[sdiy] Serge Pots WAS: Starting my next major project...

[Peter Grenader]

on 6/26/02 10:42 AM, Grant Richter at grichter at asapnet.net wrote:

> This is how Serge built his early modules. He used nylon bushings at the
> front to remove the wobble from the long shafts

Not at first he didn't! I worked there when they discovered those things. At
first they just came straight to the faceplate with no support, the 1/8 inch
pots shafts would just float through the 1/4 holes on the metal facelplate..
The dials would wobble all over the place.  If you gently wiggled a dial
from side to side, every pot in the module would move with it.

BTW, if anyone needs those nylon spacers Serge later used to support the
pots shafts through the faceplate clearence hole, there are zillions of them
at All Electronics.  They may not be listed in their catalog, just call
them.  Thay are about an inch and a half long.  They also have a bulk of
those long shafted pots - don't remember which value.

While fixing one problem (wiggling pots), these spacers created others.  If
the PCBA wasn't exactly aligned to the faceplate, it would cause the pots
shafts to rub against the ID of the spacers and the pots would feel very
stiff.  It seems like a no brainer to locate the PCBAs correctly at first,
but when you're dealing with a rack with 10 or so modules in it, tolarances
tend to build up and it gets tricky down the line.

On a further note, Serge started replacing these long shafted pots in his
second series of designs (NTO, the varible Q new filters, the panner, the
TBK, etc) with Allen Bradley faceplate mounted sealed pots.  They were
tauted to be the end-all to the problem - but in reality they were complete
shit (read: they were about as sealed as my butt).  In a matter of months
they would get all dirty inside and the only way to clear it out was to
(very carefully) drill two  holes in the base of the pots just large enough
to get the straw from a can of WD40 in there to skwirt the crap out the
other hole you drilled.  Major pain.  If you drilled a the wrong place,  you
were off to the electronics shack to buy a new pot. An what happens when you
spray that stuff in the pot?  It becomes a dust magnet and you found
yourself having to repeat thee nitre process in a regular basis.

Another annoying problem with Serge stuff at the time is he used these
banana jacks that didn't screw in, they had this toothed lockring that you
would pressfit  flush to the back of the faceplate when you installed the
jack, It would bite into the plastic wall of the jack and would be held on
under that tension - permanently.  God forbid something happen to the jack
down the line which required you replace it, because it was a mess,
especially because he was using paper faceplates at the time, that really
wanted to delaminate around the holes.  Pulling those jacks would surely do
this when you lifted it out once you got the lockring to let go.

This is why I chuckle at some of the comments about the lousy mini jacks on
Doepfer/Analogue Solutions and Analoguye Systems' gear.  This can be fixed
in about a microsecond by simply pulling the module and pressing the tip
contact in a little bit.  At least you don't have to get out a drill!!!

- P