Yamaha CR-640. No relay. Where to go next?

Clean up that blue area with alcohol or acetone. Inspect the transistor solder connections.

provide another photo of that transistor solder connection. Put some light on the subject.

It looks like some cold solder connections..
 
avionic said:
Clean up that blue area with alcohol or acetone. Inspect the transistor solder connections.

provide another photo of that transistor solder connection. Put some light on the subject.
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I did this after taking the pic. I did continuity tests and it seems ok. I can desolder/resolder but all seems ok.
 
With the unit unplugged.. Measure the resistance between the R907 and the anode side of D804. One end of R907 should read 180 Ω the other end should be zero Ω's or shorted.



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What does your meter read if you short out the two test leads ?
 
Recheck for DC voltage on R907 make sure you have a solid electrical connection on the resistor with your meter lead.
 
avionic said:
Recheck for DC voltage on R907 make sure you have a solid electrical connection on the resistor with your meter lead.
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edit: something is wrong here. I measure 14 vac on the resistor lead facing the edge of the board and 1.7 vac on the other lead. Very small mv dc on each lead.
 
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I think D803 has failed. In circuit using a diode test on DMM it reads .002 both ways. D804 reads .6v + lead on anode, OL + on cathode.
 
da_kube said:
I think D803 has failed. In circuit using a diode test on DMM it reads .002 both ways. D804 reads .6v + lead on anode, OL + on cathode.
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That is likely what killed C813. Polar electrolytics do not play well with AC voltage...
 
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