Hi All,
My newly acquired receiver is experiencing a loss of output/distorted condition in the right channel when powering up after being dormant for a period of time.
This condition exists when the volume knob is at a 9 o`clock or earlier position.
Raising the volume above the 9:00 position clears the condition completely and the will remain that way until the next time it is powered off.
I`ve deoxit`d all the potentiometers, output relay and switches as best that I can. Power supply voltage, DC offset, and idle currents have been adjusted and are stable, the unit sounds very nice.
I`ve narrowed the issue to the power amp section by running the preamp outputs to the amplifier inputs via the external jacks. I`m led to believe the issue may lie with a faulty capacitor in the signal path of perhaps a semiconductor.
What would be a suitable plan of attack at this point?
Thanks in advance 🙂
My newly acquired receiver is experiencing a loss of output/distorted condition in the right channel when powering up after being dormant for a period of time.
This condition exists when the volume knob is at a 9 o`clock or earlier position.
Raising the volume above the 9:00 position clears the condition completely and the will remain that way until the next time it is powered off.
I`ve deoxit`d all the potentiometers, output relay and switches as best that I can. Power supply voltage, DC offset, and idle currents have been adjusted and are stable, the unit sounds very nice.
I`ve narrowed the issue to the power amp section by running the preamp outputs to the amplifier inputs via the external jacks. I`m led to believe the issue may lie with a faulty capacitor in the signal path of perhaps a semiconductor.
What would be a suitable plan of attack at this point?
Thanks in advance 🙂
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It really does sound very much like the output relay at fault. Its a classic fault with exactly the symptoms you describe.
You need to open the relay and draw some paper soaked in cleaner through the contacts.
Turning the volume up allows enough current to flow to temporarily 'burn' a way through the oxidation layer on the contacts... until next time 😉
You need to open the relay and draw some paper soaked in cleaner through the contacts.
Turning the volume up allows enough current to flow to temporarily 'burn' a way through the oxidation layer on the contacts... until next time 😉
sounds like a plan.
The issue persisted even after running a Deoxit soaked cardboard between the contacts. I then started probing the relay while engaged and sure enough, the third contact appeared to be the culprit.
I removed the retaining spring at the top of the relay and removed the moving contact assembly to have clearer access to the contacts and ran a clean fine grit nail file very lightly across all contacts followed by a shot of cleaner. Not only did the right channel come to life immediately but I`d say the left channel sounded even better 🙂
All was still good after powering down for several hours. If I dont revisit this thread the problem can be considered solved.
Thanks guys
I removed the retaining spring at the top of the relay and removed the moving contact assembly to have clearer access to the contacts and ran a clean fine grit nail file very lightly across all contacts followed by a shot of cleaner. Not only did the right channel come to life immediately but I`d say the left channel sounded even better 🙂
All was still good after powering down for several hours. If I dont revisit this thread the problem can be considered solved.
Thanks guys
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