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Why re-cap? Once and For All.

depends on the age and usage. recent vintage, hot power supply, just do the PS caps
older, with noises, and occasional random hiss/noise, then PS and that channel
over 20 years - all of them, everyone, all the black/red/gold/green/blue ones

like cars
3 years old, 60K miles, thread down below 1/32 - replace tires
20 years old, replace all belts, tires, anything rubber, synthetic, alien, psychotic
1987 Corvette, replace anything and everything, torque heads, screws, bolts, nuts

or do it over time, one component at a time, pay labor rates for dis-assembly
each and every time, note the missing screws from repeated repairs,
note the scuff mark on the top edge on the 6th repair, after the 9th repair
replaced parts, documentation no longer given, and owner has announced
alien abduction of self with no forwarding address.

or (heaven forbid) dump it on the road on the way to work or on that
next visit to the city/county dump. raising the height of the landfill one
unit at a time.
 
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ConradH said:
So, at what year should a total recap be done?

"Once and for all", not too sure it will stick! :)
Click to expand...

It won't.

You can lead a horse to water....
I worked at the EPA as a college student, they have a saying, "You can protect the fools, but you cannot protect the damn fools".


It took me a while to "believe", but years of fixing showed a lot of problems caused by bad caps.
The ones in the photos were "hiding" in a working unit. The only way to find them was wholesale replacement, or some serious talent with circuit analysis and testing. Someone had put a hack on to get it working, but it was a bandaid on a broken arm.

Years of fixing also taught me that caps that looked good and tested good on cheap testers, were still not good.

I don't mean to sell a re-cap as a general improvement practice. I've had a few units that didn't get massively better with fresh caps. I run many units as is that sound great. But, I have seen many many units that had small issues (random poor reception, imbalanced channels, random static) or just lame sound that improved so much that it was more like a repair. And, I guess it really was a repair where the only way to repair it ended up being a re-cap.

My real point is, there is no reason not to do it and many reasons to do it.

Doing a partial job may or may not be wise.
As Yoda said, "Do or do not, there is no try".
Well, OK, there is "try" here but be ready for no audible change, or to do more, and still no audible change. You can't make a race car out of a dump truck.
The small signal caps cause much more problems than the larger power line caps.

I do want to point out that a re-cap may not buy another 30-40 years.
Other parts are 30-40-50 years old and can fail too.
But, the e-caps are the weakest link in general.

If your unit works well and sounds great, fine, enjoy.
If you have a unit that is supposed to be a great unit but doesn't measure up, the e-caps may be why.
If you get a re-cap done and still don't like it, it may be the voicing of the make and model, your ears or music or speakers or there are more issues with that unit. Lemons exist.

I will also point out that while doing a re-cap, years of experience taught me other things to watch for.
Blob diodes, 2SC458s, fusistors, bad solder joints, bad repairs, broken wires, dirty controls, factory screw ups, failing switches, etc... All things that add up to the art and skill of restoration.
 
Oerets said:
When replacing a bad cap in a crossover does one just replace only the bad?

Or just do them all?
Click to expand...

I'd do them all if for no better reason than I don't want to mess with it again. I hate "frequent fliers" on the bench, so I usually try to fix things in a manner that keeps them in service as long as practical. I do that with my cars too. I've been accused of being a parts replacer but they all run reliably and in the long run I spend less money on stuff.
 
As most people will do, the first thing I do when I first get a stereo on my bench is to put a signal to it and look at it on the scope on the pre amp side and the main output. When using a square wave many times it is not so square, round corners and not flat on the top. Changing the caps has always cleaned up the square wave.

I watch a youtube video where this guy pulled two 1 uF 16 V caps out of a old stereo and measure them. Both were at 1uF, one with a high esr and the other had a good esr. He then tested them on a Heath kit cap tester. The one with the good esr failed before it reach rated voltage. I am not going to go through all of this testing for a part that is very cheap.

I do test many of the caps that I pull when doing a recap. Sometimes none of them tested bad, other times there are some bad ones. But my LCR meter uses a 9 volt battery and has it limits.
 
The argument for a recap gets stronger every year! This stuff ain't getting any younger. Still, I don't believe in fixed rules and I do what the situation indicates. Usually I do more than what's indicated because I can't leave well enough alone. As long as the board is out...

