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Sansui big capacitor replacement - disappointment

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mplsbob said:
Anyone have a suggestion for the cap replacements and where I might find some?
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80V and 90V are values not readily available in a screw terminal cap.

Are these 80V caps power supply caps? Or output coupling caps? If these are power supply caps, measure the voltage on the originals to see if you can safely drop to a 75V cap. If so, a lot of high-quality caps are then available.

Otherwise, you'll have to go to a 100V cap, and the number of choices do down.

It is very hard to make recommendations unless we know what the caps are doing in the circuit, and what the expected voltages on them will be.
 
Kjell-B, I agree with you regarding the sound difference between caps. But all modern caps are not sounding bad. You just have to find out what you like. I have two QRX-3000 and one QRX-9001 to experiment with, and compare two identical boards with different caps is very effective if you want to compare caps. BIAS current and some of the transistors and resistors are also important for sound quality. The difference I'm talking about is, just a very good sounding amp or a live concert in your living room, if you have a good recording.

/Goran
 
I suppose some component of this conversation involves professional ethics or professional practice. That's important. Since many AK members are DIY people, however, I think the whole recapping issue is much less inflammatory than it would seem in this thread. The parts are inexpensive. The remaining components of a recap job--the knowledge gained from each other and the time each of us puts into it-- cost little and can only further our own education and help build a community of people who appreciate well-made and well-maintained audio gear. :yes:
 
Guys, lets all get along here. There is no need to sling insults back and forth and escalate the situation.

restorer-john said:
My position is simple, if the cap tests fine- leave it alone.
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John, this is a very key point to a lot of us hobbyists or to budget minded audio consumers. How do you test them to be sure they are good today and will remain good over time?

I also hope you see that when you refer to others on this board as "so called experts" you are basically saying they are ignorant and you know better. I don't think that is always the case.

- Pete
 
Someone please recap only one channel of a 30+ year old piece of gear and let us all take turns blind testing it at the next AKFest :)
 
Recapping a single channel to hear the difference is an interesting idea, but may not reveal more subtle differences, like an altered soundstage.

Assuming I am in attendance next year, I can offer a pair of Kenwood KA-7100's one in stock form, and one fully recapped by Echowars, but someone else may need to ante-up a listening room.
 
True, recapping one channel, I envisioned two speakers and the amp in mono mode, for rough evaulation only. You would need two amps of the same model and production run otherwise, to test stereo, and a speaker switching box I assume so that you dont have to doublestack also-identical sets of speakers. Could get hairy.
 
Glenn, we've both been members of this site for virtually the same time. I am stating a fact here, the same postings on the same subject keeps coming up with the same responses- none of which tackle the issue. Capacitors are just one of many components all susceptible to failure. Not only that, many people cannot test the caps properly, don't own an ESR meter and really have no idea whether they are OK or not. I have seen hundreds of postings where the standard response is 'recap the amp' when the problem is clearly unrelated. I like you, use good quality caps and where possible original caps whenever I replace, but blanket replacements are not clever (and may merely obscure the real issue), especially when 9 times out of 10, the 'restoration' doesn't involve all the caps because they are too hard for the 'tech' to find. My point is, why stop with the caps? The carbon/brass cap resistors or epoxy case/carbon resistors are a candidate too, as is every transistor. You know as well as I do the small signal T092 transistors shift their gain and noise characteristics more than most other components put together.
I know the real reason, caps are easy to replace. A novice with a soldering iron and a bag of caps and a day to waste, just may possibly fix the ageing amp with the hit or miss approach. Then again, he may also be convinced the amp sounds better too. How about some actual data here? I don't attack anyone, merely practicses that have dubious merit, no measured data before and after, little logic and are surrounded in a sea of self perpetuating folklore. :thmbsp:
 
Thank you for that well-reasoned and intelligent post. I may yet change my opinion of you.

I rarely (if ever) have suggested recapping as a panacea, or as the cure for all ills, but for the novice it gets him in there and familiar with the unit, and as long as a bit of care is taken is unlikely to result in making things worse.

Crazy, Google 'Electrolytic capacitor failure mechanism', and spend some time reading. There's your proof. In particular, Panasonic has a study with a nice chart showing the 'death' of the caps rising at an exponential rate once the EOL point is reached. I'll let you locate it.

