Hello world, this time I'm gonna share my experience in fader repairs and restorations in last few years:
Sony Precise V3 high fidelity audio set (1984). A worth restoring unit.
Disassemble of this well finished ancient units is easy (here TA-V3 Integrated Stereo Amplifier 2x33W THD0.09%, part of audio set 'Syscon 352' aka 'Precise V3'), finding its 'service manual' also will be helpful (or a similar model one).
You'll
need to release the back of the front panel, which contains the
control tone and volume section as you can see in the picture.
Internal parts of TA-V3 amplifier with robust metallic faders / slide pots of the front panel unassembled.
In
this situation, you have to unweld the defective faders (use abundant
welding paste and desoldering wick; while a desoldering pump is an optional help, I managed well enough only with the wick) and open them.
As usual, before the
above you could try cleaning the fader tracks from the exterior avoiding
the unwelding tasks but, when it doesn't work, I highly recommend to unweld and
unassembly them completely to achieve a full repair and cleaning, the results can be surprising.
A control tone fader (double/stereo 100kOhm sliding potentiometer) disassembled. Here you can see the copper and carbon tracks side-by-side on the left part, and the sliding contact skates/brushes fixed to the plastic moving head on the right.
At this point, the shown causes of the fader malfunction can be diverse:
CAUSE: Dust or dirt in the carbon and copper tracks - CLEAN with isopropyl alcohol or some zero residue contact cleaner (Lubrilimp, CRC, Deoxit, etc.).
If you have at home, could also use first some minimum residue (oil/grease) contact cleaner, in order to drag dirt and lubricate a little the moving parts of the fader. But this kind of faders works better without grease o with very little quantity of it. You could lubricate only the plastic or metallic moving parts with silicone grease, but it's preferable not to lubricate the contacts, carbon tracks nor sliding skates/brushes.CAUSE: Sliding contact brushes bent or loose - STRAIGHTEN and/or GLUE IT to the sliding plastic head. An effective gluing could be achieved with the soldering iron tip by fusing a little the plastic part to the metallic brush, very carefully.
CAUSE: Broken or worn out carbon tracks (check with continuity tester) - no possible repair as far as I know - REPLACE with similar spare part.
I hope this info can be helpful to someone... tell me you experience and/or any suggestions!
