View Single Post
  #1   Report Post  
Posted to sci.electronics.repair
n cook n cook is offline
external usenet poster
 
Posts: 1,220
Default Tip: Renovating pot with push-pull switch.

Due to hardened lubricant on the flimsy slide switch contacts
If anyone happens to know a generic name or name of the manufacturer?
http://home.graffiti.net/diverse:gra...et/pot-sw2.jpg
Has a positive feel going in and out, so more than just a slide switch.
Logo? is a Studebaker type logo "lazy S" in a circle, M in a circle and then
FE
also use of J without a top bar as eJ

If I was doing it again I'd feed a wire through the point marked ""
over the boss "B" that connects with the axial shaft of the pot , and twist
over the body to keep the boss from moving and dislodging the spring, (maybe
, I would not be too sure, the other end would not lift, before you can
restrain it).
(You have to dismantle the switch if you need to renovate the pot)

And no need to bend down the rear closure of the housing
http://home.graffiti.net/diverse:gra...et/pot-sw1.jpg
1 mm squares on graph paper
Didn't loose the spring but just in case dimensions are 0.55mm wire, 9mm
arms inc ring , ends 9 mm apart, 2 turns minus angle between arms and 3.3mm
o/d of
ring.
At mid position , maximum spring force , so not stable position marked
between the and
http://home.graffiti.net/diverse:gra...et/pot-sw3.jpg
The flattish section with 2 nibs goes opposite the boss part of the other
section.
Hold together enough to add a small dot of hot-melt glue on each corner on
the surface that slides in the housing, there is a bit of space there.
Position the 2 parts as in the knob pulled out posistion , before gluing and
check that it will go in the housing and over the pot shaft end.
Now for the spring.
Place the glued parts in an engineers cramp or similar to give some more
temporary closing force, and easier to hold.
Push spring, ring first, in through the side with the narrow slot leaving
the arms outside enough to grab one , to force into the slot in the flattish
PTFE part.
Push both arms in , restrained by finger fleash in the larger hole of the
other side.
With a needle point or similar, through the narrow slot, force the other
tail/arm into its slot.
Remove the cramp carefully , in case the hotmelt is not suifficient, and
loose the spring.
Replace in the housing and wire down as described earlier , just in case the
glue spots fail before finitshing off the slide switch refixing.

Reminds me, when repairing some kit in a lab with some very large pieces of
materials testing kit around, dynamometers etc. I was taking something apart
to repair and some very complex shaped spring flew out.
I requested the cleaners not to clean the floors etc that night , so could
resume the hunt next day. Could not find it. Went to use the 500 ton
dynamometer test set and the spring was in front of my face at eye hight
lodged in one of the 1 inch diameter recessed Allen head bolt holes for the
Amsler control pannel housing.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/