Power Supply Cap Question

[RCAkid]

I received a bunch of NOS parts from Moyers to repair my CTC-47 and recap that and my CTC-21.

Included in the parts are the big multi section can power supply caps for both chassis.

I wanted to double check my thinking on this but should I bring the chassis back up on a variac after replacing these caps? Do they need to be formed or are they good to go after replacement.

Just thought I would double check.

On a side note, this was my first experience with Moyers and they were absolutely awesome to deal with. So knowledgeable and easy and yes...FUN to work with. Got a whole box full of goodies to make repairs with.....just thought I would comment on them.

Roy

[Findm-Keepm]

Yes, ALWAYS reform old electrolytics. The variac method is best, short of using an LCR meter that can reform them, like the Sencore LC53/75/102.

Cheers,

[marty59]

It's just a safe habit to bring anything up with the variac after some work! There's always some forming to take place on virgin electrolytics that have never seen a voltage before.

[Chad Hauris]

You might not want to hear my opinion but I would never reuse old electrolytics! If they sat around on a shelf they may be even worse than those that have been in constant use. I would just get high-quality new ones to make sure you get the longest life out of your repair job.

[radiotvnut]

Originally Posted by Chad Hauris

You might not want to hear my opinion but I would never reuse old electrolytics! If they sat around on a shelf they may be even worse than those that have been in constant use. I would just get high-quality new ones to make sure you get the longest life out of your repair job.

I'll second that. Whenever possible, I just leave the old cans in place (disconnected) and wire modern individual sections under the chassis. Sometimes, space does not permit and the can must be removed and a terminal strip mounted on top of the chassis for the new capacitors. This may not be the most authentic method; but, it's safer than using 40 year old caps. Besides, those old cans are generally a pain to replace and why go to that much trouble installing something that could blow up and destroy other parts in a short time.

[zenith2134]

Thirded. For certain, old 'lytics are ticking time bombs. If you're gonna do the job, may as well make sure it stays done.

NOS capacitors are not like NOS tubes. They have a shelf life and are often in bad shape out of the box all these years later.

I've had good luck disconnecting old can caps on old tube stereo amps (the above chassis caps which provide a certain visual appeal to the design) and mounting newer caps underneath. The good thing about new caps is that they are physically smaller for a given rating most of the time.

[andy]

000

[Findm-Keepm]

Originally Posted by andy

The questions is how old are the NOS caps? If they are from the 80's, or newer they are probably fine, but anything older won't be much better than the originals. Personally, if they test good for capacitance, ESR, and leakage current under full voltage, I would use them, but I don't mind going back in to re-replace the occasional cap.

Now, if you're re-capping for the sake of having all new caps, then you need to use new caps. Replacing the old caps with more old caps won't buy you anything unless you're just replacing the bad caps.

Agree - I'd rather stick a USA-made Mallory, CDE or Sprague from the 80's in my sets than a Korea/Taiwan/China made cap. Just too many "gray market" caps out there to be sure, and the old Mallory caps (1973 date codes, so replaced sometime or another...) in my CTC-16 have better measured ESR and leakage than the newly-purchased Sprague TVA (Taiwanese made) replacements I was going to use.

Interestingly, the CDE's (WBR series) that Mouser sells are the only USA made caps I have found, outside of the exotic audiophile caps that command 40-50 dollars each. Xicons are nice, but the 105 degree ones aren't available anymore. The CDE WBR's will still set you back 15-20 bucks a piece. A NOS, 80's made Mallory FP multisection cap can be had 20-40 bucks. The hard part is finding one with the correct or close values.

Can anyone recommend a USA-made 450V cap that's easily obtained and fresh?

Cheers,

[andy]

000