Kenwood 7100 Right Channel Issues

[apn408]

Hi all -

I just purchased my first piece of vintage audio equipment so please be patient with me as this is completely new!

I just got a Kenwood 7100 integrated amplifier and noticed that the right channel will either get very quite or will get scratchy and cut out. I've found that increasing the volume quickly will kick the channel back on, but it's never a sustainable fix.

I've run this under a few different settings to give more detail on what could be going on - I've tried these after the right channel falls off:

Mono - right channel still out
Stereo - right channel still out
Reverse - right channel still out

Balance all the way to the right - no / very little sound from right channel

I've tried both the Aux and Phono input so I don't think it's an input issue.

I've noticed that if I keep the volume up, this issue is less likely to manifest.

Thanks in advance for the help! Looking forward to learning more about this amp!

 

[mbz]

Mono - right channel still out

Indicates the problem is after the mode switch, it could be the switch itself but you would be unlucky.
Try with tone defeat on.

The extra volume needed to "breakthrough" is often a dirty switch/relay/... could also be a lazy transistor.

Suggest check bias as per sm, just part of general house keeping, also try headphones, might be a dirty speaker selector.

Some test equipment would help, don't "spose" you have an oscilloscope or can build an audio probe, quite simple, I've
posted instructions previously, do a search..

Welcome to AK, it's a nice amp, worth saving.

 

[apn408]

Thanks for the quick response. Right now I’m just testing the amp with headphones as I don’t have passive speakers to hook up yet.

I assume i should start by opening it up and clean up the pots and switches?

After I use the amp for around an hour or so the right channel issues subside, but I do notice the right channel isn’t as clear or is slightly scratchy sometimes.

 

[Grenadeslio]

Thanks for the quick response. Right now I’m just testing the amp with headphones as I don’t have passive speakers to hook up yet.

I assume i should start by opening it up and clean up the pots and switches?

After I use the amp for around an hour or so the right channel issues subside, but I do notice the right channel isn’t as clear or is slightly scratchy sometimes.

Excersize the controls, by this I mean operate the switches rapidly on /off 30 - 40 times isn't too much. Do the same thing with the knobs, this is a temporary fix but should get things going for some time until a proper cleaning can be performed.

 

[mbz]

Try with tone defeat on.

Any improvement with tone defeat on?

I assume i should start by opening it up and clean up the pots and switches?

Start with speaker selector though could be others like mode,,, and also pitted contacts on the relay

 

[rickl]

one more thing, unplug the unit, open the cover and use your favorite contact cleaner on the controls. Don't minimize Grenadeslio's post. you need to work each switch many times while using your contact cleaner. Looks like the speaker selector is the first place to clean. then move on to any scratchy pots (volume, balance, bass, treble, ...). You will also need to wait a but *after* you are done cleaning before plugging in. Go slow and have fun!

I'd suggest not turning it up full volume with something not working. you want to keep the magic smoke in.