I have a philco 40-195. As I am recapping, I took out a couple capacitors that are labeled as 1000 working voltage. Do they really need to be that high a voltage? These are on the lines feeding the output transformer items 72 and 75 on the schmatic.

In looking at the schematic there is about 215V across the caps. I've personally been purchasing 630 WVDC caps for recapping and haven't run into a problem yet. I wouldn't think you would need to put 1000 WVDC caps back in, unless I'm mistaken.

:I have a philco 40-195. As I am recapping, I took out a couple capacitors that are labeled as 1000 working voltage. Do they really need to be that high a voltage? These are on the lines feeding the output transformer items 72 and 75 on the schmatic.

I'm not to sure that you shouldn't try to replace them with 1000 volters. It's not so much the "normal" operating voltage but the spikes that can occur from static etc. PL

:In looking at the schematic there is about 215V across the caps. I've personally been purchasing 630 WVDC caps for recapping and haven't run into a problem yet. I wouldn't think you would need to put 1000 WVDC caps back in, unless I'm mistaken.
:
::I have a philco 40-195. As I am recapping, I took out a couple capacitors that are labeled as 1000 working voltage. Do they really need to be that high a voltage? These are on the lines feeding the output transformer items 72 and 75 on the schmatic.

There are very large AC voltages riding on the B+ here. Must people have the 630 VAC caps. Just double the cap (.003 x 2 = .006) value and put two of them (.006)in SERIES. This will double the working voltage to 1200 VAC.

: I'm not to sure that you shouldn't try to replace them with 1000 volters. It's not so much the "normal" operating voltage but the spikes that can occur from static etc. PL
:
::In looking at the schematic there is about 215V across the caps. I've personally been purchasing 630 WVDC caps for recapping and haven't run into a problem yet. I wouldn't think you would need to put 1000 WVDC caps back in, unless I'm mistaken.
::
:::I have a philco 40-195. As I am recapping, I took out a couple capacitors that are labeled as 1000 working voltage. Do they really need to be that high a voltage? These are on the lines feeding the output transformer items 72 and 75 on the schmatic.

Hi All,
I agree with Robert on the voltage rating due to the AC on the DC voltage. However, putting capacitors in series is an unreliable practice. The problem is that the capacitor that has the lesser leakage will take more voltage.
See page 1694 on the Digi-Key catalog, www.digikey.com. You will find plenty of HV capacitors.

Best Regards,

Bill Grimm

I see a lot of WVDC ratings much higher than I think that the cap would ever see,especially in audio tone control circuits(~1000 volt). I think that the manufacturer was looking for a higher quality and stability(safety?) in this stage of the radio circuit?And why just this stage? I just can't see this kind of 'overkill' where manufacturing parts costs are involved. As far as I know, even a transient spike that would cause a 'pop' in the speaker could occur in any portion of the circuit from the antenna on down where signal-carrying caps WVDC ratings are no more than a couple of hundred volts. I know that vibrator-buffer caps(~1600 volt) take a pounding from the arcing and AC hash that comes from the vibrator points, even though they are fed by only 6/12/24 volt sources,although into a large field-collapsing/back-EMF producing step-up power transformer-type inductor.In fact,it was recommended to replace this buffer-cap anytime the vibrator was replaced. Maybe I'm not taking into account the tremendous amount of amplification taking place along the stage train from RF to IF to AF? But seemingly nowhere near the WVDC ratings that the caps are provided with. I enjoyed the discussion on 'motor-start' caps last month.-Walt.

Modern polyesther or polypropylene dielectric capacitors have DC leakage resistances which are sometimes in the giga ohms. Basically a non factor. If there are slight variations in leakage or capacitance and therefore slight variations in the voltage across each capacitor, what is the concern? You can check this out by measuring the DC voltage across each cap for yourself. You'll find no appreciable difference. Even so it will not exceed the capacitors' working voltage. Therefore capacitors can be used as voltage dividers. As to reliability, I have used this for decades with on my own projects with no failures. It just makes use of less expensive components that you already have on hand.

:Hi All,
: I agree with Robert on the voltage rating due to the AC on the DC voltage. However, putting capacitors in series is an unreliable practice. The problem is that the capacitor that has the lesser leakage will take more voltage.
: See page 1694 on the Digi-Key catalog, www.digikey.com. You will find plenty of HV capacitors.
:
:Best Regards,
:
:Bill Grimm