Harmon Kardon hk570i Stereo receiver only plays on one side - grounding issue?

[TJPennypacker]

Hi folks. I’ll try to explain my problem as clearly as I can. Any suggestions will be much appreciated.
I have a Harmon Kardon hk570i stereo receiver and sometimes it will play through both speakers, but often it will only play through one side. What seems to fix the problem (temporarily) is disconnecting and reattaching the ground wire from the phono turntable to the ground post on the receiver. While this usually gets the both speakers working, they will operate at a different volume, then over time, one speaker will cut out again. I wonder if this is a power issue, a grounding issue, or a problem with a component in the receiver.

Both speakers work properly and the problem occurs on the radio function and the phono function but does not seem to be a problem with the aux function.

Any ideas?

 

[Martaine2005]

Hi, I would be looking for a loose/bad connection on the faulty channel first.

Then a closer inspection of the faulty channel. Dry/cracked solder joints and possibly leaking or swollen electrolytic capacitors.
Confusing why it works on AUX though.
You’ll probably be better off looking for a schematic and posting it here.

Martin

 

[H2814D]

Hi folks. I’ll try to explain my problem as clearly as I can. Any suggestions will be much appreciated.
I have a Harmon Kardon hk570i stereo receiver and sometimes it will play through both speakers, but often it will only play through one side. What seems to fix the problem (temporarily) is disconnecting and reattaching the ground wire from the phono turntable to the ground post on the receiver. While this usually gets the both speakers working, they will operate at a different volume, then over time, one speaker will cut out again. I wonder if this is a power issue, a grounding issue, or a problem with a component in the receiver.

Both speakers work properly and the problem occurs on the radio function and the phono function but does not seem to be a problem with the aux function.

Any ideas?

That receiver is probably 40 or more years old. Based on your description of the problem, the most likely cause(s) are due to failed/failing capacitors. You will have to open it up and do a visual check first, if you know what you are looking for, and then do some component replacement more than likely. Or you can try and take detailed and clear photos of the components on the circuit boards and post them here for review. Both the front and back sides of the boards, if you want to go that far. Sometimes the problem components are obvious, but I wouldn't continue to operate the receiver until you find out what is causing the problem otherwise you may end up damaging harder to diagnose components.

Note that that receiver has a wire driven channel display and tuner, which will necessitate you pay close attention to a lot of things if you decide to take it apart.

 

[Delta Prime]

What made you decide to start pulling wires and switching what you think is ground?
(Rhetorical question)
You're more than likely cause more damage than the symptoms you described while pursuing your curiosity. Therefore I shall add to you being mischievous on a different level; here's the schematic for your unit along with component placement, component bill of materials.
Page 5 Speaker System 1, Left channel
Right channel, DC voltage balance adjustment.
Follow the procedure...