Variac or not?

[Phil Nelson]

I will chime in with Chimes and say you should replace the electrolytics FIRST, then bring it up on a variac.

You know that you should replace them anyway. Why not do it now?

I have had very poor luck reforming old electrolytics. Even if they seem to function, I would not bet my power transformer on them.

Others may have had different experiences. For me, all it took was burning up one power transformer.

Even if the TV kind-of sort-of works after bringing it up with the original electrolytics, what does that really tell you? You still have a TV full of rotten old caps that need replacement, so you may as well get started.

Just my $0.02,

Phil Nelson

[jeyurkon]

Originally Posted by Phil Nelson

I will chime in with Chimes and say you should replace the electrolytics FIRST, then bring it up on a variac.

You know that you should replace them anyway. Why not do it now?

I have had very poor luck reforming old electrolytics. Even if they seem to function, I would not bet my power transformer on them.

Others may have had different experiences. For me, all it took was burning up one power transformer.

Even if the TV kind-of sort-of works after bringing it up with the original electrolytics, what does that really tell you? You still have a TV full of rotten old caps that need replacement, so you may as well get started.

Just my $0.02,

Phil Nelson

Well, your 2 cents is worth a lot because you have a lot of experience and you've been kind enough to share it with others. I've found a lot of useful information on your web site.

I promise to keep track of any failures of electrolytics that I decided to keep and about how many hours they were in use before failure. I will post each failure on this forum. Hopefully I won't have to embarrass myself too often.

John

[peverett]

I agree with Phil. I tried re-forming electrolytics on a couple of AC/DC radios that I restored. No transformers to fry, but after 6 months the radios were humming again. I now just replace the electrolytics.

[jeyurkon]

I meant for this to be about bringing a TV up on a variac. I believe many do that even if they have totally recapped a set. I'm sorry if it's veered into an electrolytic capacitor aging issue

With the radios I've restored I have completely recapped them. I have a 60's radio that I've done nothing with and it's still playing and a 50's communication receiver that I've also not touched, other than realignments, and it works well. Of course it only has a couple of electrolytics and no paper caps. I've had it before I was a teenager.

I've purchased multi-section axial electrolytics off of ebay with the intention of restuffing them to use in some old radios I have. Although I didn't care if they were good or not the seller claimed they had been tested and reformed. However, he didn't know about testing for ESR. All of the ones that just had paper tubes to seal them had extremely high ESR. The others tested out well. I suspect that any electrolytics that seem to reform and then later fail may have had already marginal ESR.

The ones that I've kept in the set I've tested out thoroughly and are not in sections where they are under much strain.

My temperment is such that I question everything and have a need to check things out for myself. I may be making a big mistake, but I wish to see how long electrolytics, that test better than the brand new and fresh electrolytics that I had intended to replace them with, fair.

John

[Chimes]

I guess I don't see your concern. You say you have already recapped the set, so the next step would be to bring it slowly on the variac and watch for anything unusual. If it comes up and no smoke or fireworks, then time to trouble shoot any problems there may be.

I have never bothered to reform any new electrolytic capacitors and never had a problem and I have replaced hundreds. I hear the audio folks talk about that as they seem to think capacitors need to be "broken in", but with modern electrolytics that is simply not necessary.

[jeyurkon]

Originally Posted by Chimes

I guess I don't see your concern. You say you have already recapped the set, so the next step would be to bring it slowly on the variac and watch for anything unusual. If it comes up and no smoke or fireworks, then time to trouble shoot any problems there may be.

I have never bothered to reform any new electrolytic capacitors and never had a problem and I have replaced hundreds. I hear the audio folks talk about that as they seem to think capacitors need to be "broken in", but with modern electrolytics that is simply not necessary.

I'm not perfect. I could have put one in reversed. The schematics don't show the correct polarity for all of the electrolytics which adds to the confusion. If I bring it up slowly I might catch such a mistake before serious damage occurs.

Or, I could have a solder splash that I missed.

The errors in the schematic don't surprise me. While repairing my Sony STR-V55 receiver I discovered four electrolytics that were not only shown backwards on the schematic, they were installed that way at the factory. Fortunately these only see 10mv since they bypass the emitter resistors.

John