Hello all,
When dealing with older amplifiers, 20 y.o. plus, should you replace all of the electrolytic capacitors?
I am really talking about for personal use, one you just acquired and have no history on, but is working fine or one were possibly you find a bad cap or two.
If it was a customer's amplifier, is it prudent to suggest recapping?
When dealing with older amplifiers, 20 y.o. plus, should you replace all of the electrolytic capacitors?
I am really talking about for personal use, one you just acquired and have no history on, but is working fine or one were possibly you find a bad cap or two.
If it was a customer's amplifier, is it prudent to suggest recapping?
I think it's on a case by case situation.
I've seen plenty of caps still good after 20+ years and some in relatively new amps that failed.
In some amps (the older Orions, Some of the ZED, PG and Zapco amps), there were problems. Many times, it's just the primary filter caps.
When the caps leak and saturate the fiberglass board (more than leakage in the surface), the board may need to be cut away (as you saw in the tutorial).
In the older Orion amps, they often justify a complete recapping due to the fact that nearly all of the electrolytic caps fail.
I think it also depends on the owner. I've had some collectors that wanted the bare minimum done, leaving it as original as possible.
I think you need to be honest with the owner. Will the replacement of perfectly good caps make the amp perform better? Is it worth the cost? How do you know that the caps you're installing are better than the originals?
You need to think about all of the perfectly good caps that were replaced by the ones produced during the plague production years that are likely to cause damage where the originals would not have.
If you are trying to decide on replacement, I think you should pull some of each size/series and check them to see if they meet spec.
For parallel caps, if you find one of the parallel group defective, generally, all should be replaced. If, however, it's one of 20 or so expensive caps, you and the owner will have to discuss whether or not to do that. One failed in a group like that could have simply been one bad cap. Multiple failed will likely mean that they were damaged and should be replaced.
I've seen plenty of caps still good after 20+ years and some in relatively new amps that failed.
In some amps (the older Orions, Some of the ZED, PG and Zapco amps), there were problems. Many times, it's just the primary filter caps.
When the caps leak and saturate the fiberglass board (more than leakage in the surface), the board may need to be cut away (as you saw in the tutorial).
In the older Orion amps, they often justify a complete recapping due to the fact that nearly all of the electrolytic caps fail.
I think it also depends on the owner. I've had some collectors that wanted the bare minimum done, leaving it as original as possible.
I think you need to be honest with the owner. Will the replacement of perfectly good caps make the amp perform better? Is it worth the cost? How do you know that the caps you're installing are better than the originals?
You need to think about all of the perfectly good caps that were replaced by the ones produced during the plague production years that are likely to cause damage where the originals would not have.
If you are trying to decide on replacement, I think you should pull some of each size/series and check them to see if they meet spec.
For parallel caps, if you find one of the parallel group defective, generally, all should be replaced. If, however, it's one of 20 or so expensive caps, you and the owner will have to discuss whether or not to do that. One failed in a group like that could have simply been one bad cap. Multiple failed will likely mean that they were damaged and should be replaced.
Perry,
Thanks for the detailed response.
I've got a punch 40i dsm that I know has a bad cap, it has eaten into the main pcb, so that is one reason I was asking.
Also I have seen people selling older amplifiers, claiming they have been "completely re-capped" and seen forum posts where someone will say "the first thing I do when I get an old amplifier is re-cap it" and I wonder is that really warranted. I am more of the thought that if it is not broken don't fixit, but I didn't know. You make a very good point, that there is no guarantee that the new one is any better than the original and very well may fail before the original would have.
My downfall getting back into car audio later in life is that I see these amplifiers from a perspective of a 16 year old from the 80's when some of these amps cost several times what my vehicle did back then. Needless to say, I could not afford them then. An 8-track and a couple of used Kraco 6x9s were a stretch. Any way what I am getting at is in reality these are $150.00 or less amps that may cost $50.00 or more to re-cap and you still have a $150.00 amp.
Probably best to enjoy it until it quits, then fix what's broken.
Thanks for the detailed response.
I've got a punch 40i dsm that I know has a bad cap, it has eaten into the main pcb, so that is one reason I was asking.
Also I have seen people selling older amplifiers, claiming they have been "completely re-capped" and seen forum posts where someone will say "the first thing I do when I get an old amplifier is re-cap it" and I wonder is that really warranted. I am more of the thought that if it is not broken don't fixit, but I didn't know. You make a very good point, that there is no guarantee that the new one is any better than the original and very well may fail before the original would have.
My downfall getting back into car audio later in life is that I see these amplifiers from a perspective of a 16 year old from the 80's when some of these amps cost several times what my vehicle did back then. Needless to say, I could not afford them then. An 8-track and a couple of used Kraco 6x9s were a stretch. Any way what I am getting at is in reality these are $150.00 or less amps that may cost $50.00 or more to re-cap and you still have a $150.00 amp.
Probably best to enjoy it until it quits, then fix what's broken.