Hi, I just picked up a Williams blackout and the person I bought it from had it plugged in and all the GI lighting was on and a buzz coming from the speaker. I packed it up brought it home and for the last few weeks I've been cleaning and tweaking. I know it doesn't work or start a game, however before I plug this in again I want to see if there's anything I should do beforehand. I noticed the knocker coil was melted and they had clipped and taped the wires. I suspect a bad transistor on the driver board. All other coils look healthy and clean. I removed the MPU and the Driver Board and re-flowed all the pins at the 40 pin connector. All pins and female connectors look clean, no burns or heat stress detected. No acid damage. All boards look remarkable! Does anyone have a chart showing coil/ transistor assignments? i e. Q1, Q7 etc and which transistor fires which coil? I'd like to find the transistor that matches the melted knocker coil.
What should I be looking for at power-up for LEDs on the MPU, or is that even of any value on a system 6? What should it do when power is turned on, dings, sounds, etc? Any other input someone may have would be very appreciated.
Many thanks in advance! Scott

Thank you, these docs are helpful. I have scanned the driver board schematic and cannot locate Q41, knocker coil transistor. Solenoid chart shows it as Q41. Coil was melted to the Mount and the wires were clipped when I bought the game so I figured I'd start there....

Thank you Zacaj, I decided to drop the boards off to a local repair guy I had no idea there was one in town! I like to support local community businesses when I can. He took all three boards. In the meantime, I triple thicked the backglass to seal it, ordered transparent glass paint to touch up the missing paint, installed new rubber, lane guides, target and spinner decals and whipped up a couple of custom apron cards (see photos)...coming along just fine! Just have to order a few coin door price plates, jeez those things are pricey! Marco wants $8 a piece for those!

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Can anyone say if I can substitute a 26-1500 coil for a burned out Williams 23-900 coil? It's for the knocker. Very little use. I understand that there are 1500 windings instead of 900 which makes for more resistance which puts less strain on the tip transistors and uses less energy. As long as it fires the plunger and I hear a decent knock it's fine by me. I just have a brand new coil and I'd hate to have to just go buy another one for no reason if it won't do any damage to the driver board.

mof, The yellow bumper caps suit the upper playfield well. Breaks it up nice! I ended up spraying the yellow flipper bats a cream white, re-made the diagnostics label inside the coin door.. (See before/after pictures) and the inside cabinet is now wired with a lamp socket near each flipper button for rgb color changing led bulbs that will light up a pair of clear flipper buttons. Next I'll run a socket hidden under the ball trough and illuminate that area. What color bulb.....hmmm comin' along...!

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Ok, thanks... I will simply order the correct coil and be done with it... I appreciate the feedback sir!

Okay got the correct coil for the knocker and that's been installed the circuit boards came back from repair and I still get no boot up. Got two solid red LEDs on the mpu and a buzz coming from the speaker and that's it. All the general illumination is on and looks good no attract mode no boot up. the repair shop had these on the test fixture all day and apparently they were reading correctly the only thing I did not give them was my soundboard could that have anything to do with this? Really feeling frustrated I've never not been able to get a Williams game running. Any assistance from anywhere on the planet would be very appreciated...Thank you!

Nothing. Displays are dark...

The repair facility had both the driver board and the mpu connected together and running most of the day I also gave them the power supply board and they checked that and that was healthy. Where do I check voltages specifically? I'm pretty good with a multimeter. Perhaps you can share a step-by-step...I will check the ground strap as well.

So I'm looking for the output test points for all of these different voltages on the mpu?

The mpu is on top and the driver board is connected underneath two screws attached the mpu at the top and two screws attached the driver board at the bottom I don't have screws in the middle where the interconnect is because I read somewhere where you don't want that touching the metal behind it so I put a piece of thick tape over the bracket so the back side of a board would not short out.

I found this chart in the Williams manual I'm just not sure where to check the +5 volts or 12v it does not say how or where. I also did what the chart suggested and completely removed the driver board and powered the machine back up. The two red LEDs still remain on. No boot.
I guess I just need someone to help me one step at a time on how to check various voltages and at what spots and how this affects boot. Thank you in advance and apologize for being a bit green...S

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Hello! TP1 upper left is 8.35 VDC and TP9 is 3.71 VDC. The ground at TP 10 reads zero. Thank you kindly for offering to help...

Disconnect the MPU: Not sure how to disconnect the MPU. I see the two black circles at two different connectors in the diagrams....I tried disconnecting J2 at the top left side of the CPU board then checked for 5V. At TP9, It's still around 3.6V....

Ok, here's something... I was reading the Williams three through six pin wiki and was measuring the giant blue capacitor on the power supply and noticed that the bottom lead had come away from the capacitor! So I was measuring voltage like it said to do and found that it was disconnected! I dropped a little hot solder as a temporary fix and now there's 12V and 5V and we're in attract mode.
And just now a relay started clicking in the back box and everything went dark and flashed on the playfield I'm not sure if that is a power problem or if that is what the attract mode looks like for blackout. The loud hum is still in the speaker and half the displays now light up. Specifically, the master display and player 2 and 4 show all zeros. Very encouraging. Could that large blue capacitor on the power supply have been the cause of lower voltage on the mpu?

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Very good ideas I will order a capacitor kit for both the soundboard and the power supply. Yes, game credits up, knocker fires, although weakly, and game starts. Targets register, no sound, still has loud hum/buzz coming from speaker. Two of four displays are out so can't see score rack up in player 1 and player 3 displays. The two diodes you were mentioning, are those the two large black ones at the bottom left of the large capacitor? If so, do you know the part number?

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Ok, I swapped one of two known good displays to all four-player harnesses and there is power to all of them although the fourth digit is flashing on each harness that I connected a good display to. So it appears that two of my four displays are bad, they don't light up in any position.

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Ok, I tried a known good display on all four player harnesses and the harnesses all have power. Apparently I have two bad displays. I moved the two good displays to the player one and two positions. The fourth digit blinks or goes out on all 4 player positions on both good displays, and the first digit in player one position sometimes changes to a 6 every few seconds. So, I assume it's something in the master display board and not the wire harnesses themselves that needs to be addressed. I'd like to stop and thank you both for carrying me this far, I really appreciate it. My gloom changed to rays of hope as things start to come around!!

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Ah yes, you're right. The 600,000 default high score alternating in the display. I'm trying to pinpoint the resistor(s) that need replacing. How do I check a resistor, power on/off, setting on multimeter? I found a system 6 display schematic here on Pinside.

Ok, I just ordered the sound card repair kit and will replace all the capacitors. I also ordered the power supply repair kit with all four new capacitors and the diode kit that goes with it.
There is a sound ROM in a socket and a long 40 pin IC in a socket on the main board and 3 socketed 24 pin chips on the speech board. Which is a PROM? Or should I take everything that has a socket off and clean the legs? I will be looking around for original replacement displays andI also looked into the Wolfpac set for $100 if you want to solder your own components. Where and how do I test the high voltage for the displays like you mentioned about the space shuttle?

Here is the picture of the upper left of the power supply, there are four + symbols that look like test points. Could this be where you test the voltages?

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First four pins read zero. Last pin in the 6th position reads 5.0 VDC. as far as the sound card goes I pulled every chip off cleaned the pins very well, and reinstalled them, still no sound no speech. I did notice however if I jiggle the far right wire which I think is the power inlet wire for the sound card, it's a long triple gray wire and it comes right from the transformer, that the loud buzzing has now disappeared so I'm not sure if it's a connection issue at that harness. What is the voltage that is supposed to come out of that triple gray wire? Is that something I can test?

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