The PHILCO Phorum
Ecap help - Printable Version

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Ecap help - OldRestorer - 03-10-2015

unknown maker radio. 2 ecaps in cardboard box. One goes to chassis and pin 4 or 5 of the 25L6. Other goes to a terminal strip and pin 3 of the 25Z5. Any ideas?

Kirk

RE: Ecap help - PAradiogeek - 03-10-2015

If you have the tube line up we might have a shot at identifying the radio. From there we can sort out the caps.

Here is link that might help you identify your radio based on the tubes.
http://grillecloth.com/sylvania/tubelist.php

RE: Ecap help - OldRestorer - 03-10-2015

Here is the link.

http://grillecloth.com/sylvania/tubelist.php?comp=&mod=919&Num=5&tube1=6q7&tube2=6a7&tube3=6d6&tube4=&ball=Bm49c&Submit=Submit&db=3

RE: Ecap help - OldRestorer - 03-10-2015

I have found that before but zero other info

Kirk

RE: Ecap help - PAradiogeek - 03-10-2015

Are you saying you have the schematic?  If not, I have Riders 8-4 and can send you a screenshot of it.

RE: Ecap help - Carl Travis - 03-10-2015

Schematic 8-4 shows the C20 containing 4 electrolytics.
http://www.nostalgiaair.org/Resources/831/M0001831.htm

RE: Ecap help - PAradiogeek - 03-10-2015

Yeah, either this schematic is the wrong one, or the radio has been worked on previously.

RE: Ecap help - OldRestorer - 03-10-2015

The Ecap block looks original to the radio but only 4 wires coming out of it.

I will have to cross reference the schematic with the radio when I go back to the house.

Thanks for the link too.

It is a clock radio but the clock would not be on the schematic right?

Kirk

RE: Ecap help - morzh - 03-10-2015

One of you radios I worked on last summer had that.

Just trace the wires.
The caps are likely to be 20uF and 10uF, if the radio is an AA5 set without doubler rectifier.
The voltage rating can be 250V as there is no step-up transformer.
The max you could get fom 120V is 168VDC before you load it.
Once loaded it is much lower.

RE: Ecap help - PAradiogeek - 03-10-2015

The 4 wires would be the + lead of each cap. My guess is that there is probably a bracket or something similar that mounts to the chassis to provide the common ground.

RE: Ecap help - OldRestorer - 03-10-2015

I thought that too but nothing. There are 2 screws holding the box on but i did not see a ground strip or anything else. I will peel the cardboard tomorrow and see.

Kirk

RE: Ecap help - Radioroslyn - 03-10-2015

Do two of the wires go to the same place? If so then that may be your common ground.
Terry

RE: Ecap help - OldRestorer - 03-10-2015

All 4 go somewhere different Terry.

One to chassis, one to 35L6, one to a terminal strip and one to 25Z5

Kirk

RE: Ecap help - morzh - 03-10-2015

Wll, one minus to chassis, one pls to after rectifier 25Z5, then there is field coil, and one plus after the field coil (at the output transformer and likely the screen grid of 35L6
The fourth minus is the one I am not sure where it goes. But it goes to that terminal strip, and it is likely to be some low ohms resistance to chassis.

RE: Ecap help - Arran - 03-11-2015

 First something isn't correct here, the set can't have a 25Z5 and a 36L6 tube, one has a 300 ma heater and the other a 150 ma heater, and this is a series string set. So either it uses a 25L6, 25A5, or a 43 for an output tube.
  Unfortunately I can't read the schematic thanks to this P.O.C computer, but in any event four wires coming out of that condenser box could mean a couple of things. One could be that the set uses a fixed bias supply, like one in a pre war AC set, where one filter cap has it's negative connected to the most negative point in the power supply and the second one has it's negative end connected to a slightly less negative point usually to a resistor running between that point and a more negative one. Another possiblity could be that the included some paper caps inside that box, like large bypass caps.
Regards
Arran