[edison]

Hi.

I need help to identify one condenser in the Philco 39-116.
The condenser is in the volume control motor circuit and in the schematic, and the parts list, says it’s a electrolytic condenser, but I have doubts, because the capacitor has no polarity and is in an alternating current circuit.

Can you clarify if it is  a non-polarized capacitor or not ?

Please see the pictures.

Many thanks in advance.

Carlos

[Link]

Hi Carlos

   I believe it is a 30 uF, 30V electrolytic. It may be constructed to use the case/chassis mount as a neg lead default. How it is constructed can only be installed one way. 

   I have found Philco has built a lot of circuits that make you go huh, yet they all work. If it is in a motor control circuit, I'd guess it was there to steady out the drive from electrical noise. I am definitely not an expert though. 

Cheers, Link

[morzh]

I am not quite sure what an electrolytic polarized cap is doing there.
Is it direction switch?
The current / voltage there is AC and it is bad for a cap.
Back then there were no small size non electrolytic caps of this capacitance so it is probably an electrolytic.
I do not know if by chance it is non-polarized electrolytic.
They did the same in tweeter drive in 38-690, using an electrolytic cap in crossover AC out.
This said, replace it with the same capacitance/voltage film cap.

[gregb]

I would go with a non-polarized electrolytic, I have done a number of RCA motorized sets and that's what they used on the motor. As Morzh stated above standard electrolytic's do not like AC.

Gregb

[edison]

Tanks Link and morzh and Gregb.

This picture is more enlightening.

Cheers, Carlos

[Link]

Ahhh, now I see two leads!! : )

[morzh]

It didn't denote + or - anywhere, did it? The sch shows a polarized cap. But if no marking prrsent, it might be a non-pol type, just don't know how available those were at the time.
This is purely academic interest, the cap should be either nonpol electrolytic or film.

[edison]

Hi.
The two wires are identical and there is no polarity mark.
I assume it is really a non-polarized capacitor.
There is another data that leads me to assume this, which is the inscription of 60 cycles that is written on the capacitor ... I have never seen this on electrolytic (polarized) capacitors.

Cheers.
Carlos

[morzh]

I tried film caps....too large.

Mouser has bipolar/nonpolar aluminum caps.

https://www.mouser.com/ProductDetail/Nic...QPnjphw%3D

Here's one.

[edison]

Thank you.
I will do with two electrolytic capacitors in series.

Cheers.
Carlos

[morzh]

Do not do this, it is wrong.
Two back-to-back (not in series, serializing makes for polarized cap) caps do not make a non-pol electrolytic.
It only works for DC where you could bias the centerpoint (if two minusses then to GNd, if plusses then to power).

[edison]

Thank you, for the explanation.

Best regards,
Carlos

[Nathan Slingerland]

The 1942 parts catalog lists the 30-2361:

   


http://philcoradio.com/library/download/...201942.pdf

Sadly no info other than it is a motor start cap as others have surmised.

[rfeenstra]

there you go, Nathan! Is it a split phase motor that requires a run capacitor?