1980 PANASONIC RX-5120LS..no tone output on right channel

[Wes125]

i restored this a while ago. but i just noticed there is no trebble output on the right channel. it was working fine when i bought it.its only noticable when you turn the trebble right up as you can hear it more on the left side. ive replaced the caps on the volume tone control circuit board on the top right and switch cleaned the contacts.and i removed all the plugs inside and cleaned every contact pin. so i know its not a dirty contact causing it.. but there is still no tone at all to right speaker..does anyone have an idea whats caused this to happen.because i've never come across this problem before

 

[Transistorized]

Willing to bet it's likely the tone slider. They can fail at any time even while sitting. The tone control likely is two tracks. One for left channel tone and one for right, even though its one single slider. Internally it's stereo for tone control. The side the tone isn't working on has had its contact come loose from the slider internally causing it to not adjust tone on that side. But before taking it apart to TS, I would test the slider with a volt meter to confirm what I am telling you is true. At this point, it's merely speculation on my part but if it were on my bench, that tone slider would be on my radar.

 

[Transistorized]

Same thing happens with the JVC.

Below is the treble slider that I removed to repair the slider on the one side that wasn't working. You can see the idividual "fingers". One for each channel. The plastic nylon slider has tiny stems that, after the metal feeler is placed down on, they melt to hold it in place. After a while those tiny plastic retainers break off and the finger simply falls off.

M70.

 

[Wes125]

Same thing happens with the JVC.

Below is the treble slider that I removed to repair the slider on the one side that wasn't working. You can see the idividual "fingers". One for each channel. The plastic nylon slider has tiny stems that, after the metal feeler is placed down on, they melt to hold it in place. After a while those tiny plastic retainers break off and the finger simply falls off.

View attachment 56891View attachment 56892M70.

thats for ya help i will check out the slide control