KA-92B Amp not outputting left channel

[Cricketgg7]

Hey y'all, I've been all over the web and made an account here hoping for some assistance.

I'm trying to set up my parent's old Kenwood system and running into a block with the KA-92B stereo amp. I'm not getting any audio or signal into the left channel at all, on either bus.

I've 2 speakers and tested them both with different wires and tested most of the rca inputs with different devices, and I can confidently narrow it down to the amp itself having the issue. The headphone output also only gets the right signal, btw.

I've noticed on the decibel meter that I get a light on the right channel but not the left, regardless if any input/output is plugged in.

This system hasn't been used in quite a while, 20+ years at least, so I'm unsure if wear has caused any issues. But I'm wondering if this is a common enough issue that a new cap or transistor can fix.

The only workaround I've found is plugging both speakers to the right channel on the 2 busses, but that's obviously just a doubled right signal, not a mono setup by any means.

Any advice would be much appreciated.

 

[rickl]

Welcome to AudioKarma!

tape monitor work for both channels?

i skimmed the schematic and you could try cleaning the switches.

20+ years is a long time sitting unused. maybe a cap failed.

you will need to download the schematic (see hifiengine) and check the PS voltages.

if the ps voltages look good, Does the relay click after about 5 seconds?

if not, measure the anode and cathode of D17. I think this will turn on the protection relay.

if relay doesn't click, post voltages on IC5. be very careful not to short any pins. pins 2 look like the sensing voltage. if pin 2 is not 0, your channel is probably bad and you will need to either send it to a tech or start learning the joys of electronics.

it may not be worth sending out. not a lot of value in these 100 w/c integrated amps.