Curt Palme CRT Tech
Joined: 08 Mar 2006 Posts: 24396 Location: Langley, BC
TV/Projector: All of them!
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| Posted: Sun May 15, 2011 6:27 pm Post subject: Helpful receiver repairing tip # 1 |
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thought I'd share this since I've seen a lot of it.
Many newish (15 years and newer) receivers and mini stereos use stepped volume controls instead of a variable resistor like the older sets do. By 'stepped' I mean it's simply an on/off switch, which sends a series of pulses to the CPU that turns the volume control up and down on the receiver (Mac can chime in if I've described it incorrectly).
I've seen a bunch of these sets now (Pioneer, Sony, etc) where the volume level will do strange things when you crank the control. NO change in volume, volume up works but not down, massive jumps in volume suddenly, etc.
The problem is always the same, the control/switch contacts are erratic. Fortunately it's a very easy fix (but you do need to know how to solder).
Remove the control from the front panel. you'll see that it's square, and the front of the control is held to the back via a thin piece of formed metal with 4 little tabs bent at a 90 degree angle which holds the unit together. Use a small screwdriver to bend open the tabs, and pull the control apart. I use Caig contact cleaner on a Q tip to clean the wipers and the round disc where they contact. The Pioneer I just looked at had significant wear on the gold plating where the wipers contacted the stationary disc, so I very slightly moved the wiper contacts so they hit virgin gold. A tiny shot of Caig onto the tiny PC board, and I reassembled. Perfect operation for another 10 years!
Put the control back in, and you're good to go. It usually is harder taking the control out of the set compared to cleaning it.
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