Why re-cap? Once and For All.

[gadget73]

ive had 15 ( 40-55 year old) recaps, only 2 were done in hopes of improving the sound

Thats fine. I was specifically meaning situations where the unit has some obvious malfunction and the standard solution is "put new caps in it" without being sure that was the problem. I certainly won't discourage people from recapping things, even if its not needed. I don't even think its necessarily a bad idea. I just hate to see people go to a lot of effort and expense in replacing a load of parts that have nothing to do with the problem. From experience I know its very frustrating to put a lot of work and money into something and its still broken.

 

[KingBubba]

The adage is fix the problem first, then do the maintenance. I ask to have my equipment recapped because I can't do it myself and I can't afford to send it out everytime a cap goes South. A bad cap can bring out other problems, which I just don't want or need. Modular equipment like an SX - 1250 is something I probably could deal with, but more equipment is like a Sansui Model Eight or an Onkyo TX 4500 or 4500MkII, which are hell to work on. I don't ever bother with a tuner because Central Florida has no stations worth listening to.

 

[pete_mac]

Umm... maybe not yet...

I 'd love to recap the great vintage amps I love, just to extend their lives. I can do the work, just need a couple new tools, so it would only the cost of the caps. But I read/hear so many tales of recaps gone bad. Chrisxo's comments are very reassuring — 15 full recaps without one dud: that's a big sample size.

But a friend of mine recapped his power amp. Don't ask me for details because I don't have them (a) it was years ago (b) he was only a casual acquaintance (c) I wasn't involved (d) I'm not even sure what amp it was — a think a fairly rare Marantz Esotec SM-1000 he always bragged about, thought was heaven on earth, and it deserved the best.

He replaced every cap with a Hovland cap, each one handmade to the highest standard with the finest materials — and when Hovland didn't have the right value he used them in parallel or series to stay within very close tolerance. Hovland caps were very expensive — each one could feed a family of four for a week (not the caps, the money).

When he was done, he told me the amp sounded TERRIBLE! He'd ruined his beloved amp! He ran out of adjectives to describe how bad it was, even after twenty adjectives we're not allowed to use here on AK.

He took out all the Hovlands and put the old ones back in. He was back in heaven — but staring at a pile of Hovlands, which cost him a small fortune, and were now "used", with a resale value of ?????

That's only one anecdote of one recap failure. Chrisxo offers 15 anecdotes of 15 recap successes.

But it does demonstrate, pretty dramatically, that a recap can go wrong. That might happen to mine. I'm sure you can all understand why I'm a little bit uncertain...

That's an interesting example, and is not necessarily consistent with your average recap. The wholesale replacement of all electrolytics with boutique film caps treads a fine line between 'recap' and 'modification' IMHO.

 

[UncleBingo]

I've done recaps/restorations for people that were moving to places where there was little/no apparent access to reputable vintage audio repair.That is reason enough, imo.

Having done many, there are components I trust less than caps, but as a frequency-shaping component in audio circuits, I want caps closer to spec than not.

 

[s-petersen]

Best movie line? Time is the fire in which we burn.

Blade Runner?
The only recap that was bad that I have seen, was when someone replaced a 390pf cap with a .1 by mistake, it killed the HF frequencies

 

[Sharpstik]

Having done many, there are components I trust less than caps,

Could you name some ?
I will check my restoration data sheets to see if the components you name are on there.

 

[dbxdx5]

That's an interesting example, and is not necessarily consistent with your average recap. The wholesale replacement of all electrolytics with boutique film caps treads a fine line between 'recap' and 'modification' IMHO.

I have to agree here.

 

[blhagstrom]

Blade Runner?
The only recap that was bad that I have seen, was when someone replaced a 390pf cap with a .1 by mistake, it killed the HF frequencies

Star Trek, Generations.

That's an interesting example, and is not necessarily consistent with your average recap. The wholesale replacement of all electrolytics with boutique film caps treads a fine line between 'recap' and 'modification' IMHO.

Won’t modify, the circuit can’t take advantage of the trick wazoo caps.

Race tires on a horse buggy.

 

[blhagstrom]

Could you name some ?
I will check my restoration data sheets to see if the components you name are on there.

VD-1212 diodes.
MV-13 diodes.
2SC-458 outhouse transistors.
Fusistors, I’ve only seen a few that were even near right.
Tantalum caps.

All those are on my hit list.

Just fixed a Mitsubishi DA-15DC with bad MV-13 and a recap.

I’ve seen enough diff pairs so out of whack that I’m tempted to just replace them on a rebuild too.

