but I'm already familiar with that. I usually just unplug from the wall and do the screwdriver to chassis welding function. I used to work on microwave ovens and those trash cans can flat ruin your day alright. Thanks for the help --Wayne -"sounded good to me"- |
#8
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Brand new ones will be fine. www.tubesandmore.com
Yours should have had 525-volt, since there's more than 450 volts on them. You're right. It's the AB763 schematic which specifies 525. Most of the working voltages are around 450. There's also some 25/25 in there. I'll probably just change the 20/525's, the 50/50 in the bias circuit and the 25/25's. Thanks for the hi-voltage warning, but I'm already familiar with that. I usually just unplug from the wall and do the screwdriver to chassis welding function. I used to work on microwave ovens and those trash cans can flat ruin your day alright. Thanks for the help --Wayne -"sounded good to me"- |
#9
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"Wayne" wrote in message
Brand new ones will be fine. www.tubesandmore.com Yours should have had 525-volt, since there's more than 450 volts on them. You're right. It's the AB763 schematic which specifies 525. Most of the working voltages are around 450. There's also some 25/25 in there. I'll probably just change the 20/525's, the 50/50 in the bias circuit and the 25/25's. Thanks for the hi-voltage warning, but I'm already familiar with that. I usually just unplug from the wall and do the screwdriver to chassis welding function. I used to work on microwave ovens and those trash cans can flat ruin your day alright. That's why God invented 100 ohm 5 watt resistors - they take the sting out of the *welding function*. |
#10
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"Wayne" wrote in message
Brand new ones will be fine. www.tubesandmore.com Yours should have had 525-volt, since there's more than 450 volts on them. You're right. It's the AB763 schematic which specifies 525. Most of the working voltages are around 450. There's also some 25/25 in there. I'll probably just change the 20/525's, the 50/50 in the bias circuit and the 25/25's. Thanks for the hi-voltage warning, but I'm already familiar with that. I usually just unplug from the wall and do the screwdriver to chassis welding function. I used to work on microwave ovens and those trash cans can flat ruin your day alright. That's why God invented 100 ohm 5 watt resistors - they take the sting out of the *welding function*. |
#11
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"Paul Stamler" wrote in message news:Eu1sd.86067 The problem is, you *are* going to change the sound. Why? Because as the capacitors have aged, you've gotten used to the sound of an amp with bad, saggy, worn out supply caps. When you replace them with caps that actually do what they're supposed to, you'll hear a different sound, probably pretty close to what the amp sounded like when it was new (discounting the changes in the speakers, of course). A bit like changing your guitar strings really ! geoff |
#12
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"Paul Stamler" wrote in message news:Eu1sd.86067 The problem is, you *are* going to change the sound. Why? Because as the capacitors have aged, you've gotten used to the sound of an amp with bad, saggy, worn out supply caps. When you replace them with caps that actually do what they're supposed to, you'll hear a different sound, probably pretty close to what the amp sounded like when it was new (discounting the changes in the speakers, of course). A bit like changing your guitar strings really ! geoff |
#13
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Arny Krueger wrote:
"Wayne" wrote in message Thanks for the hi-voltage warning, but I'm already familiar with that. I usually just unplug from the wall and do the screwdriver to chassis welding function. I used to work on microwave ovens and those trash cans can flat ruin your day alright. That's why God invented 100 ohm 5 watt resistors - they take the sting out of the *welding function*. Well, Leo already gave you some, just turn the Standby switch on after you've turned the power off, there are bleeder resistors on the two 70-uF filter input caps. |
#14
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Arny Krueger wrote:
"Wayne" wrote in message Thanks for the hi-voltage warning, but I'm already familiar with that. I usually just unplug from the wall and do the screwdriver to chassis welding function. I used to work on microwave ovens and those trash cans can flat ruin your day alright. That's why God invented 100 ohm 5 watt resistors - they take the sting out of the *welding function*. Well, Leo already gave you some, just turn the Standby switch on after you've turned the power off, there are bleeder resistors on the two 70-uF filter input caps. |
#15
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If the caps are old they my no longer be 20 uf @ 450 volts should not be
