Tech: Williams System 6 - stuck in audit mode
Sprout
After digging through older posts and covering everything that's
worked for others, I'm still unable to resolve issues with a board I'm
repairing for a friend.
What I see - depending upon the position of the toggle in coin door
(up/down), I get power/no displays, or I get the game coming up in
audit mode, and very quickly scrolling through the audits in the coin/
credit display, with the respective values showing up in the player 1
display.
If I open the coin door, and flip the power off/on very quickly, the
game comes up for perhaps 3/4 of a second before going right back into
the same audit mode noted above.
Also - if I drop Leon's test ROM in - no issues found - PIA checks
out, LED's cycle as expected, and memory tests pass as well.
Issues isolated to the MPU board - can drop my own board in (both
Gorgar boards) and have zero issues. Migrating all ROM's, PIA, CPU,
and 5101 between boards, as well as one socketed 6810 - all his chips
work fine on my board, and my chips do not resolve the issues on his
board.
Issues first appeared after he "fixed" the board (for what I insisted
were interconnect issues) by replacing all the ROM sockets. I've
repaired some hacked traces, ohm'ed everything out - sockets are solid
and no shorts after quadruple-checking them. Same done with the 5101
socket (which I installed after thinking it was a 5101 issue).
Sockets tested by putting one on the pin of the respective chip, and
the other on the respective socket pin on the bottom. Traces verified
in a similar fashion - I'm confident that they're ruled out.
I've since replaced the blocking diode at D17, as well as IC5 (74LS02)
- same issues.
I'm stumped - any suggestions appreciated!
Retrogameconnection
Sorry if this is painfully obvious but you didn't mention it....
What is the status of the battery holder? Have you replaced it with a
new one? Can you measure the battery voltage at the 5101?
Sprout
Sorry - currently no battery holder installed; it was mounted off-
board, and I disconnected it while I was addressing the other issues.
If I reconnect it, symptoms pretty much the same, although it does
occasionally seem to try to stay out of audit mode - it displays the
default high score, the "high score to date" lamps light on the head
door, coin door lockout engages, and it hangs there. Most of the time
however, the symptoms are the same. I've always been able to do the
quick double-switch of the power to get these boards to come up
without batteries in the past, so generally don't have batteries
installed during testing - it is odd that the symptoms are somewhat
different with them present though.
If the switch is in auto, the symptoms are as described above (scrolls
through audits at either normal, or sometimes very high speed). If
it's set to manual, I usually get blank displays.
Voltage on TP 7 & pin 22 of the 5101, and banded side of D17 is
~4.3v. Non-banded side of D17 is ~4.7v.
Marvin's seems to point towards IC's 10, 12, or 27 next. I checked
pins 9-16 on the 5101 when the game seemed hung at the high score area
as noted above, and they were all pulsing so I figured that probably
means that IC10 is ok.
Perhaps the core issue really isn't audit-related; just the game
resetting back into audits, or simply hanging right out of audits?
Retrogameconnection
>
> - Show quoted text -
If it's scrolling through all of the audit items then I would guess
that the diagnostic switch on the coin door is stuck closed (or a
broken/bad diode on that switch). Whether the auto up/down is up or
down it should not be scrolling through the audits unless the advance
button is held down. You could test the switch continuity with a DMM.
Have you tried disconnecting one wire from the diagnostic switch to
see if the scrolling stops? I bet the CPU is ALWAYS getting the signal
from the switch to go into audit mode so it is unable enter into
"attract" mode. You could also try disconnecting the entire coin door
and then quickly turning off and back on again to see if you can get
into attract mode that way.
Good Luck.
HTH.
Sprout
Definitely not the coin door wiring; I'm testing his Gorgar board in
my Gorgar cabinet, and I have no issues with my board when it's in the
cab. The board certainly *thinks* I'm holding down the button. I can
press the start button while it's scrolling through the audits and see
values change. If I set the switch to "manual", I can move through
the audits and make changes there as well. Very strange, and not the
typical "stuck in audit" type of issue that I've dealt with in the
past.
Worst-case, I suspect I'll be looking at IC's 12 or 27 next, but was
hoping somebody had come across this previously, so I could avoid
shotgunning parts.
Thanks!
me
I had a similar issue. It ended up being the roms were screwed up.
Burned a fresh set and everything was fine. When the Gorgar boards
are swapped, are you using the same roms. Or do they each have their
own roms in. Try the roms from the working one. Either that or those
damn Scanbe sockets.
me
I just found the first post to this string that mentions what I was
talking about. Nevermind
firepower
Interesting problem. Leon's chip doesn't care about the coin door
switches, it only uses the CPU diag switch to start the memory test.
Had a look at schematics and the coin door wiring for those switches.
Here's what to do:
Don't disconnect the coin door or connector at 1J4 on the MPU board.
Open coin door.
Set the (up/down) switch to manua/down. Then measure the voltages at
pins 1-4 on 1J4. Here's what you should see:
Pin 1 = +5v or so. Closing the coin door will ground this to 0v. (Mem
Protect Interlock)
Pin 2 = Ground. Should never change. (Diagnotic Switches common)
Pin 3 = +5v or so. Pressing Advance will ground this to 0v. (Advance
sense)
Pin 4 = +5v or so. Toggle switch to Auto/up will ground this to 0v.
(Auto/Manual sense)
If no +5v on pins 3 & 4 - comes from IC28 a DIP resistor array. Also
check accross cap C36 for a dead short to ground.
If no +5v on pin 1 -comes through R14 a 4.7k resistor.
I'm going to bet you need to replace IC5 a 7402 (or 74LS02) for
staters. It's the IC just above original battery locations on a Sys6
board.
If the switches ae working correctly, It's either that or the PIA at
IC18 (but you say that was swapped).
Post your findings!
Cheers
-Richard
Sprout
Thanks for the suggestions - all the voltage checks look good; getting
right at 4.9v, and close to ground (a few mv) as indicated.
Otherwise, had already replaced the 74LS02 (IC5), but dropped in an
extra with no change, so don't think I've got two bad parts. PIA was
otherwise a new part as well, and as noted the original tested out
fine using Leon's ROM.
I'm going to see if I can post a short video demonstrating the issue
to show first-hand what it's doing - I'll add a link to this thread as
soon as I've got it online.
Thanks much!
Brent
me
the flipper roms, so its reading them, and then the game on the other
and not loading IC14. My actual problem was IC14 rom was bad, so I'm
figuring that one of the address or data lines must not be getting
through on yours. Either the data buffer, that you should just jumper
out anyways and remove, traces shorted together, shorted to ground, or
something like that. How about scoping the address and data lines at
the eproms and seeing if there actually is activity, not just some
voltage. I didn't find my bad rom until I scoped it and saw no
activity, but I had 2 or so volts on the line.
Steve Yates
What happens if you put the game in audit mode with the other board
installed? Does it still cycle through the audits automatically. If
so, then this switch probably is stuck. It may not be the reason the
game is going into audit mode, but would be the reason you're
scrolling through the values.
I've never tried, but it's certainly possible having this button
closed could interfere with the quick power cycle getting past the
audit mode. It shouldn't cause the game to hang though when you have
batteries connected.
Steve Yates
Team-EM
http://REELpinball.com
Sprout
Update-
Swapped out IC's 12 & 27 last night, and that seems to have done the
trick - thanks to all who replied!
Brent