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Yamaha C-80 right channel issue

C

Carl J72

New Member
Hello, another newb here, I recemtly purchased a C-80 off the bay and discovered that the right channel suddenly drops out after a few minutes of listening. Some of the capacitors appeared to be in questionable condition, so I replaced all of them hoping I might get lucky... no such luck! After reading several threads on here, I spent some time tapping around to see if i could locate a week solder joint, again no luck. The only thing I have been able to determine is that when the channel drops out, a simple power off and back on brings back both channels for another few minutes and then the right channel drops out again.

Many thanks in advance for any suggestions
 
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Welcome to AK.
What source are you using?
 
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Check your solder connections for the volume and balance controls
 
Does TONE by pass button have any influence on the missing right channel.
 
Could be a transistor in the muting circuit with a bad solder connection or failing under load .. TR314,316 or TR332.
 
Update on my findings thanks to some better lighting and magnifucation has revealed some rough looking parts near the heatsinks. Those resistors run hot, obvious by the heasink, but perhaps spread to the adjacent connections? Not sure if this is the cause of the right channel dropping out, but might as well replace suspect parts while i have it open.
 
Carl J72 said:
Those resistors run hot, obvious by the heasink,
Click to expand...
Have a close look at R271 & 272
- 4.7KΩ 1/4 watt Usually have corrosion damage from the slop over of the heatsink glue.. These are power supply resistors that would influence both channels. But non the less need to be addressed.
 
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I removed the resistors, they were starting to crack and fall apart, cleaned up the PCB, i will keep looking at the other items you listed.
 
The front panel tactile switches can be intermittently problematic on one channel or the other sometimes.
 
Channel dropped out, so I carefully changed input from AUX to DAD without turning off, both channels working. So perhaps the issue is with the AUX input??
 
Carl J72 said:
So perhaps the issue is with the AUX input??
Click to expand...
Solder connection on the AUX input jack or a flaky front panel tactile switch...perhaps..
Hook back up to the AUX input and wiggle the jack a bit..Or exercise the AUX button a couple dozen times.
 
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