It is really hard to say without taking it out, cleaning it off, and looking for damage. The bottom two (on the right side of the photo) certainly look repairable as the damage appears to be limited to the transistors. As for the row that is completely scorched, it is a little harder to say. It certainly looks like there was a fire and the board itself may have been heat damaged to the point that a repair is difficult. The traces certainly were subjected to a lot of current and heat and they may have delaminated from the PCB.

It is probably repairable depending on your time, motivation, and skill set. It isn't too hard to find System 3-6 driver boards, and a lot of people repair them. Since you said you haven't repaired stuff like this before, it may be your best bet to send it off to someone that would want to spend the time on it (many people may not want to even mess with it) or look for one that is already working.

With your experience level you are best off buying a rebuilt board. Keep this one just in case you decide to get into board work as it could be a practice piece at the least if not salvageable with a lot of work. With patience you can find them for about $100 properly rebuilt on this site. You can find them on ebay for about $145 claiming to be properly rebuilt but trust me from my experience they are NOT even though the seller has a mile long listing bragging about their product.

This is true. I'd first try barakandl or HHasse here on the forum to see if they'd want to mess with it or if they have anything to sell you as a replacement.

Have to knock off all of the soot before you can tell if it is worth the time to fix, but it doesnt look good. I would find a different one that isnt burned up.

Back when i was fixing these for to sell outright i did $100 shipped for completely rebuilt all new headers, interconnect, lamp resistors, etc.... I just don't have enough time right now to do the amount of board work that is requested of me. I have 1000 projects goin on at once... stressful!

Alcohol is totally safe. You would get better results with denatured over rubbing.

Honestly, that board itself looks like a complete loss to m You're going to need a new driver board. 7 transistors that burned so bad they burst open, and I can already see some of board laminate was compromised. More importantly is that you'll need to find the root cause of what did that, as it's a very severe board failure. That kind of burning could have potentially caused a large fire.My guess is you'll also find a badly oversized fuse, or worse, on the power supply board.

I don't currently have any used ones available for sale here, but am able to help out with repairs should you pick up a used board that isn't working, or if other problems come up.

-Hans

If you don't mind unsoldering the relay, you can put the whole board in the dishwasher.

Dishwasher soap has fine sand in it, and this will gently bead blast the board.

Do this separate from your food plates.

I don't this this board is likely to be a good repair candidate, but you never know until the carbon is gone.

When i clean boards i go with dish soap and warm water first. Use a tooth brush to get in all the crevices. Next up i finish with Naphtha to remove all the water and flux. Things like the flipper relay should be desoldered off before cleaning, you dont want water trapped inside of it.

In your case i would start with a wire brush to try and loosen up the soot. Don't go too hard or you may damage more traces.

Rubbing alcohol is acceptable in place of Naphtha, but it doesnt evap clean (leaves white powder) and doesn't remove flux as well as Naphtha.

I have 4 rebuilt (?) driver boards. one done by one of the competent repair guys, put it in and it locked a coil and blew a fuse, bench tested it and all lamp matrix lights were on steady, retested it weeks later and the lights were off, not sure if something was stuck or what. I have not reinstalled it to see. I also have 3 more that bench test OK (all new connectors, upgraded 5W resistors). None have been "in game tested" to the point where I would feel comfortable selling to someone as 100% working until I install and verify all is working properly. If you are unable to find something you are comfortable with, let me know and I can game test to verify one of these for you.

Ed

PM sent.

These options may be out of your price range but should be pointed out; given your stated novice level new replacement boards are available:

1. James Kothout @pinballpcb.com sells replacement Williams System 3-7 MPU and driver boards (aprox. $200 USD the last time I checked). Bought one of his MPU's for my Firepower years ago and worked GREAT out of the box!!!
2. Rottendog's replacement System 3-7 MPU/driver combo board ( available from various sources; check for pricing but tends to range from $300-350 USD). This board has the primary advantage of eliminating the troublesome 40 pin interconnection from the equation (a LOT of problems happen in these games from that).

Like I previously stated these boards may be a little rich for your blood but I felt that you should know about them.

The transistor at the bottom likely burned and charred the board above it.

Repair vs replace... I'd suggest replacing. The odds of it being repairable aren't great... Especially without the right tools and experience.

I wish I had a repaired one ready, I'd sell you one at $100 - but I don't have one ready.

Those last pics helped seal the deal in my opinion: this one is a gonner. A good one to hand on the wall in the garage to show as an example why you don't overfuse your game.

Typical example of an overfused circuit. Buy a tested used board. Try Mayfair or a vendor at the next pinball show.

The solenoid circuit of a classic wms game.... has to be one of the most overfused circuits ever...

Here is my theory as what happens to there WMS driver boards. When the interconnect gets flaky, the game crashes and the blanking stays high, a coil locks and blows the fuse. Someone puts a 10amp fuse in there and the next time the game crashes and solenoid sticks on you get what the OP has.