Kenwood KR6160 right channel weak and distorted

miloweb

New Member
Hello new to the forum, I have a Kenwood KR6160 the right channel distorts and any volume and not loud, both channels work through the headphone jack fine, I was thinking of replacing the 4 2SC1115 transistors, am I on the right track? This is from any source too.
 
Welcome to AK.

Suggest try and localize the fault as pre or power amp stage using the PRE-OUT/MAIN IN RCA's.
It's probably a power amp issue. Connect another amp/ipod/iphone or whatever at minimum volume to the MAIN IN RCA's
and check for right channel distortion. Alternatively you can use a pair of RCA cables but cross them, ie, Left Pre out
to right main in, and Right Pre to left main. If problem remains on right channel then power amp suspect.
 
Power amp Qe1,2,3,4 are listed as 2SC458LG, these have a bad history of going noisy. Replace with KSC1845 or KSC1815
depending on current needs.
 
While replacing the 2SC458s is a good idea, note that the driver transistors - which are 2SC693s - were a common failure point on these amps (I've restored several of them). Problems there are consistent with your symptoms. I don't think the issue is with your output transistors, since your headphone output seems to be working fine.
 
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While replacing the 2SC458s is a good idea, note that the driver transistors - which are 2SC693s - were a common failure point on these amps.

The schematic lists Qe1-Qe4 as 2SC693, but the KR-6160 that I restored had 2SC458 :eek: transistors in those locations, so I'll put in KSC1845F.
 
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I looked at my spreadsheets from those two restorations. Both of those had 2SC693s. In both, I used KSC1845s.

To the OP: I would test the drivers before messing with the outputs (altho pulling the outputs, cleaning off the old thermal compound and replacing it would probably be a good idea).
 
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Thank you for all the replies. I tried the main in and same distortion. just for the heck of it I pulled each of the 2SC1115s, and only one had 0 resistance between the base and emitter posts (could be the culprit?). maybe replace the others mentioned above as well?
 
Sounds like you have blown output transistor(s). Buy four of MJ21194G and don't forget mica insulators and thermal grease like Thermalcote.

Mica insulator for TO-3 (TO-204) transistor packages: Aavid part number 56-03-8G
Aavid Thermalcote: Avvid part number 250G
 
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And you will probably want to determine why the outputs got blown in the first place. Bad emitter resistor? Driver transistor(s) went bad? Bias resistor, trimpot or varistor go bad?

If you just replace the blown outputs and not the reason why they blew, you risk blowing the new outputs.
 
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Interesting that the headphone output is not affected. I thought I remembered this receiver as not having a separate headphone amp....must be getting old and confused (or, more precisely, even older and even more confused).
 
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