CR-820 Distorted Audio from one channel

[sajjad amer]

I resurrected this receiver with help from this forum. It was working perfectly when I decided to change the capacitors in tone control board with "Audio Grade" Nichicon.
I took out the last 10uF 16v capacitor and replaced it by error with 47uF 50V.
I checked the receiver after each capacitor replacement due to my previous issues and it was working fine till this last capacitor replacement.
Now when I play music, there is clear sound through Left , but Right side is completely distorted. Although there is sound, bass is much more pronounced on right side.
I have replaced all the new capacitors with old ones in tone board, it did not work, I have put deoxit in all controls , gave it a good wiggle and left it over night, problem still remains.
Can anyone please guide me in the right direction, I will never ever open this receiver again, its jinxed

 

[sajjad amer]

Forgot to mention the sound is distorted via both headphone jacks as well. Thanks

 

[OMGCat!]

That cap wouldn't have caused any damage especially in the tone circuit. I would very carefully inspect all of your solder joints to make sure there are no solder bridges or a stray blob of solder shorting two terminals out.
Also double check any wiring if you had to remove any connections to access the board.
If you can't visually find anything wrong it's time to break out the oscilloscope or signal tracer (I use one of those cheap chip amp boards from eBay for this purpose) so you can follow the signal in from the jacks and find out where it goes wrong in there.
Either way I doubt you've done any harm to the amp, it's most likely something small.

 

[avionic]

Is this the same unit ?
http://audiokarma.org/forums/index.php?threads/restoration-help-yamaha-cr-820.809115/

 

[avionic]

Is it still distorted with Tone defeat selected ?

 

[sajjad amer]

Is this the same unit ?
http://audiokarma.org/forums/index.php?threads/restoration-help-yamaha-cr-820.809115/

it is indeed, my nightmare. You very kindly helped me to sort it out but I wanted to put "audiophile" caps and messed it up again.

 

[sajjad amer]

Is it still distorted with Tone defeat selected ?

Yes it is I am afraid.

 

[sajjad amer]

That cap wouldn't have caused any damage especially in the tone circuit. I would very carefully inspect all of your solder joints to make sure there are no solder bridges or a stray blob of solder shorting two terminals out.
Also double check any wiring if you had to remove any connections to access the board.
If you can't visually find anything wrong it's time to break out the oscilloscope or signal tracer (I use one of those cheap chip amp boards from eBay for this purpose) so you can follow the signal in from the jacks and find out where it goes wrong in there.
Either way I doubt you've done any harm to the amp, it's most likely something small.

Thank you for the tip and reassurance. I have downloaded 100hz sine wave signal in .wav format, from http://onlinetonegenerator.com/ and use it from PC to look at Oscilloscope.
I have noticed that signal is not distorted till volume control/balance switch. So that has to be the culprit. I have checked solder connections, in fact re-soldered them all. Still no better. I am thinking of opening up the pot and clean it, I have never done it before, should I attempt to open the pot and clean it ?

 

[OMGCat!]

That's an odd failure but sounds like you've found it.
Does it clean up at any point in the sweep of the volume or balance control?
Most times you will have a faulty spot on the track but if the wiper failed it could also cause your problem.

Next I would use a multimeter on each pot to find exactly which is bad. I'm guessing you'll likely have odd resistance readings compared to spec and/or the properly working channel.

I've never attempted to disassemble a pot but I've seen it done here and on YouTube videos.

 

[sajjad amer]

It was a silly mistake on my part.I de-soldered the pot and when looked under magnifier saw solder in it, probably it happened when priming the solder pump!!
I managed to blow it out with compressed air and it is working again.
Thank you once again, to everyone for help.

 

[OMGCat!]

Nice work!