Hello All,

My first post. I guess I've been lucky so far and able to fix my issues in the past, but this one has me confused.

To start, I did have some very light alkaline leakage. I brushed off the bloom and played a few games with no issues. I thought I’d neutralize any remaining alkaline so I pulled the board and dabbed on some vinegar solution. Reinstalled and got a ton of problems. Ground short row 1 stuck closed, Row 1, 3, 4, 6 and 7 errors, clock broken and ball popper stuck. Flash lamps behind the gumball, in the right corner and next to the slot entrance are now stuck on. Random coils firing, etc.

Seemed like the CPU board was toast so I replaced 74LS374 with no change. I punted and bought a new Rottendog CPU board… No change. Grrr.

I could find no wiring issues under the playfield. The clock HAD been working well (PinLizard board from maybe 15 years ago). I unplugged it and it cleared up many of the issues. With the clock unplugged and all flash lamp and coil plugs removed from the power driver board, I now get one error: Clock Broken.

So the issues now:

• I tried to start with the coil and lamp plugs installed on the power driver board and it instantly blew the 8 amp fuse before the transformer. (I pulled them back off)

• Left magnet and gumball entry optos not working in switch test

• Power Driver TP 8 reads 36 V, fluctuating to 7 (should be 18 v)

• Clock broken (disconnected)

• DMD is scrambled on initial start-up but works fine after (Didn’t used to do that)

Not sure what to try next. My first thought was the custom 10 opto is blown and to replace the LM339 chips. And / or to replace the 2 opto pairs that aren’t working. Looks like also the 18 v circuit needs help (BR1 and associated components).

I guess my main concern is what did I do to cause so much carnage, and am I causing more issues trying to diagnose things? Thankful for any ideas.

Thanks for the logical suggestion Coyote... If only it were that easy. I've re-seated and double checked all the ribbons many times. All are correct. None are plugged into only a single row of pins.

I would consider bad ribbons after 25+ years, but I wouldn't think that a bad wire or 2 could cause the number of issues I have.

-NFL referee voice-
"Upon further review... Coyote was right on the first post. Replay first down".

Thanks Coyote and everyone for the replies.

Data cable to the 8 driver board was reversed on the left side of the mpu. I never did that before because the ribbons are all molded into a particular shape after 25 years. That ribbon appeared to be oriented the right way but it was 180 degrees out.

There had been a paper holder that suspended that ribbon. It ended up in the bottom of the cabinet and let the ribbon fall down. It changed the orientation. Lesson learned... Follow the red stripes. Pin 1 to pin 1.

I have to say these electronics are pretty tough! After the torture I subjected mine to, the damage is minor. I just played a game. The clock even works now! If nothing else, my post documents the specific symptoms of reversing that cable.

I still have a few optos out. It won't let me load the gumball, and the gumball entry is dead among others. Do you think I fried the 10 opto?

Yeah. All else seems functional but the select optos. A bit easier to diagnose than the multiple issues I caused before!

Switch test shows non functioning switches 81, 83, 84, 85 and 87. All on plugs J3 (receiver) / J4 (emitter) on the opto board. Looks like they all pass through U2 and U3 LM339 chips on the opto board.

I'll double check my plug connections to the opto board. If all checks out, would it seem logical to replace those 2 chips?

Yes. There is power to the opto board. All the optos that pass through chip U1 on that board work fine.

Thanks for the caution, lyonsden. I planned on verifying dead chips before replacing.

I unplugged the connectors and the pins seemed to read ok on the logic probe. So I plugged them back in and all the optos are back up!

I possibly had a connector not really on the pins? Not sure... Just had cataract surgery so close range vision is a bit off. Anyway, seems to be working 100%.

Thanks again everyone for your help.