'303 env mod pot - thanks

[Rob Zero]

----- Original Message -----
From: Trevor Page <trevor at resonance.fsnet.co.uk>
To: <synth-diy at node12b53.a2000.nl>
Sent: Saturday, April 22, 2000 11:21 AM
Subject: Re: '303 env mod pot - thanks


> 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).

Well, if that doesnt work, try covering it with clear epoxy instead of the
acrylic.. that epoxy gets hard as hell! ;)

Rob

>
> 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
>
>