Yamaha CR-1020 Makes popping sound, loses sound, then comes back on.

BTW most of the electrolytic caps in your photo's show signs of heat stress ie. Shrunken plastic sleeves and rounded aluminum tops.
 
Both channels. I am refering to Left channel and right channel. Not Speaker A or B or C. Left is going to be left no matter which set you select.

Yes, the popping is in both the right and left channels. When it goes off temporarily, it also goes off on BOTH channels.
 
Tap around on the top, front, LH side, power supply board. Listen for Pops or other noises. Sounds like cold solder connections. Or a transistor acting up.

You were absolutely correct. I tapped around in several different places on the top, front, LH power supply board and got popping noises each time I did it.
 
Lightly tap on individual components. Wiggle the two heatsinks a tiny bit, Lightly tap on the relay. To somewhat narrow down your field of search.
 
That corroded resistor lead could be the issue if the corrosion is severe enough.

I'll do that Monday morning.

I did find a cold solder joint on the power board, the molex connector that connects the two boards. Three of the five pins have cracks around the solder joints.

Also, the service bulletin I read recommended changing the resistors near the large capacitors and resoldering that very same connector .
 
I've bought some of the 4 and 5 color band resistors before, but these don't have color bands. What all information will I need to identify these to order new ones?
 

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What all information will I need to identify these to order new ones?

Look at the printed silkscreen under the resistors and/or the text printed on the resistor. ( 22Ω 150ma)
Using Ohms Law calculates to almost 1/2 watt (.495 watt)



The 2020 service bulletin requires 2 each 22Ω /3.25watt and 2 ea. 33Ω /3.25watt "Ohmite's"

Surprise..Ohmite still makes those odd power values.

https://www.mouser.com/ProductDetail/Ohmite/93J22RE?qs=sGAEpiMZZMtbXrIkmrvidIY3c6LmoosbW8%2bArvubKUE=
https://www.mouser.com/ProductDetail/Ohmite/93J33RE?qs=sGAEpiMZZMtbXrIkmrvidNoLDMO5CJt8WrVD/BNh/hc=
 
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The CR-2020 and the CR-1020 share the same power supply boards. Yamaha engineering determined that the CR-2020 needed larger wattage resistors.
 
FWIW - I have the exact same problem with my CR-1020 - intermittent cutting out of both channels. I had to move it out of my basement and I swapped it with my office system, and the cut outs stopped for a while, but now am getting the intermittent popping. I now notice just tapping on the case now makes it worse, so it is most likely bad connection or solder joint. I'm restoring some speakers right now, but when done will swap with my CR-620 and track the problem down.
@avionic - thanks for the many Yamaha tips including the ones above. Have seen elsewhere that it may be solder joints on the power supply board / electrolytic cap board. Will check it out soon...
 
I have the same problem and found it to be the module in plastic case that the screwdriver is pointing to in the pic. Does the plastic case come off to access the wires and solder joints to check them? Thanks!
 

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I have the same problem and found it to be the module in plastic case that the screwdriver is pointing to in the pic. Does the plastic case come off to access the wires and solder joints to check them? Thanks!
That is the protect relay. Solder connections are on the underside of that circuit board.The best fix is replacement..
 
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That is the protect relay. Solder connections are on the underside of that circuit board.The best fix is replacement..
Replacement of the entire circuit board? I'm new to this and haven't had to work on it since I bought it back in the 70's. Thanks for being patient.
 
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