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Yamaha CR-620 Channel Drop Out

JB8

JB8

Well-Known Member
Fresh off the heals of a great repair on an HK 430 Twin, I'm back at it with another CR-620.

Unit was very dusty upon arrival, cleaned interior and Deoxit pots, etc. Looking much better. Before dusting I did a quick test to establish a baseline and found two issues:
  1. Slight amount of sound/signal with volume knob at zero for FM and AUX, did not test with Phono signal
  2. Left channel only kicks on once you get to around 9 o'clock, stays on for a while, then fades out. You can then fiddle with the knob - back to zero, back up to 9 o-clock plus, but the left side eventually fades away even if cranked up higher than 9 o'clock
All four of the unit's dial and meter lights are out, red LED's for power, etc, are all working. I've read that the lamps and protection circuit/relay are run from the same supply, so I'm not sure if this is contributing to the issues (?).

After cleaning the issues persisted, have not replaced lights yet.

The only other thing I've done thus far is to replace C715 and C716. During testing if I leaned on C715 a bit the signal would drop out, so I replaced them both and upped the voltage to 50. Lastly, TR802 had some schmutz around its base that I cleaned off. Dark and crusty, looked like it had been fluid at some point, but none of the caps in the area look funky.

I'm going to avoid replacing any additional components before actually determining the issue!

Thanks in advance for your help here, always appreciated.


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JB8 said:
Left channel only kicks on once you get to around 9 o'clock,
Click to expand...
Protect relay contacts most likely.. Check the voltage printed on the side of the HC2 relay..
 
Last edited:
Thank you, @avionic. When I rocked the relay I could get the left channel to kick on, right channel then crackled a bit as well, so definitely on the right track. Initially I simply refreshed the solders but still didn't get a solid, confident contact for both channels, so I took it out. (On the first Yamaha I picked up nearly two years ago you helped me with a similar issue and I ended up mangling one of the solder points, had to install a jumper and it worked like a charm, but now I'm extra careful to make sure I'm not creating more issues than I started with)

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Looks like this is 12 vs 24 volts, is this the part I'm looking for?

https://www.digikey.com/en/products...2/252217?s=N4IgTCBcDaILIE0wFoAMKAiBhAjBAugL5A

And perfect on the lights - the three on the meter/signal housing and the pointer will be easy to replace, I've got both incandescents and LED's that will work. I've used LED's on some of the CR-420's, do you advise against them or are they fine as long as they're installed properly?

Lastly, makes sense on the dried up glue...
 
Awesome, thank you Sir! I always appreciate your help.

I'll update this thread once the part arrives and the issues are resolved.

Thanks again!
 
Update:

New relay installed, no more drop outs for the left channel. Still have low level, balanced volume at the zero position. When I start to turn up the volume I get a 60/40 split, heavy on the right side. If I crank it up to 50% the volume eventually equalizes across both channels. Does this sound like a potentiometer/wiper issue or are there other paths to explore before considering a replacement of the vol/bal pot?
 
I've been doing more reading around this issue, seems like getting a new alps potentiometer is likely the best solution.

For replacements, do other CR's share the same configuration or are there aftermarket options to look to as well?
 
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