Kenwood KA-7100 -- less volume in right channel

[gurdyp]

Hi all,

So I have a Kenwood KA-7100 amp. I bought it fairly recently from a guy who swore that all the cleaning, etc, had been done.

Just the other day I realized that the volume is starting to go (it's a bit less and perhaps slightly distorted) on the right channel. I am a total non-techie person — but willing to learn! — and I'm wondering if this would be a relatively easy fix?

I have done some searches here on AK for this kind of information, but the threads seem to be people doing a complete overhaul and it gets very technical.

I'm just hoping someone out there might give me an idea if this is a fairly simple problem to fix, or if I need to go to a technician for this?

I should mention that I was thinking of selling the unit, and would have got quite a premium price here in Montreal, because the market is always moving and the unit is in very good shape. But now I have this problem with the volume on the right channel...

Anyway — any and all advice most appreciated! Thanks!

 

[sanjib]

Clean all switches very well with Deoxit. If it is easy a fix it will do. If not first you have to isolate whether the problem is in pre-amp or main-amp. This unit does not have a separate Pre-amp and Main-amp port in the back so it is not easy to find where the problem is. To do that you need a scope and signal generator and then feed signal to AUX and check the pre-amp out at pin 10 and 8 on the tone board, if the signal is fine there your problem is most probably in the main amp If the signal is distorted there the problem is in pre-amp. The reason can be leaky capacitors or noisy transistors.

 

[rickl]

Clean all switches very well with Deoxit.

^^^this. don't forget the selector switch. I have one in my work room and once cleaned, the channels should be balanced.

 

[turboyam]

Did you try to invert the source channels (right in left)?. Do you have the same results on MONO and REVERSE?. Try cleaning the attenuator switch again. If you do the pots, use Caig FADERLUBE F-5 NOT deoxit!, deoxit is for the switches.

 

[cheapcuts]

I had the same model that sounded like the output relay was close to failing. It turned out it was an aging transistor that switched the relay on was failing.. I replaced the transistor with a modern variant as suggested and the relay was suddenly fixed! I am not a tech. Lucky for me the repair was easy to find in my case. I just found the info on the web a few years ago under kenwood ka 7100 repair or some such search. Good hunting. It was located in the middle of the board, easy to get at but visually not close to the relay..There is a posting on youtube under (Jorden Pier) kenwood 7100 no sound, no relay click, that gives lots of info. Qe34 on the schematic was the culprit in that case. Unlike the youtube poster I would replace it with the modern iteration of the same physical size of transistor as there may be some needle nosed pliers and leg bending required , or not, it was a while ago. I think google makes old info on this disappear like my grey cells.