Does anyone have a schematic for the Motorola Mark II AM Radio that came in my '74 Valiant? I need to change the amplifier Biasing.
I'm going to replace the burned up Germanium 2n176 PNP Final with a Silicon final. It appears that the biasing circuit is damaged.
If I could get a copy of the shematic, that would help. Then I can figure out what's broke.

CJ

Give me some more information. The Chrysler part number off of the paper tag would be great. I can check if the neighbor has the schematic in his collection of Sams Photofacts.
I did find a schematic for the AM/FM version of that radio in Sams Photofacts at a public library, but that library is 60 miles away from me.

I had one of those radios in my 1975 Valiant that worked intermittantly, it was the main output transistor that is on the front of the radio. Later I had an AM/FM version and the sound was distorted. That uses a pair of output transistors (instead of one like the AM version) and one of those transistors was bad.

What you need is the Sams Photofact book for your particular manf. & part# on the radio. They include repair info and photos showing where the parts are as well as schematics. I was very pleased with mine. I got them from: http://www.agtannenbaum.com/

I don't know if they still have copies, but I'd ask them. You can also try http://www.samswebsite.com/
directly.

It is important that you get the correct manf. & chassis model#.

As far as I could tell, Chrysler didn't issue schematics for their radios and treated them as a black boxes. I've been told that Chrysler threw away all their old info. Motorola would never answer me when I tried to get schematics from them.

The actual transistors# I needed were obsolete, but generic replacements worked just fine. I just used my old Radio Shack cross-reference book to find something even close.

The tag reads as follows:

3501 622

Motorola Mark II

Serial 337299 2PD 1306

66254

CJ

Some Moapr radios had the schematic on the inside of the radio cover, but I imagine you've already checked that.

Yes Sir,

Not there. Would've been nice!

CJ