Stewart-Warner 9000-B schematic

[PaulOF]

Hi,
I'm looking for a schematic for a S-W 9000-B. Nostalgiaair has an alignment guide but no schematic. Nothing on BAMA. The Philadelphia public library has a lot of Sams' stuff on microfilm, I'll try there soon, but many of them are not well photographed (super high contrast and poor exposure don't really work well together). Anyway, if any of you know of anything, I would appreciate hearing about it.
Paul

[bandersen]

There's a schematic in the 1946 Beitman's on page 137. I've attached a copy in pdf format. Good luck.

[PaulOF]

Thank you so much.
Paul

[DavGoodlin]

Regarding the schematic, part labeled 43 - .02 mfd capacitor feeds back to screen grid G2 on the 12SQ7 first audio tube. Some Zenith radios have this also.

Question 1: Is this de-emphasis feedback to increase low-frequency response?
Question 2: RE Part 38, Often the 35L6 audio output cathode resistor can be bypassed (paralleled) with a 100mf-16v capacitor to increase bass. Does part 43 accomplish this?

[Reece]

1. The negative feedback from the secondary of the output transformer to G2 of the 12SK7 reduces distortion.
2. Bypassing the cathode resistor of the output tube with an electrolytic can increase available volume, but introduce some distortion. SW chose not to do that in this case as they went for better overall sound using part 43 for negative feeback.