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KLH R3100 stereo receiver volume won't adjust

bbullsj

Nov 28, 2018
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Only way I could get it to work is to open the picture and take a Snip of it.
 

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bbullsj

Nov 28, 2018
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Here are some more.
 

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Tha fios agaibh

Aug 11, 2014
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The two encoder channels end on the left two nodes out of 5 (solder lumps).

What's directly on the other side of the board?
Screenshot_2018-12-10-19-56-52-1.png
 

Tha fios agaibh

Aug 11, 2014
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Looks like the microcontroller read/write pins 16 and 17.
What's on the other side of here near the vol encoder?
Screenshot_2018-12-15-17-38-24-1.png
 

Tha fios agaibh

Aug 11, 2014
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No help there.
I'd be looking at opamp 4558 which I think is thisScreenshot_2018-12-18-21-14-46-1.png 8 pin component.

Check power on pins 4(+) and 8 (gnd).
Outputs pins 1 and 7, can be checked with an audio probe or amplified speaker with an isolator cap of about .1uf. (Google audio probe) The input can be checked similarly with an audio input fed to the receiver.

One input side is pin 2 (neg)and 3(pos) and the other input is 5,6, The signal input (whether neg or pos) depends on circuit design.
Try googling testing op-amps
 
Last edited:

Ylli

Jun 19, 2018
411
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Jun 19, 2018
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Do we have a schematic on this one? The 4558 is commonly used as the DC servo - making sure the outputs are centered at 0 volts.
 

Ylli

Jun 19, 2018
411
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Jun 19, 2018
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411
Schematic of the KLH R3100, not the op-amp.
 

bbullsj

Nov 28, 2018
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Nov 28, 2018
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Looks like a little more time than I want to spend in fixing it and have too much going on at the moment. Is it work anything to anybody in parts?
 

Tha fios agaibh

Aug 11, 2014
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Joined
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Looks like a little more time than I want to spend in fixing it and have too much going on at the moment. Is it work anything to anybody in parts?
Perhaps someone local.
I like to post ads on craigslist or freecycle that say "free for parts or repair" Usually it's gone within a few hours.

It's nice to see things get recycled/reused rather than going to the landfill.
 
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