'303 env mod pot - thanks

[Trevor Page]

Hi list,

Many thanks to all who offered advice on the '303 env pot problem. I got on
the blower today to Maplins and ordered a bottle of conductive silver paint,
together with some acrylic pcb protector stuff which I will apply over the
paint to protect it (not sure if it will be sufficient though).

Theo suggested:

> Just silly me asking, but what is so special about the env mod pot in the
> 303???
> 50K lin is a standard value. Physical dimentions can't be a real problem
> either.
> If the shape of the pot is a problem for you, please let me know how it
> should look.
> Have plenty of choice here.

Actually the env mod pot is 1Mohm, rather than 50K as incorrectly stated in
the service manual. Of course, there's plenty of 1M pots available. However,
physical dimensions are certainly a problem. There does not appear to be a
replacement available that has the same length of shaft as the pot used in
the tb303. If you use a different type of pot, you have to hack it in
somehow. There's no pot available that will fit straight in. The fact that
the pot is only mounted to the pcb, and not bolted to the chassis, is a bit
of a pain.

colin f. said:

> In what way is the pot unrepairable ?
> If the track is intact and it has just lost it's contact with the pins, a
> bit of silver conductive paint can fix it.
> I've repaired some 303/606 pots that were in a very bad way...

The three tracks have worn where the outer edge of the plastic rotating part
touches the little pcb. The three tracks leading form the carbon track have
been neatly spliced about 1mm out from the carbon track itself. This
happened because the plastic part had split slightly at one place, which
caused a nasty sharp edge to rub against the tracks.... bah..

Cheers,

Trev