Re: Rebuilding a System 9 Power Supply


It is a Space Shuttle.  In game mode neither the left saucer or the T
target function.  I haven't tried in test yet since I think it should
work fine in game mode.  The switches are recognized though if I
manually reset the T target and drop it.  If I fire the T drop target
manually it has plenty of power to reset so at least I don't have a
mechanical problem.

Hugh- >

Sounds like maybe a grouding problem.
Make sure you have enough screws holding the MPU board and power
supply boards to the back ground plane. Check for missing grounding
straps. Check for loose connectors from the transistors to the
solenoids

Check transistors Q49 and Q39 for operation of the coils. (Ground
their tabs also to check the wiring to the coil) If these coils fire
by grounding the tabs odds are it's a transistor or earlier problem on
the board). Fix these transistors before the fuse problem.

For the fusing also check the power resistor circuit boards for the
flash lamps and make sure none of the 330 ohm resistors have been
swapped with anything with a much smaller resistance. This resistor is
always "ON" to keep the bulb filament warm. I believe the othe
resistor should be 7 ohms and that one is only "ON" when the
transistor fires.


BTW I have seen GI burn all types of connectors, in all different
spots, including the AC lines coming into the board on later system
11's off board connectors. I have always replaced the burned items to
match the original configurations and have only had one issue return
with the game in Home Use (that was a system 7 and it was the typical
4 GI lines IN/OUT pins connector.) WMS changed the designs on the GI
over a dozen times, but IMHO they never got it right and never fixed
it even right up to the end.

.

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