Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12) x

Thread Closed
Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Philco 41-226 Filter Cap Ground
#1

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
#2

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
#3

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
#4

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

Many thanks.

Clarence
#5

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
#6

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
#7

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.




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Need to purchase some accessories for restoration of my Old Philco Radio
Here is a list of resources found in our online library that you might find useful. Mike's Gobs of Knobs email addres...klondike98 — 01:46 PM
First Radio restoration
Hi Tubeman, Welcome to the Philco Phorum.  Phamily Phriendly Pfun with Phine Pholks Phull of Philco Phacts. (See a p...MrFixr55 — 12:33 PM
First Radio restoration
You could post in the WANTED ADs section here on the Phorum and see if anyone has an RF generator that they want to sell...klondike98 — 11:55 AM
Zenith H725
Good ideas, thank you Arrange and Rich. I have the adhesive aluminum foil already and can try that immediately. More ...EdHolland — 10:18 AM
Graphics for majestic 1050 dial glass.
Murf; I found this thread on the ARF, the first photo has a pretty good view of the dial glass. Regards ArranArran — 01:12 AM
Zenith H725
hello Ed, how about that speacial tape used for ducting it's like foil or how about thin piece of aluminum roof flash...radiorich — 12:19 AM
Zenith H725
Ed; One material that I have seen, but never tried for this was material for making exhaust gaskets, it's similar to ...Arran — 11:42 PM
Zenith H725
I just remembered, I have some hi temp silicone rubber material which could do the trick. Or a piece of FR4 laminate. Th...EdHolland — 08:39 PM
Zenith H725
The PSU filter cap arrived today (thank you USPS!) so I will work on that later. Meanwhile, I have the dial, speaker...EdHolland — 06:42 PM
Philco 610B oscillator wiring
Thanks Terry. After checking my notes I think I recorded about -10v at the 6A7 G4/control grid. The screen grid (G3 &...Tubester — 05:59 PM

[-]
Who's Online
There are currently no members online.

>