The two nylon "washers" (isolation washer/bushing/spacer) are used where the
bolt goes through the L-bracket and then through the transistor tab where it's
held in place with a washer and nut. They are used to isolate the transistors
from the L-bracket.
Note that you should also have a piece of mica separating each transistor from
the L-bracket on the component side of the L-bracket. You can use heat sink
compound here similar to the larger PITA TO-3 case transistor (pain to remove
that one).
Watch out when removing the larger power transistor that it doesn't screw up the
nylon isolation spacer that goes through the L-bracket where the two screws hold
it in place.
You can put heat sink grease on both sides of the mica isolator. Just smear a
very small amount to reduce air gaps on both sides of the mica, then press the
mica in place.
The nylon isolation bushing (or washer) has a larger round side to it. That side
is on the L-bracket metal side rather than on the transistor side. just push the
screw through the isolation washer (larger side, you'll know what I mean when
you see it) then put the screw with the isolation spacer through the L-bracket
making sure the isolation nylon goes through the screw hole in the L-bracket,
then through the transistor (with the mica insulator between the transistor and
the L-bracket), and then use the lock washer and nut to tighten it up. Since the
screw is passing through the isolation washer and is completely isolated from
the L-bracket, it can't short against the L-bracket. Remember that the wider
diameter end of the nylon isolation washer is towards the head of the screw, not
toward the transistor.
If you don't have the mica insulator on the bottom transistor between the
L-bracket metal and the back of the transistor, when you attempt to plug the
display cables in and turn the game on, it will blow the 60 volt fuse.
Ed at GPE sells a TO-3 style heat sink gasket (number Product ID: HF115TAAC-05)
which can be found at
http://www.greatplainselectronics.com/products.asp?cat=28&pg=2. Note that you
will also find the mica insulators on this page as well. While there, why not
order some stand-offs while you're at it since these things are often busted on
a system 1 game (or others for that matter).
He also sells the TO-3 transistor spacer (Product ID: Product ID: 18PTI1HDWOB)
which is shown at
http://www.greatplainselectronics.com/proddetail.asp?prod=18PTI1HDWOB. This is
the part that can get broken when attempting to remove the TO-3 larger 2-screw
transistor (soldered from the component side of the circuit board - grrrr).
Depending on which pin contacts metal on the TO-3 transistor, the voltage
regulator (op-amp) will get quite hot and possibly damaged. This is usually the
tip-off that your TO-3 style transistor has a pin contacting the L-frame bracket
due to a broken or missing isolation spacer.
this should answer your question. I've rebuilt numerous System 1 power supplies
and they seem to hold up quite well. Ed at GPE also sells a System 1 power
supply replacement if you want a new one. You can see his power supply at
http://www.greatplainselectronics.com/proddetail.asp?prod=125%2D101.
stevebo
Post by t***@yahoo.comI have made a dumb newbie mistake by taking the Gottlieb System 1
power
board apart and not looking where every part came from. Actually,
these 2 synthetic washers fell out as I was separating the board from
the "L" bracket. I believe they came off of the bolts that hold the
TIP31's to the L bracket, but I am not sure which way they go. Does
anyone know if these washers go on the board side or the L side? Is
their function to isolate the TIP31 from the L bracket? There is a
heat sink there.
Thanks,
R