From what I've read and understand, it's likely a solenoid or a relay that's the issue.

It's only blowing the fuse when MPU and Solenoid boards are connected on startup. MPU lights look good and programming features perform as expected.

Not in audit mode.

Loud crack on power on and then 2.5A blows. Loud crack appears to be from the ball kick-out on the mid right hand side of the PF.

PSU tested on several points, looking like 5V is right on at 4.9v, and flippers measured 38V, when 28V is expected.

Measured other voltages but the flippers seemed high at 38V. Measured between ground at 3J2-3/3J2-6 and 3J3-4 and 3J3-5.

That being said, measured all relays resistance and found:

Flippers at 1.2 Ohm.

Kick-backs (? name ?) above each flipper at 4.3 Ohm.

Ball eject (right side of PF above kick-back on right) at 4.2 Ohm.

Mid-PF drop targets at 4.3 Ohm.

Pop bumpers at 4.3, 4.3, 4.1 Ohm.

Upper PF drop target at 3.8 Ohm.

Is this a good test? Should I move past this?

Something else I need to test?

TIA.

Coils. I meant coils. Coils tested with the resistances listed.

I disconnected the ground from the Eject Hole coil.

Assuming that, with a stuck coil, removing it from the circuit would not be causing the fuse to blow - I did this and the fuse still blew.

Am I incorrect?

This is the wire - and thanks to barakandl I did as he suggested - the Solenoid board connectors on the left side were all disconnected. From the top, #1 was attached. And powered back on, all good. Fuse good. #1 and #2 attached, powered on, all good. HOWEVER, #3 was connected and big crack, fuse blew.

I'm going to try to find what this #3 is connected to now. Curiouser and curiouser. Thanks all for some great advice!

IMG_0118 (resized).JPG

/ate dinner/*

Ok, I reconnected the wire to the Eject Hole coil, changed out the 2.5A fuse, and disconnected one of the wires from the Outhole coil (outhole is where the ball drains, right?) - and powered back on, then WHAMMO I blew the 8A fuse meant as fire protection per the Vid1900 guide from the Solenoid Rectifier...

https://pinside.com/pinball/forum/topic/vids-guide-to-bulletproofing-williams-system-6/page/2

Ok, so that likely saved my butt, thanks vid1900 !!

But this time, the 2.5A fuse did NOT blow.

Is my problem the 25.5 A rectifier for the Solenoid side?

When you say "take off the four wires and check it without dmm" - do you mean examine it visually, or was that a finger check - test using the diode test on my RMM for shorts? Check for resistance values? Probably a dumb question.

Thanks for that - heading to work now, will update later.

Interconnect was replaced - presumably - on new/reworked Solenoid/Driver board. Re-soldered (cleared out all old solder, flux, new 60/40 rosin core, 99% iso cleanup) on MPU board.

But yes, thanks for that - this problems' got me questioning basically everything. It's worth another look.

Yes it has, thanks - it worked intermittently, I saw the standard GI lighting, saw the MPU board boot (top led solid red), saw the attract mode run, and when things went south is when I started to play a game and it hit a pop bumper or a kick back, can't remember which, and then the pops/kicks would no longer fire. The switches would still score points, if I hit them with the ball, but generally things went south.

I'm also thinking that, as Mitch mentioned, the interconnects could be at fault as well. Even though I got a refurbished driver board, with the female 40 pin interconnect apparently redone, I did not replace the pins on the MPU board - but instead, resoldered them, examined for shorts, etc....

I may have mis-remembered the LEDs on the MPU.... I think that's what it's doing now.

> You mean the lower switches on the stacks under the PF?

>> The switches - (probably using the wrong terminology) - the leaf switches on each side of the kick-backs just above the flippers.

All that though, is something I can't reproduce at the moment.

I'm going to take the driver and mpu out this weekend and make sure the contacts are good on the 40-pinner on both sides... anyone know of a wiring schematic?

Meaning..... What wires - color and position - go to what spot on the harnesses and what are they connected to?

There may be creative wiring at work also.

That's very helpful, thank you.

Incredible find - those schematics and wiring codes are invaluable. Thank you very much!

So.... after a bunch of tracing down wires, voltages, ghost 'shorts', it turns out that we (buddy helped me find it) did have one busted diode - replaced with 1N4004 - on the first drop target set, had a few wires that re-soldered as they were hanging on by a thread, replaced every diode on every coil, but with Soleniod Drive 1-8 connected (aka 2J11 per the excellent Firepower schematics), each and every time the 2.5A fuse F2 would light up and burn out.

Testing traces, continuity of wires and coils, burning about 20 2.5A SB fuses (I knew this was going to be a slog so I bought a bunch of them) - and like a big baby throwing tools on the floor not once but twice - I pulled the Solenoid/driver board off. Examined each pin of the 'replaced' 40 pin female .156 pitch connector - they look like they were 'new old stock' parts, with original molex single contact points. Cleaned those contacts and more importantly (I think) cleaned the contacts (round pin - original) on the reworked MPU board. Plugged the *ast*rd back in, powered on, and the damn game started up. Sound. Displays. Lights, both GI and computer controlled, in attract mode, started working.

Several reboots, one reboot the displays didn't work, disconnected/reconnected master display 1J5 from MPU board, reboot, displays work. Then rebooted again after a bit of game play, and sound wasn't working.

Disconnected/reconnected 10J1-10J3 from Sound board, reboot, still no sound. Disconnect/reconnected 10J1-10J3 again and sound worked as expected.

Root cause I do believe now is that 40 pin .156 pitch connector off of the MPU board. The other items - diodes, wires, cleaning coils and sleeves - I'm certain helped. I KNOW the 8A circuit protection from the bridge rectifiers (the right - or lamp rectifier was replaced btw) helped to save my game.

Not done yet, but the game works now. And I'm very thankful to all who helped me.

@mitch @schwaggs @zacaj @vid1900 @cheddar @barakandl

Now I know why it's hard to part with a game you've spent a good deal of time with I must have 60 hours in this damned thing.

One thing I forgot - Marco Specialties does not have the .156 male end of the connector (square peg) that's got the correct height for replacing my MPU board connector.

Does anyone know of a reasonably priced replacement? I did order the female end (the end that goes on the solenoid/driver board) from Marcos. I have ordered from Digikey, Jameco, and Mouser in the past but don't seem to be having any luck finding any company with in-stock components with the correct length.

Found and ordered the .156 pins/male from GP. Good find, thanks.

I have redone the caps/resistors/diodes on the power board as sugested by Vid1900 - some of the caps were out @ GP but I have ordered what they did have. Appreciate the heads up on that, thanks again!