ONKYO AVR401: distorted sound in one channel

[TB]

Hello,
My trusted ONKYO amplifier for the past 17 years started to act on me two days ago. When I turned it on and play music the right channel became distorted. After few minutes it comes back to normal. I did not open the case yet. An amplifier is old, but I have never problem with it. Can those be electrolityc capacitors?

Thanks for the help.

 

[TB]

Just for amp details... this is solid state two channel integrated amplifier. AVR stands for audio-video. The amplifier has just additional inputs for VCR to route the signal. This is what would be called now very simple amp with no gimmicks. I just can not afford now to buy a new one. I would like to try to fix it by myself. At first I thought that could be capacitors in PSU. But, if that would be a case it should affect both channels, is not it?
I did try to serach the forum, but some questions were not answered. It looks like this is common questions for older amps.
Thanks again for help.

 

[TB]

Any input?
At least where to start to look?
Thanks

 

[Mooly]

Could be an electroylitic or an old ceramic cap going leaky. It's impossible to guess though.
Is the amp DC coupled to the speakers ? If so does any DC offset appear when problem occurs ?
Does it do it on all inputs... ie is it a power amp problem or not ?
Does it respond to tapping or probing the PCB with a plastic tool indicating a poor soldered joint.
Speaker relays ? these can be a source of distortion as the contacts oxidise, particularly at low volume.

 

[TB]

Thanks Mooly. I will try to test it this weekend.