that hard to find. Be wary of tantalum caps since the failure mode is to chatch on fire. Go for the aluminum electrolytics, they just explode or go open. Bob "Wayne" wrote in message ... This may be a little OT, but it still has to do with caps. I've got a Fender '65 Twin thats got old GE paper electrolytics in the B+ circuit. Most are 20uf @ 450 volts. I'm a relunctant to replace those with NOS for the obvious reasons the NOS probably are not gonna be an improvement over whats in there now. First. Is it advisable to replace with something else, since technology changes and this is 40 year old design.? Second, I'm having problems finding new replacements because of the 450v requirement. Third, should I also replace all those .1mfd and .047mfd while I'm at it and with what? BTW, I'm really not interested in changing the "sound" of the Twin. It's a great amp as is!!! Just wanting to clean up some of the hum, etc. I can solder and do the light stuff, but I'm not an schooled in electronics. Thanks, --Wayne -"sounded good to me"- |
#16
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If the caps are old they my no longer be 20 uf @ 450 volts should not be
that hard to find. Be wary of tantalum caps since the failure mode is to chatch on fire. Go for the aluminum electrolytics, they just explode or go open. Bob "Wayne" wrote in message ... This may be a little OT, but it still has to do with caps. I've got a Fender '65 Twin thats got old GE paper electrolytics in the B+ circuit. Most are 20uf @ 450 volts. I'm a relunctant to replace those with NOS for the obvious reasons the NOS probably are not gonna be an improvement over whats in there now. First. Is it advisable to replace with something else, since technology changes and this is 40 year old design.? Second, I'm having problems finding new replacements because of the 450v requirement. Third, should I also replace all those .1mfd and .047mfd while I'm at it and with what? BTW, I'm really not interested in changing the "sound" of the Twin. It's a great amp as is!!! Just wanting to clean up some of the hum, etc. I can solder and do the light stuff, but I'm not an schooled in electronics. Thanks, --Wayne -"sounded good to me"- |
#17
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"Wayne" This may be a little OT, but it still has to do with caps. I've got a Fender '65 Twin thats got old GE paper electrolytics in the B+ circuit. Most are 20uf @ 450 volts. I'm a relunctant to replace those with NOS for the obvious reasons the NOS probably are not gonna be an improvement over whats in there now. BTW, I'm really not interested in changing the "sound" of the Twin. It's a great amp as is!!! Just wanting to clean up some of the hum, etc. ** Your hum may easily be due to the pre-amp tubes or defective grounding of the heater supply. Take it to an amp tech and don't make it a nightmare out of it for him by messing with it first. ............ Phil |
#18
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"Wayne" This may be a little OT, but it still has to do with caps. I've got a Fender '65 Twin thats got old GE paper electrolytics in the B+ circuit. Most are 20uf @ 450 volts. I'm a relunctant to replace those with NOS for the obvious reasons the NOS probably are not gonna be an improvement over whats in there now. BTW, I'm really not interested in changing the "sound" of the Twin. It's a great amp as is!!! Just wanting to clean up some of the hum, etc. ** Your hum may easily be due to the pre-amp tubes or defective grounding of the heater supply. Take it to an amp tech and don't make it a nightmare out of it for him by messing with it first. ............ Phil |
#19
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Scott Dorsey wrote:
Wayne wrote: This may be a little OT, but it still has to do with caps. I've got a Fender '65 Twin thats got old GE paper electrolytics in the B+ circuit. Most are 20uf @ 450 volts. I'm a relunctant to replace those with NOS for the obvious reasons the NOS probably are not gonna be an improvement over whats in there now. NOS caps will probably be worse, since they will have been sitting on the shelf for a long time. First. Is it advisable to replace with something else, since technology changes and this is 40 year old design.? If you change them with a modern technology cap, the amp will sound different. This could be good or bad. If you replace them with a new cap of old design (Antique Electronics Supply has a nice selection), it will sound much the same. Second, I'm having problems finding new replacements because of the 450v requirement. Panasonic makes some modern ones. Mallory I think makes some old ones. Are these metal can types? Personally I would go to a 600V one for somewhat longer life. Third, should I also replace all those .1mfd and .047mfd while I'm at it and with what? If they are paper caps, putting anything else in there will change the sound but improve reliability. BTW, I'm really not interested in changing the "sound" of the Twin. It's a great amp as is!!! Just wanting to clean up some of the hum, etc. Anything you do will change the sound, which is the problem. OTOH you may be well pleased with the changed sound ! I had a few original Vox AC30s in for repairs many years ( decades ) back. Most of the problems were 'burnt out' 100k anode / plate resistors and horrible 'Hunts' 0.01uF coupling caps that degrade with time to the extent that the plastic case would literally 'crumble' like dry bread ! Relaced those parts with new stock of modern characteristics - e.g. metal oxide / film Rs and plastic film caps. Also found a poor output stage biasing problem ( used cathode bias alone ) that meant that the 2 paralled EL84s on each side of the push-pull arrangement ( 4 x EL84s total ) shared -ve bias and therefore there was no way of assuring any remote chance of matching Ia. Changed this to a proper individual bias arrangement. The owners were well pleased with the results. It was like giving the amps a new lease of life and a breath of fresh air. Graham |
