DO MICA CAPS EVER GO BAD? MY RCA RADIOLA MODEL 61-8 LISTS 2 MICA CAPS. ONE THATS 56 mmf, AND ONE THATS 330 mmf. JUST WONDERING WITH SUCH LOW VALUES AND THAT I HAVE NO TEST EQUIPMENT TO TEST THEM, IM WONDERING IF THEY EVER GO BAD AND NEED TO BE REPLACED?

:DO MICA CAPS EVER GO BAD? MY RCA RADIOLA MODEL 61-8 LISTS 2 MICA CAPS. ONE THATS 56 mmf, AND ONE THATS 330 mmf. JUST WONDERING WITH SUCH LOW VALUES AND THAT I HAVE NO TEST EQUIPMENT TO TEST THEM, IM WONDERING IF THEY EVER GO BAD AND NEED TO BE REPLACED?
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Hi Troy, they do go bad but it is rare. Probably the best thing to do is to change any electrolytic and wax/paper caps and see what you end up with. If the radio comes up and works you should be good to go. I have a BK 810B meter that checks them and they do have a tendensy to be out of tolorance but the radio works fine still. Got the meter for cheap off of Ebay. I like to check the replacement caps before I install them. The old electronics are pretty forgiving and will work even though they are way out of tolerance. I've had radios that call for a 20 mfd electrolytic and have a 100 mfd in place. I guess alot of old radio techs used what they had on hand. Best bet is to get a hand held cap tester. Best 2 U, George T

Sometimes what looks like a mica cap is not, ... such as those with the brand-name "Mica-mold".... those are typically bad if the value is .001uf or larger because they are really paper inside not mica.
So in general all "Mica-mold" brand caps are extremely suspect.

Now on the other hand EVEN regular mica-caps can often go bad too if the seal between the lead and the case is disturbed by flexing or such. Then moisture gets inside the plastic case and they oxidize or get leaky one way or another.

So after 70 years even mica-caps should be inspected or tested for leakage. (even changed out regardless)

I used to think that I didn't have to worry about them but I got caught with many intermittent leaky mica-caps that drove me nuts trying to find.

So it won't hurt to err on the side of safety and wasted time by swapping those out too... because, they are so darn cheap and it is a bit of insurance against the radio ever coming back to bench for repair!

If it is you own radio... you may chose to chance it but if it's a customer's radio.. I ALWAYS replace the mica-caps as well as all others.

:Sometimes what looks like a mica cap is not, ... such as those with the brand-name "Mica-mold".... those are typically bad if the value is .001uf or larger because they are really paper inside not mica.
:So in general all "Mica-mold" brand caps are extremely suspect.
:
:Now on the other hand EVEN regular mica-caps can often go bad too if the seal between the lead and the case is disturbed by flexing or such. Then moisture gets inside the plastic case and they oxidize or get leaky one way or another.
:
:So after 70 years even mica-caps should be inspected or tested for leakage. (even changed out regardless)
:
:I used to think that I didn't have to worry about them but I got caught with many intermittent leaky mica-caps that drove me nuts trying to find.
:
:So it won't hurt to err on the side of safety and wasted time by swapping those out too... because, they are so darn cheap and it is a bit of insurance against the radio ever coming back to bench for repair!
:
:If it is you own radio... you may chose to chance it but if it's a customer's radio.. I ALWAYS replace the mica-caps as well as all others.
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Hi Again, Peter that is some great advice, they are cheap and you are 100% right. The micas can cause you a lot of grief, best to change them while you are at it. George T