Jerry,
Now you mention it .........
My recollection of the sequence of events was that the Notch pot was a
bit "scratchy" but operated over its full travel. Whilst I had
everything apart for the DDS modification I decided to to take a look at
the pot. I remember spraying some switch cleaner into the rear gang -
the only one I could really get access to. It was after that it failed
completely apart from about the first 30 degrees of travel.
I pulled the pot off the board and disassembled it - right back to the
track. The front gang was fine, but the rear gang looked like the
carbon(?) had been completed stripped from the substrate. There were
thick black deposits on the slider that looked like they might once have
been the track. Probing around the substrate with an ohmmeter, it
looked like pure insulator.
When I tell it like that, it sounds obvious what must have happened!
I can't see anything on the switch cleaner can that indicates what the
liquid is.
I'm expecting the replacement pot mid-week and will let you know how it
goes. From the Maplin drawings it looks like the front-to-back pin
spacing between gangs is correct, but I may need to spread the pins
sideways slightly to fit the PCB holes.
73,
Steve G3TXQ
On 08/02/2011 05:35, Dr. Gerald N. Johnson wrote:
Cramolin does not recommend DeoxIT for pots. It might dissolve the
carbon track, but they do make a product designed for pots.
Steve found a pot at Maplin with it looks like the perfect specs to fit,
needing only that the shaft length be trimmed to fit. I'm thinking of
ordering some to have for spares in my Corsair II. Might be slow on
delivery once I convince them my order is real.
73, Jerry, K0CQ
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