The PHILCO Phorum
Philco 41-226 Filter Cap Ground - Printable Version

+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: Philco 41-226 Filter Cap Ground (/showthread.php?tid=5367)


Philco 41-226 Filter Cap Ground - imacdaddy757 - 10-21-2012

Good morning, all. I'm working on a 41-226 "Sled" radio and need confirmation on the connections of the 20/20 filter caps.

I found that my note-taking failed due to the size of a 20/40/60 cap someone had jammed in there, making it hard to see where the connections went that I had to cut to get it out.

From my notes, one 20uf hot went to 35Z3 pin-7 cathode, the other to 35Z3 pin-4 with resistor #44 (220K). My notes say that ground of the filter cap was also at pin-4 which I know isn't right, but there is a stub at pin-3.

Can someone confirm that the ground goes to pin-3?

Regards,
Clarence

RE: Philco 41-226 Filter Cap Ground - rghines1 - 10-21-2012

Hi Clarence,

This radio uses a floating B- instead of using the chassis for a common negative return. Therefore the 20uf caps' negative leads do not connect to the chassis. On the 35Z3, pins 3, 4, 5, 6 are no connection based on the tube manual. They are likely being used as convenient tie points for resistors, etc..

Since pin 3 is no connection it could be used for anything.

Best to follow the schematic to insure all is electrically connected properly. Gets easier with practice.

http://www.nostalgiaair.org/Resources/396/M0013396.htm

RE: Philco 41-226 Filter Cap Ground - imacdaddy757 - 10-21-2012

Thanks. I'll find a place on B- but had hoped to put it back where it was originally.
Thanks for the prompt reply.

Regards,
Clarence

RE: Philco 41-226 Filter Cap Ground - imacdaddy757 - 10-23-2012

I got confirmation I can tie into B- at capacitor #39.

Many thanks.

Clarence

RE: Philco 41-226 Filter Cap Ground - Arran - 10-23-2012

The cathode pins of the 7B7 tubes are also connected to B-, all the way back to the power switch. Pins 1,2,7,8 are used on the 35Z3, pins 3,4,5,6 are unused and could be tie points for anything, there is no pilot lamp tap on a 35Z3 tube, the set parallels the pilot lamp with a series dropping resistor, part #48, which is a 53 ohm job connected between the hot side of the power line and the plate of the 35Z3, an 89 ohm resistor connects between the plate pin of the 35Z3 and one of the filament pins of the 35Z3.
There are only two filter capacitors in this set from what I see, the third on the replacement may be parallel connected with one of the other filters or it may be connected as a cathode capacitor on the 35A5 tube. Though this set did not have a cathode capacitor from the factory it was a common modification to improve the bass response of the power output stage.
Regards
Arran

RE: Philco 41-226 Filter Cap Ground - imacdaddy757 - 10-25-2012

That is a great help, Arran. I very much appreciate it.
Although it's a cramped little chassis to work in, someone put
a lot of forethought into its design. I'm expecting this little
6-tube radio to play especially well once I'm done with it.

It's clean and complete, and very original from what I see
(with the exception of the replaced filter cap). They'd not used the 60uf section of that cap, just the 40, 20 and the ground.

I'm lucky that the wiring is in good enough shape to recap it and do all my checks then try it out, without having to immediately rewire the whole set, as I had to do on the 39-30 I finished recently. A serious job, though it was a roomy chassis to work in. The results were great on that one, but whew, a lot of extra work. I'll replace a couple of easily reached wires for now in this one, and save rewiring for later. I'm trying to be careful not to disturb any more wires than I have to for now.
I'll see when I get to the last three caps in the corner beneath the 1st IF transformer (Item #25) - I'm betting I'll have to rewire quite a few things to get those three caps out, with insulation flaking off. Oh, well, still worth the effort. It's such a joy to bring one back to life.

Thanks again for your help.
Regards,
Clarence

RE: Philco 41-226 Filter Cap Ground - imacdaddy757 - 09-14-2014

Aaran, I got this set working beautifully on broadcast and SW. It pulls in stations crisply on SW, even without an external antenna. I much appreciate your help. I do need to replace the grommets supporting the variable cap to raise it enough so that the dial pointer no longer hits the bottom of the dial cover, then do some work on the cabinet finish. But that is all that's left. I'm very happy with this set. Thanks again.