High Voltage Ceramic Cap Replacement - Videokarma.org TV - Video

TinCanAlley · #1 10-02-2013, 12:59 PM

Okay to make sure I'm covered in parts I may need, I'm trying to buy all the high voltage ceramic capacitors used in my set (as well as the resistors). The only problem, Mouser doesn't seem to carry what I'm looking for. They have the values, but not the voltage. Are these caps like electrolytic in that you can go to a higher voltage for the replacement? For example, I need a .01 1.5KV. Mouser has a .01 2KV. Would that work?

Also, I need some 600pf 10% 2KV ceramics and I can't find them. Well I can if I want to buy 10 of them from a seller on ebay. Would come out to about .80 each, but I don't know the manufacture or quality of them.

Also, what are the odds of one of the large ceramic resistors needing replacement? Like the 500ohm 7W on the tripler? Should I consider them for replacement or do they have a good track record?

Thanks!

TinCanAlley · #2 10-02-2013, 03:23 PM

Another couple of questions.....

Since these caps are used for decoupling and one leg is always on ground, do I need to discharge them or are they automatically discharged when the power to the chassis is removed?

Is it better to test them with an ESR meter, a Capacitance meter or both? With the ESR I can leave them in circuit (no power to chassis). I figure that if I get a bad reading then I should pull it for further testing. If it test good with the ESR, then it's most likely good. Am I going wrong with any of that?

Electronic M · #3 10-02-2013, 05:25 PM

Most ceramics are reliable. The rule that you can replace a cap with one with a higher voltage rating goes for basically all types of capacitor. If they are suspect I'd recommend getting an eye type capacitor checker like a Heathkit C-3 (though most of that vintage need a recap them selves).

StellarTV · #4 10-02-2013, 05:32 PM

You can't check ceramics with an ESR meter; ESR meters check the condition of electrolytics 1uF and above, generally.

Never had a problem with a capacitor with such a low uF rating holding a charge that was worth writing home about. If there's any charge left in the circuit after powering off and unplugging, it's going to reside in one of the large electrolytic filter caps.

TinCanAlley · #5 10-02-2013, 05:38 PM

So if most of the caps are decoupling caps, do I have to lift one leg to get a good reading from my capacitance meter?

StellarTV · #6 10-02-2013, 05:44 PM

Yes. It's a craps shoot otherwise and you usually won't get an accurate reading in circuit.

TinCanAlley · #7 10-02-2013, 05:57 PM

Quote:

Originally Posted by StellarTV

Yes. It's a craps shoot otherwise and you usually won't get an accurate reading in circuit.

Thanks! Not going to be much fun as they have short legs and are set into solder filled terminal strip legs.

zeno · #8 10-03-2013, 06:53 AM

Yes use a higher voltage. Disc caps dont go often. When
they do the often burn or they have cracks in them. Low
value caps that are non disc can be quite troublesome.
Discs are very high tolerance, others often low.
Maybe the cap man can pipe in, I am no cap pro.
I tended to learn what I need then stop at that.

73 Zeno