[sdiy] TB-303 servicing questions

Robin Whittle rw at firstpr.com.au
Tue Dec 3 11:41:43 CET 2013


Hi Damien,

I don't have any great insights into silicone grease.  I am using some
light grease I bought many years ago, with a brand name which no longer
exists.  I only use about 1 cubic millimetre - on the friction ring and
around the shaft itself.  I clean the old grease off with tissues,
probably leaving a little behind, but that's OK.

I don't lubricate the tracks or wipers - but there is a whole range of
products called DeoxIt, some of which may be intended for this.

The 3rd and 4th photo here and the text make it very clear what the
cutting problem is with the original ALPS pots:

   http://www.firstpr.com.au/rwi/dfish/pot-wear/

The same thing could happen with the Bass Bot 6 small pots and those
being sold by Technology Transplant - so don't press down on them while
turning them.  I have a modification which is quite tricky.  I dismantle
the pot, make a slight countersink hole in the rear of the phenolic
panel, and then make a special dimple in the back piece of metal to be a
tiny fraction of a millimetre higher, going into the now countersunk
hole.  When done the right way (I spent half a day making a tool, and
use a micrometer to get it right, filing it down if I need to) this
reduces wobble in the shaft and prevents it being pushed down enough to
cut the tracks.  This description will only make sense if you have a
dismantled pot in front of you.

I got the two sets of pots from Technology Transplant about two months
ago.  They are still for sale here:

   http://www.technologytransplant.com/index.php?cPath=30_29_10

Cy, previously of Technology Transplant, runs Cyclone Analogic and from
all I know is no longer associated with Technology Transplant.

  - Robin




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