Re: Holy S*%T WTF did I just do to my game!?! STTNG--- UPDATE

Thanks Martin, Clay, and Lloyd... doing all of this right now.

Just did the switch test per Clay's guide... all seems fine. Has to be
under the playfield right?

Have new set of trough boards, I'm putting them in. Opto is out right
now. Anything else I should look for there? The only LM339 on it is a
U5... not sure if that should be an issue, but it's the only one not
replaced.

On May 29, 7:07 pm, martin <martin.reyno...@xxxxxxxxx> wrote:
On May 29, 4:51 pm, c...@xxxxxxxxxxx wrote:





1. Put the original CPU board back in your game.
if you're gonna do board swaps, you're better off
going in "the other direction". that is, put the questionable
CPU board in the T2, instead of the good CPU in the STNG.
that rule doesn't apply all the time, but in the case of WPC
CPU boards, i think it's a better approach.

2. boot game, put it in T1 switch test. remove all the lower
connectors on the CPU board only. use two alligator
clips and a 1n4004 diode. like the WPC repair document
says, test the row/columns. this will tell you if the switch
problems are in the CPU or the playfield.

I'm gonna assume the CPU board is Ok, and
that the problems lie in the playfield.

3. reattach all CPU board plugs. REMOVE all
plugs going to the under-playfield opto board.
test all the playfield switch (non-opto) and see
what works or doesn't, and if the short is still
there. If the short is still present, you have a
genuine short!  Like are real short. the game is
telling you which wires (columns/rows). trace
them through the playfield. use the manual and
go thru all the switches in that row/column, and
trace the actual wires looking for shorts.

4. if the short goes away when the under-PF opto
board is disconnected, then the problem is
obviously in the opto board!  Personally i would
socket and replace all the LM339 chips. but
also look for stupid stuff. Like a solder drip
on the board connector pins (both sides of
the board). or IDC opto board connector
problems (pretty common for that era of game).

report back.

On May 29, 7:30 pm, djcharli...@xxxxxxxxxxx wrote:

Hey there helpful RGPers... Martin, Korn, Lloyd, and a few others will
remember this.

http://groups.google.com/group/rec.games.pinball/browse_thread/thread....

In any case, here is the progress:

Chips arrived today... I installed new LM339's at U3, and U4 on the
opto board. Instead of attacking the CPU issues, I swapped the CPU
with my T2 CPU. Changed chips, it boots, and I get the same "Ground
short row 6" error I had with the STTNG CPU. I change LM339's at U1
and U2 on the opto board, check, same error... none of the opto
switches are working. Most regular switches are, but not all...
flippers are not working.

The opto board LED is not lit... I checked it with a modded 12v
computer power supply (per Clay's manual) and it does light there
(just to make sure LED worked). I checked all the fuses, and they are
all good.

I'm going to replace LM339 on the trough next (the LED there is lit),
then go with Clay's matrix / diode on a clip test.

For the record, I checked all traces and plated thru holes on the opto
board for continuity before and after the new chips were installed.

Any more suggestions from the brigher than me guys in the crowd? Am I
overlooking something silly?

Thanks guys.- Hide quoted text -

- Show quoted text -

On top of Clay's fine advice, I would suggest disconnecting the opto
board AND the trough board first. See if that fixes the CPU ground
short. If it does, you have opto and/or trough problems remaining. It
is very likely that you also blew the trough opto board.

You may also have shorted diodes on these boards.

On your original WPC CPU, replacing the ULN2803 (and socketing it)
will probably fix it.- Hide quoted text -

- Show quoted text -

.

Relevant Pages

  • Re: Holy S*%T WTF did I just do to my game!?! STTNG--- UPDATE
    ... Just did the switch test per Clay's guide... ... CPU board in the T2, instead of the good CPU in the STNG. ... problems are in the CPU or the playfield. ... plugs going to the under-playfield opto board. ...
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