Values for 2 can electrolytics in tuner chassis of AW 12 Deluxe

[Ken Carr]

I am working on my Scott AW 12 Deluxe.

I need to identify the values of the electrolytic capacitors that are mounted on the tuner chassis. They are not marked with values but each one has a dot of green paint on its base when looking from the underside of the chassis. These are the tall can capacitors.

 

One of them connects directly to the voltage divider resistor. In the circuit drawing this appears to be an 8 mfd and is the only one designated as electrolytic. The other capacitor connects to the second grid (pin 3) of the first IF tube, a type 58. I can’t tell from the Rider drawing which symbol is that grid. In any event it shows all 3 grids going to capacitors and none of the capacitors are labeled.

 

I am guessing that both capacitors are 5 mfd each due to the green dots. I’d rather not guess. Does anyone know the capacitance and voltage rating of these capacitors? Thanks.

[Kent King]

I have always replaced these with 4.7uf 450VDC caps. I'm not sure if any of the schematics give a value...

Kent

[David C. Poland]

I have a diagram for the 12 tube DELUXE AVC model that says 8 MFD for the the one at the high B+ end of the receiver's voltage divider. Doesn't say for the 2nd on the 90 volt tap, so I would use 8 MFD there too, but Kent's suggested 4.7 likely OK too.

[Ken Carr]

Kent, If it works for you it works for me. That sounds like a reasonable value.
Thanks!



Kent King said:

I have always replaced these with 4.7uf 450VDC caps. I'm not sure if any of the schematics give a value...

Kent

[David C. Poland]

The 2nd grid you mention for the several IF 58's is the screen grid and usually operates at a voltage somewhat below the plate voltage.

Traces to the 2nd tap (90 volts or so) on the voltage divider.

[Ken Carr]

Thanks, David. That is the same drawing I am working from. It s funny how vague it is. It's good to have confirmation from you and Kent that the record leaves something to be desired. It may be because they did such a good job of marking all those other capacitors they became dependent on the serviceman just reading it from the component.

David C. Poland said:

I have a diagram for the 12 tube DELUXE AVC model that says 8 MFD for the the one at the high B+ end of the receiver's voltage divider. Doesn't say for the 2nd on the 90 volt tap, so I would use 8 MFD there too, but Kent's suggested 4.7 likely OK too.

[David C. Poland]

I have restored a couple of Deluxes with AVC. Very sensitive. Very good action on the tuning meter.

The earlier twin speaker version sounds good. The later version pedestal speaker sounds somewhat better.

[Ken Carr]

Good to hear, David. This one has the pedestal speaker. I don't have it working yet but I will. The power supply is done except for the two non-electrolytic capacitors. I will do them after I figure out which kind of pop rivet to use to preserve the look of the old ones. For now I do get all the filaments to light. One tube was wrong (they replaced a 58 with a 57). I have a couple 58's on order. I am putting a little time into the cabinet now. It is a bit of a wreck. I am using lots of veneer and glue. 

Thanks again.