CR-2040 pop when turned off ONLY, not on turn on.

mr_light

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I have a CR-2040 that pops when turned off ONLY, not on turn on. Otherwise works perfectly.

I started this discussion in another existing thread with somewhat similar symptoms, but it's just causing confusion there so I have created my own thread to try to separate the discussions.

Things I have checked/adjusted:

Speaker protection relay delays for 3-4 seconds and then clicks (connecting the speakers)
+60 volt pin on one of the power amps and adjusted to 60 volts +/-1mV
Adjusted idle current to 10mV +/-1mV
Adjusted DC offset to 0 volts +/-1mV
Cleaned and lubed all pots (doubt that is related)
Inspected components looking for leaking/bulging caps or anything else obvious...

What else should I check?
 
It has blown two sets of 1 amp fuses on both of my "good" test speakers. Apparently the pop exceeds 1 amp every time on both channels. I now only have junk speakers attached.

I should mention I have a fully functional CR-2040 I can test for comparison purposes.
 
:scratch2:..Might have a real close look at that relay...ie burnt/welded contacts...Is there a arc arrestor across the power switch?Should be..:scratch2:
 
How to open relay to examine? Also might a speaker relay from a CR-840 work as a substitute (I have a couple of CR-840 donors). There is a spark arrester on the power switch (do they go bad?).
 
You have 840 parts donors? Hmm. Any chance you'd sell me a part or two?


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Send me a PM with what you need and I'll see what I can do. Never mailed international, but I guess I can figure it out.
 
Since the relay is open at turn on for the first few seconds I assume the contacts can't be stuck closed. I'm not sure how the timeing for when they open at shutdown is determined and how this protects the speakers. I did confirm that I have a spare identical relay from the CR-840 that I could swap in if needed.
 
I had the same problem. Shut down it would make a poping sound from both speakers. But on start up relay would click in after maybe 7 seconds and receiver would come on. This went on for approx 6 months. Now as soon as I put receiver on receiver comes on with no delay appears relay has stuck in the closed position. I was told not to use it untill repairs are made otherwise further damage can happen. I hope this helps Regards Dale
 
Does it POP with the coupler switch (rear panel) in the decoupled or seperated position?
 
I hooked up a separate amp to the Pre-Out jacks and I get the Pop through the external amp. Sounds like it isn't in the power amp section...

I can hook up the PRE-Out jacks to another power amp and see if there is a pop if that would serve the same purpose.
 
I would like to try a replacement spark killer Cap-Resistor. The schematic shows the specs as .033 Capacitor, 120 Ohm Resistor 125vac. Any idea for a source?
Would this work? "C5: OKAYA 0.2uF 120 Ohm 250V CAPACITORS-SPARK QUENCHERS"
 
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I would like to try a replacement spark killer Cap-Resistor. The schematic shows the specs as .033 Capacitor, 120 Ohm Resistor 125vac. Any idea for a source?
Would this work? "C5: OKAYA 0.2uF 120 Ohm 250V CAPACITORS-SPARK QUENCHERS"

Should do fine..
 
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