I now own an 8 Track player

So I just found an 8 Track Player.....

 A Prinzsound CRD8, Serial # 001429 (thanks man)

I spent a bit of time on it to get it going nicely and it does now. Information on it is very sparse to the point were the above post was the only reference I could find on it.

I want to do a fairly complete post on the fix so that web can preserve the info in case others need it:

I opened the case and the hardware was all quite good. Heads nice and not even very dirty. Only one drive belt in the whole unit and that still has good tension. The power plug was loose so I tidied that up and plugged it in. 

No smoke or bad smells. Plugged in a David Cassidy 8-Track (the tape I cared least for was picked for testing) and it thumped into life ( really does thump. Big fat solenoids ) and plugged my 70 Technics EAH-220 headphones in.

Right channel fine, left channel nothing.

Got to be the rec/play switch. Stripped and cleaned with iso. No difference. Made a quick and dirty audio probe with a guitar amp I had to hand and found the signal disappeared in the left pre-amp just before the volume. 

No service manual to be found anywhere on the web. 

Drew a circuit and overlay then put it back together and started checking voltages on the left channel against the right. Second transistor in the left channel sus; replaced the 2SC871 with a BC549 . Sound in both channels but the left starts quietly then fades to full volume after 10 or so seconds. Replaced various electro' caps to no affect until I looked at the what I had considered the least likely electro which was the cap to the playback head. 

Replacing that fixed it and it now runs just fine. It was quite obviously swollen on removal and had interfered with the bias of the first transistor until the cap in the emitter path had charged up. Finally I put RCA plugs on in place of the DIN plug.

I'll post the overlay and circuit diagram I worked out in as follow ups to this post.

The only real lasting damage is that I now quite like David Cassidy. 

 

PC board overlay: Solder side.

 

 

Circuit diagram of the left channel :