#20
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Scott Dorsey wrote:
Wayne wrote: This may be a little OT, but it still has to do with caps. I've got a Fender '65 Twin thats got old GE paper electrolytics in the B+ circuit. Most are 20uf @ 450 volts. I'm a relunctant to replace those with NOS for the obvious reasons the NOS probably are not gonna be an improvement over whats in there now. NOS caps will probably be worse, since they will have been sitting on the shelf for a long time. First. Is it advisable to replace with something else, since technology changes and this is 40 year old design.? If you change them with a modern technology cap, the amp will sound different. This could be good or bad. If you replace them with a new cap of old design (Antique Electronics Supply has a nice selection), it will sound much the same. Second, I'm having problems finding new replacements because of the 450v requirement. Panasonic makes some modern ones. Mallory I think makes some old ones. Are these metal can types? Personally I would go to a 600V one for somewhat longer life. Third, should I also replace all those .1mfd and .047mfd while I'm at it and with what? If they are paper caps, putting anything else in there will change the sound but improve reliability. BTW, I'm really not interested in changing the "sound" of the Twin. It's a great amp as is!!! Just wanting to clean up some of the hum, etc. Anything you do will change the sound, which is the problem. OTOH you may be well pleased with the changed sound ! I had a few original Vox AC30s in for repairs many years ( decades ) back. Most of the problems were 'burnt out' 100k anode / plate resistors and horrible 'Hunts' 0.01uF coupling caps that degrade with time to the extent that the plastic case would literally 'crumble' like dry bread ! Relaced those parts with new stock of modern characteristics - e.g. metal oxide / film Rs and plastic film caps. Also found a poor output stage biasing problem ( used cathode bias alone ) that meant that the 2 paralled EL84s on each side of the push-pull arrangement ( 4 x EL84s total ) shared -ve bias and therefore there was no way of assuring any remote chance of matching Ia. Changed this to a proper individual bias arrangement. The owners were well pleased with the results. It was like giving the amps a new lease of life and a breath of fresh air. Graham |
#21
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Phil Allison wrote:
"Wayne" This may be a little OT, but it still has to do with caps. I've got a Fender '65 Twin thats got old GE paper electrolytics in the B+ circuit. Most are 20uf @ 450 volts. I'm a relunctant to replace those with NOS for the obvious reasons the NOS probably are not gonna be an improvement over whats in there now. BTW, I'm really not interested in changing the "sound" of the Twin. It's a great amp as is!!! Just wanting to clean up some of the hum, etc. ** Your hum may easily be due to the pre-amp tubes or defective grounding of the heater supply. Take it to an amp tech and don't make it a nightmare out of it for him by messing with it first. Amen to " don't make it a nightmare out of it for him by messing with it first " ! If only ppl would respect their limitations. Seen some weird **** done to gear. Graham |
#22
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Phil Allison wrote:
"Wayne" This may be a little OT, but it still has to do with caps. I've got a Fender '65 Twin thats got old GE paper electrolytics in the B+ circuit. Most are 20uf @ 450 volts. I'm a relunctant to replace those with NOS for the obvious reasons the NOS probably are not gonna be an improvement over whats in there now. BTW, I'm really not interested in changing the "sound" of the Twin. It's a great amp as is!!! Just wanting to clean up some of the hum, etc. ** Your hum may easily be due to the pre-amp tubes or defective grounding of the heater supply. Take it to an amp tech and don't make it a nightmare out of it for him by messing with it first. Amen to " don't make it a nightmare out of it for him by messing with it first " ! If only ppl would respect their limitations. Seen some weird **** done to gear. Graham |
#23
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Go for the aluminum electrolytics, they just explode or go
open. Bob I ordered all Sprague Atom caps from Triode Electronics. Had to go with the 500v instead of 600v cause they don't fit under the shield. Thanks to all for your help. --Wayne -"sounded good to me"- |
#24
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Go for the aluminum electrolytics, they just explode or go
open. Bob I ordered all Sprague Atom caps from Triode Electronics. Had to go with the 500v instead of 600v cause they don't fit under the shield. Thanks to all for your help. --Wayne -"sounded good to me"- |
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