Just don't forget the rest of the parts. Some people want to blame electrolytics for everything, but I've seen some weird leakage issues with ceramics and certainly tantalums that otherwise would have tested good. Enough to affect sound or FM performance or whatever, depending on where they were in the circuit. It isn't usually wise or sensible to pull ceramics, so you have to troubleshoot with good test equipment and (hopefully) a good brain. Don't forget the damn corrosive glue. Don't forget the known troublemakers (not AKers, but stuff like 458s). Don't forget the switches and pots. .Don't forget cleaning and lubing the mechanics like tuner mechanisms. Don't forget to clean the obscure switches that never get switched, like bridging and local/dx. Don't forget the 1/4" bump test- if you bump it and get noise, the job probably isn't done. Maybe it's luck, good or bad, I've seen fewer problems caused by caps than anything else, unless you start counting rather elderly equipment. Then they're probably all bad.
 
ConradH said:
So, at what year should a total recap be done?

"Once and for all", not too sure it will stick! :)
Click to expand...

Conrad is the 'master' of the 'capacitor abyss'. He's not only tested ss component models but bags of caps and a variety of caps as well.

I have an sta-2300 with low hours and after resolder job I noticed poor factory solder during internal cleaning, the unit on my custom est. 92+db speakers still sounds great even 'better half' after assembly said "you should keep that" (was considering selling it) and her ears are just as good as her sense of smell. :D
 
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blhagstrom said:
Won’t modify, the circuit can’t take advantage of the trick wazoo caps.
Click to expand...

Given the poor results, I wouldn't necessarily use the word 'advantage'! :)

Something has caused the sound quality to go backwards. All things being equal (and no other faults or issues being introduced during the recapping process - at least you can't get the polarity of film caps wrong!), I'm looking fairly and squarely at the replacement boutique caps.
 
Oerets said:
I just had a tube amplifier go south that had replacement cans installed in 2003. One started leaking. Still was functioning just leaking oil.
Barney
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One of the distributors had a bunch that were failing in that time period. They've since corrected it.
 
bimasta said:
The argument may be right. But it's weakened by choosing as the main example a Marantz that had been butchered by a previous owner.

A better example would a component in immaculate, original condition, seeming to work properly, and why it still needs a full recap. That would be very persuasive. The existing example is not. It's not yet "the 'link to' once and for all" that you intend.

I have several very good components in original condition and working beautifully. I know the caps are near or past their expiry date and I want to be persuaded.
Click to expand...


I too have been a want-to-believe guy. I had a chance to listen to my stock, aged, Pioneer SX-1250 next to one that came to me strictly for a controls cleaning but had been re-capped. My sound system, my room, my knowledge of how the music sounds through my Pioneer. The recapped unit was cleaner, tighter and with a much improved sound stage. The bass recessed a bit from the non-recapped but overall I'd call it an marked improvement. Worth the cost? That I don't know.
 
VTDave, interesting you mentioned that you felt the bass recess, I've recapped a couple of receivers and it wasn't until the tone board was changed that the sound became cleaner and tighter, I too noticed the bass retract from those that have not yet had the tone board recapped. Going to do another one soon without the use of films to see if there is a significant change.
 
VTDave said:
I too have been a want-to-believe guy. I had a chance to listen to my stock, aged, Pioneer SX-1250 next to one that came to me strictly for a controls cleaning but had been re-capped. The recapped unit was cleaner, tighter and with a much improved sound stage. Worth the cost? That I don't know.
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Thanks Dave. i shortened your comment to the gist, hope you don't mind. You had 2 identical amps, one stock, one recapped, and compared. Moreover, you're experienced in doing such work yourself. So it's informed advice. Thanks.
 
ConradH said:
I absolutely positively don't believe in break-in after a recap, but I still hear it and the sound improves. Maybe I'm just some joker on the internet after all.
Click to expand...
Even comments on AK need break in.....although the wording visibly stays the same...:)

I would suggest because a lot of electrolytic caps hardly get enough DC voltage to do a good reforming process when mounted, sometimes reform processes may take longer time or do not happen at all.
Maybe I am nitpicking but when a new electrolytic gets into a position where there is no DC voltage or less than one volt, I like to put voltage on it and bleed it again making sure it is healthy before it gets in, Just for peace of mind.
 
I did form up the HV caps I put in my Phase Linear. I let them cook at rated voltage overnight through a limiting resistor. The leakage dropped considerably during that time. Didn't bother with the Sherwood or the Allied. Mostly didn't think of it, but partly was just anxious to get the thing done so I could move on to another project.
 
i never noticed any difference in sound on my recaps that would be from break in but i wasnt really listening for it. i do like to let my gear warm up for a half hour though mostly because when ive adjusted idle current it seems to fluctuate a bit until the receivers been on for a while
 
FWIW, I do a leakage test on every cap I use, to full rated voltage, so they're fully formed. I doesn't exist, but I still hear it.
 
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