RE: WG6100 Question - Ongoing

The socket that the screw goes into has protrusions that go into the holes
in the chasis. The screw is a lot smaller than the hole and as long as the
protrusions (can think of a better name) are in the holes, it keeps the
screws away from the chasis. If the socket isn't seated (or the protrusions
are broken off) the transistor assembly can move around and the screws can
touch the chasis, which will cause a short. (the chasis is ground and the
case of the transistors are either +27, or -27.

-jeff

> -----Original Message-----
> From: Dennis Shirk [SMTP:dshirk@godfrey.com]
> Sent: Wednesday, March 17, 1999 8:20 PM
> To: vectorlist@mcfeeley.cc.utexas.edu
> Subject: Re: WG6100 Question - Ongoing
>
> Thanks for the tip, but if you could supply a clarification...
>
> The TO-3 socket is on the OTHER side of the chasis. The screw holes in the
> chases are just plain drilled holes, no special insulation, so the screw
> has
> to pass through the TO-3, through the chases, and THEN into the TO-3
> socket.
> I can't imaging how the screws could NOT touch the chasis.
>
> How is it that where the screw passes through the chasis, that it does not
> short out?
>
> Sorry if this sounds like a stupid question, I am just trying to minimize
> the amount of components I need to replace the next time I fire this thing
> up and parts go up in smoke.
>
> Dennis
> http://gameroom.godfrey.com
>
>
> -----Original Message-----
> From: Clay Cowgill <ClayC@diamondmm.com>
> To: 'vectorlist@mcfeeley.cc.utexas.edu'
> <vectorlist@mcfeeley.cc.utexas.edu>
> Date: Wednesday, March 17, 1999 7:23 PM
> Subject: RE: WG6100 Question - Ongoing
>
>
> >
> >> Between the transistor and the metal monitor panel, there is now a
> >> thin
> >> layer of heat sinc goo and the thin piece of plastic. What is keeping
> >> the
> >> screws that connect the transistor to the wires on the other side from
> >> shorting on the metal monitor panel, or does it matter??
> >>
> >The Plastic is actually Mica -- used as a high-temperature insulator
> >between the TO-3 case and the monitor chassis.
> >
> >> Some thin plastic bushings came with the new transistors, should they
> >> be
> >> used, or does the transistor NEED to ground (via the screws) on the
> >> metal
> >> monitor panel?
> >>
> >If I recall correctly, the screws actually touch the TO-3 case (which is
> >insulated from the chassis by that mica insulator) and then screw into
> >the insulated TO-3 socket. So, no-- the screws shouldn't give a path of
> >conduction to the chassis. If your TO-3 sockets are in good shape you
> >probably don't need the nylon bushings, but double check that the TO-3
> >cases don't ohm out to zero against the chassis. (Probably not a bad
> >idea to replace the Mica insulators-- and use plenty of heat sink
> >compound...)
> >
> >-Clay
Received on Wed Mar 17 21:45:50 1999