 

[Bob]

there are many recap reasons

1, you hear crap and you know its a cap. there are 8. pulling one leg and testing each didn't find
the problem - cap value and ESR are within acceptable margins. easier to do all 8 rather than
trying to find 1 and repeating it another 7 times to really destroy the through holes, traces, and maybe
the board.
2. allows you to see if there are any WTFs like polarized caps wired in backwards, cap value different
than parts layout, schematic, or parts list, or even the exact same cap on the other channel
3. lets you see if there have been any fixes that you can undo, fix, remove, revert, etc. there
may have been wholesale crap caps to begin with, or mostly done as an attempt to boutique it.
4. the unit is now 40YO and you know it will not last another 40 and its in a rack with about
20 cables in/out/sideways and you have only enough energy to do this once. recap all is a
categorical imperative. repeat for all the other 40YO things in your rack.
5. the sound changes and you want the original sound back.

now - why recaps sometimes sound like crap
1. needs burn-in - witness the thousands of threads on the now unobtanium black gates that
needed dozens of hours to burn-in and about 2 hours to sound good each time you powered on
2. your unit deteriorated to the point that it sounded like crap but you got used to the deterioration
over the last 40 years and that unit needed a recap 20 years ago. after recap it sure sounds
different. some say better and others say crap
3. you are a cap-denier and cannot tell the truth about recapping and will always say the sound
is crap because if you say the sound is good, you'd have to say why and lie about the why.
4. you remember that song from 50 years ago when you were in bell bottoms and platform
shoes, and today your ears have enough wax for a 12 hour candle, and your hearing
can't hear the difference between a bass fiddle and a triangle. that's why the song sounds terrible.
5. someone puts on music that makes you suicidal and you are polite enough to say the
recapping made it sound like crap in order to escape.
6. some boutique caps sound like crap only in your recap or in every unit. and sometimes
the more expensive it is, the boutiquers are too embarrassed to say it's crap caps.

here's to recapping everything crossing your path, fixing it for the next 10/20/40 years so
you can enjoy the music

 

[ScottFan355]

Well, I'm glad this is settled once and for all. Now we can get back to arguing about speaker wire.

Nah it’s all about the interconnects man!

 

[gslikker]

Do not take away the joy of capacitor chitchat using a topic which contains the "final conclusion"
To keep things alive, we need opposing conclusions and fortunately a lot of them are on AK
Otherwise, there is no need for a forum and things get boring.

 

[432HzBob]

So I have a question too,
Without doing a full recap on a unit, is it worth it to just do the PS and output caps (the big ones and ones nearby) instead of doing a full breakdown recap?
Does this reduce the strain on all the rest of the smaller ones ahead in the line?

 

[gslikker]

I have more than one valid answer to both questions, to be applied in any order....

- yes
- no
- it depends
- ymmv
- if it satisfies doing less than half the job avoiding the recap or not question....

 

[gadget73]

Without doing a full recap on a unit, is it worth it to just do the PS and output caps (the big ones and ones nearby) instead of doing a full breakdown recap?

To be honest with you, I've had less trouble from big caps than small ones.

Anyone notice when buying caps what the life in hours is?

just bear in mind that rating is with everything at max ratings, so temperature, voltage, ripple current, etc. Under non-extreme conditions it will last a whole lot longer.

 

[Hyperion]

So I have a question too, Without doing a full recap on a unit, is it worth it to just do the PS and output caps (the big ones and ones nearby) instead of doing a full breakdown recap?

If you only mean the 'large can' capacitors in the PSU and the large output coupling capacitors, (in the case of amplifiers with capacitor coupled output stages), this may improve things a little. But note that contrary to what some people think, the large can capacitors in the PSU have an easy life, and are usually well behind the other smaller capacitors in terms of age related degredation. So, rather than being the first capacitors you should think of changing to see an improvement, they are actually the last. The caveat here is the case of an amplifier used consistently at very high output levels or a 'Class A' amplifier, whose heat output and current requirements particularly at idle are much higher. Both of these scenarios will very likely degrade components like electrolytic capacitors much faster.

Does this reduce the strain on all the rest of the smaller ones ahead in the line?

It might do just a little, in the case of 'local filtering' capacitors, which remove ripple and noise on individual, often seperate, sections of circuitry.

 

[ConradH]

So, at what year should a total recap be done?

"Once and for all", not too sure it will stick!

 

[Oerets]

When replacing a bad cap in a crossover does one just replace only the bad?

Or just do them all?

I was never in the just recap camp until completing a Marantz 1070 that was purchased new. One I plan on keeping and also have in another original condition. Day and night difference. Blind tested with three people who knew nothing other then what sounded better. Same CD player same CD same speakers used for testing. Used a selector box and it was unanimous in favor of the recapped. So the other was done with the same parts.

No burn in it was just after completion of work done.


Barney

 

[Gibsonian]

Year 20 consider
Year 25 strongly consider
Year 30 do it

 

[Oerets]

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