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Repair Help Yamaha R-90

F

felidispat

New Member
They say three house moves equal a house fire. Well my old Yamaha R-90 endured two moves over the last five years, but finally quit on the third one. It powers up; all displays light up (tuner, equalizer, source selection indicators etc) and all buttons work. BUT there is no "click" that would follow a few seconds after power up, and there is no sound, not even the slight rustle I'd sometimes get turning the volume knob.
I have a multimeter and the service manual with schematics, but I don't know where to begin, or really how to read the schematics.
There is no hifi repair shop near me, so I gotta do this myself.
Any help is appreciated.

Many thanks.

Here be the schematics:
https://drive.google.com/file/d/1o_hcBQJbf0xhAzmM1PbVWI2OuacCCr5q/view?usp=sharing
 
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Update:
I located the speaker relay (RLY401) and opened it up.
It reads 53V DC on one of the contacts and 3.6mV on the other. (taking the chassis as negative)
When I manually close the relay, I hear a hum in my left ear (using headphones) but its silent on the right.

Where do I go from here?

Again, many thanks.
 
Moving really has nothing to do with it unless you banged it real good a couple of times. All my stuff has survived 5 moves but then again, I am very meticulous about my stuff and I transported everything myself except the speakers (had to use a friends truck).

The 53 volts means that one channel has DC on it and is most likely a shorted output transistor. It can happen at any time. Maybe it was ready to let go at one more power up. :dunno:

Different voltages in different houses with only a few volts difference can sometimes wreak havoc on electronics. Just ask my Phase Linear amp. :D

Damn dude! You signed up in 2012 and are now asking a question. :D
:eek2:
:beerchug:
 
Last edited:
Hehe. Guess I'm a bit of a lurker. Didn't have anything specific to ask about all these years.
Would the output transistor be upstream or down from the relay? Please note that I'm as noob as it gets in these things. I can fix a lot of agricultural implements like a champ but electronics are a new frontier for me.
 
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