Cute KA-4000 Help

OK. Back for help now.

I deleted the OP 'cause I did not go thru the regular troubleshooting steps first.

So, here's what I got. A low left channel output. This is what I did:

Cleaned all switches and pots.
Took the plug-in boards out, and cleaned the finger contacts.
Took the Pre/Amp jumpers off and cleaned each and the RCA's on the amp.
Looked for a poor or cold solder joint. Found none.
Checked for bad caps or resistors. Everything looks OK.

Someone has been into this. 1 transistor has been changed. I'll assume the other 3 (RCA's) are original. They are all #2N3055's, but the replacement has no name on it. It has a square box with a S (?) or 5 (?) on the lid, then the part number. Anybody know the brand? A google search got nothing.

I also noticed that the replacement has a ceramic wire wound resistor (about 2inches long) from 1 leg to the other transistor's leg. Plus, there's white heatsink grease behind the insulator (?) on both.

The other side with the 2, has (what looks like to me) a carbon that is much smaller. No grease on those. Just the insulator.

Should I be looking to replace the transistors (all?) with new, or do you guys think it's something else? BTW, I removed the Pre/amp jumpers and went straight into the amp with another Pre I have. Same results. Left side low.

Any guidance would be appreciated.

Thanks.
 
OK number 1 --- try to get a service manual. part #'s etc should be there with schematics etc. and assembly drawings help too.

Num 2 --- one of the switches could be dirty still but that "FIX" you describe sounds suspicious. You need to know where those parts are in the signal path.

That should be a good start ..
John M
 
Thanks John.

Just so EVERYONE understands, I am a TOTAL NOOB at this. :yes:

OK. So that's out of the way. I don't want to lead anybody on that I know what I'm looking at. I have a little knowledge, VERY little. :D

I can take things apart. I can solder. I can put things back together. I follow instructions well. Now, as far as test equipment, I have a very good meter that does all the basics and also has hfe, cap and coil capabilities. I mostly use it for x-over builds. No scopes.

I thought I narrowed it down alot by running the amp off another Pre I have. This is why I thought it might be the "repair" someone did. The only other things (with my limited knowledge) in with the amp (by it's self) is the on/off-speaker selector, and the input selector. All the rest of the controls had no effect when just using the amp.

That's all I got. BTW, I have the service manual. I'll be looking it over tonight. Still thinkin' it's the "repair".
 
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