[Eric Adams]

I'm working on a 48-482 and I've run into a problem. The only schematic I have been able to find shows a 6SQ7 as the first audio even though all sets have a 7B6 in its place. I have a tube diagram for the 7B6 but it would sure be a help if I had a schematic that shows the 7B6.
Does anyone know where I can get one?

Thanks,
Eric

BTW. The problem is: squeal like feedback when turning up the treble control and with a long wire antenna I can only get one local station all over the dial. Has been re-caped. Tubes and resistors replaced as nec.

[codefox1]

Schematic here
http://www.nostalgiaair.org/PagesByModel...013637.pdf

Tube data here for 6SQ7, 7B6 and anything else you wish.

http://www.nj7p.org/Common/Tube/SQL/Tube...?Type=6sq7



Both tubes do the same thing, and often whatever was available was used in production and changes were not always documented.

[Eric Adams]

Thanks Codefox1, The schematic is the same as I have but the tube digrams are much clearer. Everything checks out at the 7B6. I guess it's back to the trouble shooting guide.

[Sean]

There is a factory service manual for this model on this page although it also shows the 6SQ7. It is in DJVU format so you will need a reader.

http://www.audiophool.com/Philco.html

[Eric Adams]

Thanks Sean, that's the info I have now. I'm looking for something that shows the 7B6.

Eric

[LASJayhawk]

Eric, AFAIK all the published prints show the 6SQ7, but the only difference is the pin numbers. That said, this weekend when I have some time, I'll pull a working chassis and take some voltage and resistance measurements. Maybe we can pin down the problem that way.

[Eric Adams]

Thanks John, hope to hear from you soon.

Eric

[EagleRiverMike]

6SQ7

https://www.nj7p.info/Tubes/SQL/Tube_que...?Type=6sq7

If this link above doesn't work, go directly to NJ7P's website and enter the tube your looking for

Tube Database Website:

https://www.nj7p.info/Tubes/SQL/Tube.php

[GarySP]

The schematic in the Philco Radio Library accessed at the bottom of the Home page shows the 7B6.
https://philcoradio.com/library/index.ph...year-book/
Take care and BE HEALTHY! Gary

Thought I'd point it out, even though the thread is 11 years old!

[Ron Ramirez]

EagleRiverMike,

Welcome.

I use Bill's (NJ7P) SQL tube database query all the time - it's much easier than getting out one of my tube manuals.

But I should mention this thread is 11 years old, and the OP (original poster) hasn't visited here in nearly two years (I hope he's ok).

[GarySP]

Guess Ron and I commented simultaineously! Take care and BE HEALTHY! Gary