Any idea when was the last time it was working?

Standard procedure for these is replace the big +5V filter cap on power supply, replace female side of interconnect, replace any sockets anywhere that are Scanbe brand. While working on power supply you may as well go ahead and replace the other electrolytic caps. Lately I have also started just replacing all .156" headers everywhere also, saves a lot of messing around later on.

As a side note, those boards look really nice, I can't really even see any discoloration by the lamp column resistors.

Vid has a good walkthrough here: http://pinside.com/pinball/forum/topic/vids-guide-to-bulletproofing-williams-system-6

I'm working on the game with him. When we bought it from the guy he emailed us and he said his kids were playing it and then it just quit working. When we arrived the rubbers were were dry rotted solid and he mentioned his kids were now in college. Oh well, we got a good deal on it as it is in pretty good shape cosmetically and will be a great piece. I like that it is Williams first solid state full production piece!!

We'll try your cap trick out. It's a shame I can't get one on Sunday when I have the time to work on it.

GLIst, My brother is on his way to go look at that powerboard. You specifically mentioned power supply and not the power board. Are there caps under the metal shield we need to get at?

No, I just meant the board. Sorry for the confusion.

Based on the description of things happening when you mash on the socketed chips it definitely sounds like you have some sockets to replace, in addition to whatever else.

Yeah, we were just seeing if all the chips were seated well and the last one I pressed was the one on the bottom left of that upper board. I believe the sticker on it says L2. I jumped when all the coils fired at once lol.

Does both the LEDs staying lit mean anything? I noticed there were error codes with those two but it seamed like those were for after pushing the diagnostic start switch. That button doesn't do anything. If it isn't for that I think the error code is for the CMOS

Yeah, means your board is locked up. Can be for any number of different reasons, start with the +5V filter cap, MPU board sockets, and female interconnect, and hopefully you will be working after that.

Ahh, so you got the Ebay find. I was watching it. Looking to pick one up since its war the first game I ever played in the 80's.

When it boots up count how many times the diag light on the MPU flashes. That will tell you which are to look.

Flicker: MPU reset good, program booted.
1st Flash: ROM Checksums OK
2nd Flash: U7 6810 ram OK
3rd Flash: U8 5101 ram OK (U8 & U13 on mpu-200)
4th Flash: U10 PIA OK (see details for caveats)
5th Flash: U11 PIA OK (see details for caveats)
6th Flash: U12 555 Display interrupt timer OK
7th Flash: Zero crossing interrupt detector OK (solenoid voltage present)

Yeah on that eBay deal. The cabinet was in such good condition in the pics I almost didnt bring it to my brothers attention thinking someone repainted it. The back glass appeared pristine as well in the pics. Turns out its not pristine once the lights are on but still damn good for its era. There is some crackling in the paint that can only be seen with lights on but that is about it. The play field looks great with a little wear near the left eject hole. I hear my nephew cleaned and novused it today and it looks awesome. I can't wait to get there to see it. If we can work out these board issues it will be a steal for $240 in this condition. I'm/we are so stoked to own this pin

This info is for old Bally/Stern, Hot Tip is a Williams System 3

Here, it would probably be helpful for you to read through this: http://www.beerorkid.com/pin/System%203-7/
Apologies to Clay, it is for a good cause but if he wants I will remove the link

Wow that looks in depth. Should be a good read. Thanks

Wow, I must have had Brain Freeze. For some reason I always thought it was a Bally.

Look for burned resistors on the display driver, I don't have the numbers in front of me but the two rows of 7 near the top of the board (10k I think?) like to burn or fail and then you get missing segments on master/1/2 or 3/4.

We checked the resistors and they seamed to have checked well. I guess we missed one or have our multimeter on the wrong setting. It is very strange. None of the displays were working correctly but 1 & 2 were missing the same thing and 3 & 4 were missing the same things on the display. When swapping them to see if the problem followed the display or stayed the same we moved display 1 to the 4th position. Bam - 3 & 4 worked great. When putting 4 in the 1st position 1 & 2 worked worse but again in the same manner. I am assuming display 4 draws more power than the others as it seems to always make the others go bad in what ever section we move it to. I don't have much experience working with these guys so suggestions like the resistors is appreciated.

After triple checking the resistors, they all tested good. Some of them didn't really pass the eye test as they looked darker than the others. We replaced three of the bank of 7 that control player 1& 2 that looked to be the worst. That didn't help. So we decided to replace all of them and have 7 new resistors. Surely, we thought, this would work. Nope! The exact same problem exists. One of the resistors gets hot as hell. I was just touching them to make sure they were soldered good and burned my finger. Scared the hell out of me lol.

So, what would cause one to over heat so much? They run straight to a little white IC chip next to the main display. Could this chip be the problem or do you think we aren't getting enough power from the main power board?

Unfortunately I think the usual next suspect is the UDN7180 chip which is hard to find / expensive. Looks like that would be IC9 based on which displays are giving you issues.

With the resistor getting super hot it sounds like something is shorted somewhere, I would start by unplugging displays 1 and 2 and verifying that the display on the master board still has the issue (this tells you that the problem is isolated to the display driver board), then if you don't see any problems on the board or master glass I guess all you are left with is the UDN chip.

We had them unplugged last night and I'm fairly sure the master display didnt get any better. Could the short be inside the chip where we can't see it? Are you saying that if the master display is still not right that it is probably that chip?

Well assuming the short is in that chip we are trying to source one now to fix the displays. The new problem is... When we got the machine the right drop targets didn't have a coil. We moved the coil from the clacker credit unit over as it had the same rating. We happened upon another coil in our storage box with the same rating as well so we replaced the clacker credit unit. It worked well for a day. Now it fires and stays energized as soon as the machine is powered on blowing the coil fuse after a short amount of time. It is not getting the signal to fire from the coin switches so what else would make that coil fire? We've looked everywhere for a short we can think of.

For the display, it looks like it is probably either the chip or the master display glass itself. Missing segments can also be bad connection from the master display board to the MPU, but if you have a resistor cooking it sounds like something is shorted.

For the coil, sounds like a shorted driver transistor on the driver board. I would check the diode on the replacement coil, but it should be there and intact if the coil ever worked at all.