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Super mysterious volume pot issue

Garret86

Garret86

Member
I’m having an issue with a volume pot where where it only works when I hold the knob at a specific angle. When I let go of the knob the left channel plays at a random volume , and the right channel plays at where ever the knob is set. When I jiggle the knob and hold it both channels sync up in volume. Have tried cleaning it extensively and does not seem to be a corrosion issue. The audio also distorts if I wiggle the pot or knob. Any ideas on what I can do next?
This is on a vintage ROTEL rx-603
 
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yeah, agree with that. Busted solder joint or its falling apart internally and holding it just so makes contact again. Most volume pots have a resistance track with a terminal riveted to it. I've had those rivets come loose, and I've had the board where the resistance track lives crack so it makes intermittent contact. Hopefully its just solder since practically speaking thats the only one you can fix. If the pot itself is bad, you fix it with a replacement pot.
 
gadget73 said:
yeah, agree with that. Busted solder joint or its falling apart internally and holding it just so makes contact again. Most volume pots have a resistance track with a terminal riveted to it. I've had those rivets come loose, and I've had the board where the resistance track lives crack so it makes intermittent contact. Hopefully its just solder since practically speaking thats the only one you can fix. If the pot itself is bad, you fix it with a replacement pot.
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How do I desolder the pot off the board for inspection?
 
Sounds like the pot knob took a hit. Sometimes you can to a visual and see if the pot. solder leads move. might be best is to just reflow the pot. solder joints and test again. You can solder right? to desolder you need a solder sucker or use solder braid and flux helps. there is nut holding the pot. to the chassis.
should be a exploded view the service manual.
https://www.hifiengine.com/manual_library/rotel/rx-603.shtml
 
Binkman said:
Sounds like the pot knob took a hit. Sometimes you can to a visual and see if the pot. solder leads move. might be best is to just reflow the pot. solder joints and test again. You can solder right? to desolder you need a solder sucker or use solder braid and flux helps. there is nut holding the pot. to the chassis.
should be a exploded view the service manual.
https://www.hifiengine.com/manual_library/rotel/rx-603.shtml
Click to expand...
How can I go about reflowing , I have minimal experience. How do I know what to reflow , is it the stuff on the underside of the board beneath the pot , it looks like the pot has little metal feet that attach it to the board.
 
Garret86 said:
How can I go about reflowing , I have minimal experience. How do I know what to reflow , is it the stuff on the underside of the board beneath the pot , it looks like the pot has little metal feet that attach it to the board.
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Do a Google search on the term cracked defective solder joints and select Images. Basically you'll see a dark ring around a broken joint, and if you wiggle the volume pot you should see the joints flex.
 
Ray Gianelli said:
Do a Google search on the term cracked defective solder joints and select Images. Basically you'll see a dark ring around a broken joint, and if you wiggle the volume pot you should see the joints flex.
Click to expand...
This is the area under the volume pot, is this what I should reflow ?
 

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That's it. Just reflow where the pins of the volume pot stick into the board itself. I am hoping that this is the problem otherwise the volume pot itself is bad.
 
excellent. Bad solder at things that can be moved from the outside is probably the single biggest "does odd things" problem I've run into. Car audio amps with busted solder on the input jacks are extremely common, but anything where the part isn't super physically secure and can cause the joint to be stressed until the solder cracks can have this happen.
 
gadget73 said:
excellent. Bad solder at things that can be moved from the outside is probably the single biggest "does odd things" problem I've run into. Car audio amps with busted solder on the input jacks are extremely common, but anything where the part isn't super physically secure and can cause the joint to be stressed until the solder cracks can have this happen.
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Agreed that mechanical movement causes issues like cracked solder joints.

Our home phone had intermittent issues with the receiver cord as my wife used to stretch it when using. Since we really liked the phone, I opened it and reflowed the solder joints between the headphone jack and board. Phone worked for many years after that.
 
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