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HELP WITH YAMAHA C-80 PRE AMP no sound!!

avionic said:
Common (-) lead to a good chassis ground and probe voltages with the red (+) lead..Probe with red lead and meter in DC volts.Be very careful you don't inadvertantly short anything with a slip of the probe.If you don't have mini-grabbers,I would suggest some electrical tape wrapped around the probe tip leaving just the very end exposed.
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gotcha ,!!

will let you know my findings after i am done ..

Gary
 
avionic said:
Black common (-) lead to a good chassis ground and probe voltages with the red (+) lead..Probe with red lead and meter in DC volts.Be very careful you don't inadvertantly short anything with a slip of the probe.If you don't have mini-grabbers,I would suggest some electrical tape wrapped around the probe tip leaving just the very end exposed.Or heatshrink tubing.
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ok have the top of the amp ... if looking at it from the front which side is the r500 resistor having a hellva time finding it .. don't seem to see any r*** only d*** i'll keep looking ..

Gary
 
In the service manual.You can locate the parts using a the circuit board layout print.But ..this pdf sucks..Stand by I'll see if I can locate a better one.
 
avionic said:
In the service manual.You can locate the parts using a the circuit board layout print.But ..this pdf sucks..Stand by I'll see if I can locate a better one.
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thanks ... i see it is common with one side of d 324 .. would it not be 15.6 volts there too ??

Gary
 
Page 11 of the service manual I sent you. R500 sits right in between the two large electrolytic caps on the Tone control board. R499 is OK if you have the LED's lighting up.
 
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If you can make out the color code it should be yellow-violet-gold. 1/4 watt
 
Did you get +/- 16.5 volts on them. R500 should have been -15.6v there abouts.If so..Measure the emitter and base voltage of TR341.
 
avionic said:
Did you get +/- 16.5 volts on them. R500 should have been -15.6v there abouts.If so..Measure the emitter and base voltage of TR341.
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yea it was a negitive voltage ... sorry had to go to bed .. i am at work right now and will continue when i get home ...

once again thanks for all your help !!!

Gary
 
well sent it into my not so local vintage audio repair shop .. I'll keep you all posted on the repair ...

thanks Dave for all your help !!!



Gary
 
well,
she is back from the shop
2- 10ohm 2 w resistors were open
2- transistors were open
and 2 leaky zener diodes

150 bucks later she is all better ...

i think it is money well spent the is my first vintage set up and wow !!! this has been the best money spent !!!!! what an awesome increase in sound quality from using my old luxman receiver for a pre amp !!

thanks Again fellas

Gary
 
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