Ok, so I've had this machine for over a year, really reliable. About a month ago I go to boot, display garbled then blank, won't boot. I look at battery, see a little bit corossion on one tab, I think "oh crap, knew I should have put in a remote battery holder". I take an MPU from my space station, same thing. Move my power supply over to see if it's that, same thing still no displays . So reading up it seems all I need is IJ17 connector for it to boot. Unplug everything but that connector, still won't boot. Moved the power supply and MPU back to space station to make sure those didn't blow up from whatever is causing the issue, boots fine.

Right now it makes a constant tone at boot, the 5v is on solid, the blanking LED flashes quickly once, the diagnostics never flashes. All fuses check out.

So if I know my CPU is good, power supply is good, wouldn't it at least boot? Only thing I can think of that's left is that the game rom (s) went bad. Would it be worth buying new ones to replace as a quick fix?

Side question: Obviously I moved the sound / game roms over when testing, but could I put the space station game roms in whirlwind to see if it would boot? Obviously it would have the wrong game code, but could it get it to at least boot?

Ok so I tried moving the game roms over, didn't fix it. Put space station roms back in it's own game, roms still working. Put whirlwind roms back in, now I'm getting the proper LED's (5v on, blanking on, diagnostics blinking), normal booting, still no displays. Plug everything back in, it's for sure booting to attract mode, can't start a game, still no display. Thinking about swapping the display from space station to see if it did indeed go bad, and perhaps there's a error code displaying I'm not seeing?

I'll have to check tomorrow, too late in the night to muck around. Looks like I'm checking pin 1&3 on 3J2 connector:
https://pinside.com/pinball/forum/topic/williams-system-11-bullet-proofing-thread#post-1539683

The display in my space station is a rottendog, which means low voltage (IE won't use the 100v).

I did try this, didn't help

So put my display in from space station, everything is lit up (zeros with x's in the middle). Since I know power is good, MPU is good, and I tried the space station roms, I don't know what's left other than maybe testing the thermistor in the power box.

Crap you're right.. I should have swapped in the one from fire! Why they would switch displays during the same system 11b is beyond me.

getting back into this. plugged earthshaker display in, still no display, just boots to attract mode and no game start. Checked inside the AC box, there is no MOV or thermistor installed (but the solder look clean and serviced by someone before I bought it), so I'm going to guess this isn't it if it worked fine for years. The power supply in the backbox is a newer remake board so not likely that. If I take the balls out and put back in the trough, it does kick them up.

Now I feel dumb.. all this swapping I forgot I popped out the batteries. It starts a game now.

I'm not good at reading schematics, but I did find this for system 11 display:
3J5 pin 3 (Sys11A) or 3J2 pin 3 (Sys11B) = +90 to +110VDC nominal
3J5 pin 4 (Sys11A) or 3J2 pin 1 (Sys11B) = -90 to -110VDC nominal

If my voltages are low at display and power board, I guess I have 2 options:
* fix or replace the power supply
* replace the display with a 5v rottendog display

almost no AC voltage at display, nor the power supply. F3 fuse checked out for continuity off the board, but it looked like it might be half burned out. Replaced the fuse, displays working again. I don't know why that popped, but I better play test it for a while to make sure. Thanks for the help!

new issues started.. cellar coil pulses at boot, then stays locked on.. And the lower right pop bumper fires every second. Turned it off for a while, decided I would check the cellar switch to make sure that's not bad, now my displays are out again (even after replacing the fuse one more time). I'm at the point where there seems to be a cascading list of issues I can't seem to troubleshoot. Time to throw in the towel and let an expert tech figure this one out.

No, it's booting.. I can start a game, but no display and the locked cellar coil and pulsing pop bumper. Also I've got the MPU from earthshaker in it right now, so can't be a board issue anymore. Those 2 coil issues were also with the previous MPU. Even swapped out the solenoid board from earthshaker just to be sure, no improvement. I haven't tried swapping out the game roms from another game again.

pop bumper stops firing. while the backbox was open i noticed on the interconnect board. j4 which is flash lamps, theres a spark between pin 14 and 15. looks like im hunting down a short somewhere.

There are technically 15 pins with the one missing one, but I'm counting from pin 1

CONNECTOR_BURNT (resized).jpg

INTERCONNECT BOARD (resized).jpg

no screws behind the board. Slight heat mark on back, but it's directly behind the ugly looking R4 resistor (I don't think it's a board issue, though I should replace that resistor)

front_interface_board (resized).jpg
back_interface_board (resized).jpg

So I borrowed the interface board from earthshaker, though not a permanent solution because the connector for the GI lamps below the display are different on each, but I could at least install it to see what happens. So booted with other board, no spark at J4, pop bumper no longer pulsing, but now the cellar is pulsing instead (perhaps the pins are slightly different for solenoid numbers as well), so it's possible there's another coil locked on but I didn't leave it on very long just in case.

So I'm guessing it's now down to an issue under the playfield.

ok so i removed the J4 connector from the interconnect board, display comes back, i can play a game minus the special solenoids (lower pop bumpers and cellar).

Looks clean on both:

aux_board1 (resized).jpg

aux_board2 (resized).jpg

all diodes check out for sure. As far as I can tell so do the transistors on both boards using the meter in diode mode unless I'm testing those wrong.

Already put the original board back in.. Tried doing a continuity test on the cellar coil switch, something didn't seem right (maybe stuck on)? Took it out, re-adjusted. The pop bumper isn't firing anymore, but the cellar coil still locks on. In switch test, it shows switch 06 as being on. Manual says that's left coin chute, but that's a different switch number.

Removing that wire, the coil still locks on.

Can't be power supply because I just swapped that out too just to see.. So yea, looks like I need to find a short under the playfield. Lord I hate tracing wires in bundles.

so I finally broke down and paid a tech to come over. The spark on the aux board deposited carbon between pins. He had to clean 4 traces and added 4 jumpers on the back. I realize I could have simply bought a new board for less, but watching a tech diagnose something is sometimes worth it.

It was the driverboard.