RE: Your 881 thread. FWIW, I never doubted that the problem would be simple and straightforward to repair, and was quite happy to see that you had solved it. But I never, ever, suggested that you turned your 881 into a doorstop. I related my own experience repairing gear that had been previously worked on by novices (and the clueless), and others who were supposedly professionals. Many times the original problem would have been a 30 minute fix, but due to dumbasses who had no business opening up their own gear the issue was made worse by many orders of magnitude. If you read my comment and saw yourself in it, it was not my intention, but I can't help you there. Time to get over it.
 
Everyone has got to start somewhere. I picked up this hobby (and opened my first amp) less than 11 months ago. My first project was a total recap of a Sansui QRX-777. I admittedly am still a novice, however I really enjoy the process of replacing components and listening to the results of cleaned switches and pots, new capacitors, fusistors and the like.

At the time I was certainly a dumbass who had no business opening my gear but thanks to this forum (and practically this forum alone) I have now managed to completely replace every capacitor (and a host of other components) in every unit in my signature. I messed up beyond my realm of troubleshooting three times and promptly found a tech on this forum more than willing to profit off of my stupidity.

At the end of the day, I would not have done anything differently. The money I have put into new components and the time I have spent hunched over a bench inhaling soldering iron fumes and squinting at poorly reproduced schematics was well worth it.

I have been told to leave the work to experts, but I figure dumbasses like myself are tolerated here because we bring a bit of side income to the experts.

If you enjoy opening your gear and replacing parts, whether they make a difference or not on paper, or just to your ears, and you assume full responsibility for your actions, this is the best hobby (and forum) around!!
 
Gentlemen to avoid confusion there is now a need to state basic positions.
1. Replacing capacitors improves reliability.
2. Does this always improve the sound?

Number 2 is the crux of the discussion.

I am learning and enjoying this thread. Sometimes it gets a little hot, but hey it is not over the edge.
 
Give it another 10 years.. Its takes a while with vintage stuff but ultimately everyone agrees. Those pesky electrolytics have to go if you want a usable piece of equipment.

Steve
 
Ouch. I think it is time to listen to Stravinski the Firebird through my AR-10 pi speakers while I eat my vanilla bean ice cream.
 
back to the topic

1. Yes, replacing 30 yo components can improve reliability, these have a service life and it's not forever, I usually only change caps in the power supply circuit, and of course any that a close visual inspection show signs of failure, such as bulging, leaking, or heat damage. That dooes NOT equate to a wholesale change of everything with a c in the parts list on the schematic.
2. Always? nope, however it can fix problems such as poor tone quality, hum, etc. I have changed caps in my AU 999 and heard no differance after a day of soldering, at least I don't think there was any, hard to do an A/B when you do this....
Would I change fuel injectors?
Not in this forum, and the old woman that lives with me is just fine, again a differant forum.
Hard to compare a fuel injector to a capacitor....
Just my opinion...
Casey



reggaenaut said:
Gentlemen to avoid confusion there is now a need to state basic positions.
1. Replacing capacitors improves reliability.
2. Does this always improve the sound?

Number 2 is the crux of the discussion.

I am learning and enjoying this thread. Sometimes it gets a little hot, but hey it is not over the edge.
Click to expand...
 
When I get a unit in that exhibits signs of bad caps on a particular board, I don't waste a bunch of time trying to figure out which one it is. I'll change out $5 worth of caps rather waste an hour trynig to figure which one or two have gone bad. I might not re-cap the whole thing, it's a hard sell, but I will recap a whole P/S or amp board or boards. I've never had anyone tell me that their receiver sounded worse after they got it back.
I tend to think that recapping the amp, P/S or even the pre-amp boards is pretty unlikely to have a negative effect on the sound. We're not talking about the caps in speaker crossovers here, I'm pretty sure that the design makes the sound. I'm quite sure that guys who used to design amps for Sansui, McIntosh, Pioneer, ect. would say the exact same thing.
I would never, ever put 30 year old caps in a receiver as replacement parts.
 
I believe we were waiting to hear exactly which cap needed to be replaced, the voltage required (lower being better for selection purposes), and which part of the circuit it was in so we could rule out more caps. The 2200uf caps I have used in my restorations were in Sansui QRX-7001 / QRX-777 / TU-777 and I used the Panasonic THA/TSHA, which I understand would not be the best choice if we could get the voltage requirement low enough to be able to use FC caps or Nichicon
 
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