1950s TVS!, and tube radios!

[AiboPet]

GREAT pic of "look for any that look swolen...or are sitting oddly on the board" I had posted in another thread about a generic 5" set (forget where I posted that).

Your pic is a GREAT example of pretty much BOTH of those conditions. It's too bad only really these type of electrolytics do this very obvious fail. The rest....I am sorta having to GUESS..since I do not yet have a capacitor checker.

Is an "ESR" meter really even sufficient to test the "big" caps? I ask...because I have seen that in order to check a cap correctly, you have to be able to CHARGE it to it's rated voltage. No way the little ESR meters I see with (I assume a 9V battery) can do this?

I would get one for pretty much MOST the little solid state stuff I play with...but it seems not sufficient to have even a "good" meter with a capacitor checking section on the dial.

Unless of course...I am wrong. Most the little "micro" sets I work with have electrolytics (just like these in most cases)...rated to maybe 16v-50v or so. Only place I have been running into "big boy" caps...are the big old Sony solid state sets ("big" being relative....since my "big" sets are 9" sets). The Sony sets with these bigger caps almost ALWAYS exhibit linearity and horizontal stability problems. I tend to recap them in a "shotgun" fashion without being able to really check 'em.

[wa2ise]

Seriously, you need to replace the old electrolytic caps. They cost a lot less, and are easier to obtain than, a power transformer. Even the big multisection cap cans. You can use individual single unit caps to replace them. But don't just solder the new caps across the old caps, that won't protect you if the old caps short out (this is the failure mode to fear, this is what will ruin the power transformer). I've taken a hacksaw and cut the old can cap just above the crimp bulge (this is where the rubber gasket seal is housed), removing the old cap can and guts, and Ive drilled small holes thru the gasket and passed new cap leads from above to the terminals below. Some people will go to the trouble of carefully tucking the new caps inside the old can (after the guts are pulled out (nothing overly toxic, but don't eat it and wash your hands afterwards)) but I've just had the new caps out in the open (but take care to be sure they can't flop around and short out to something).

Flybacks and yokes and CRTs are also hard to find replacements for, so we also change out the caps around them as well.

I know, as a kid you probably have no real money to get this stuff, but you risk ruining hard to obtain parts.

[Tubejunke]

Originally Posted by AiboPet

Is an "ESR" meter really even sufficient to test the "big" caps? I ask...because I have seen that in order to check a cap correctly, you have to be able to CHARGE it to it's rated voltage. No way the little ESR meters I see with (I assume a 9V battery) can do this?

As a technician I wish that I could answer this question and would like to know myself what difference there is (if any) between an ESR meter and the capacitance mode of common DVOMs. There is no use to go buy an ESR if you can use your digital meter I would think. Even in college we had an ESR and nothing more, but I know that there is a tester that actually loads the capacitor. That is what I would think that any of us would want, especially since we are dealing with working voltages way above those found in modern equipment.

[peverett]

I agree with wa2ise, replace all electrolytic and paper caps. A while back, I restored a 1953 Emerson. There was one paper cap that was hard to get to. As it only had 4 volts across it(in the AGC circuit), I left it in. Guess what the cap failed in very short order, causing picture and sync overload. I had to go back in and replace it.

A more recent experience was with a 1958 RCA portable. In this case, there were some capacitors that were packaged like the modern orange drops, so I assumed they were still ok. No! I had to replace these to get correct vertical linearity and height(which would shrink as the set warmed up). I am not sure if they were paper inside or just heat damaged. Now I just replace these as well!

40 to 50 year old caps are no good. The technology to make good, long lasting capacitors was just not available then. (I am not sure it is available now for electrolytics!).

[lnx64]

Originally Posted by peverett

(I am not sure it is available now for electrolytics!).

Nope.. It just doesn't exist sadly.. Maybe longer than then, but not good.