I could use some help figuring out this crazy behavior I'm having. Managed to buy a PinLED driver board and have had it act super strange in either of two pins (TZ or WHO). Specifically, columns with optos in them start to malfunction. On WHO, the MPF opto stopped responding completely. On TZ, the ball launcher opto and the rest of column 2 got stuck on, along with clock minute opto 0. When I put the original driver boards back in, everything works fine again.

I measured J116 and it came in at 14.1v which I guess is fine. The original boards are 13.8v. There's not a whole lot that the driver board does I can think of other than provide the voltage, so I'm confused as to what would cause a new driver to cause columns with optos in them to go haywire. Just to eliminate the MPU, I swapped those out and it made no difference. I would think that any problems with the switch matrix would show up using either driver board, but am open to trying whatever.

OK well if that's the case then it's something in addition to optos on TZ. So when the PinLED is installed on TZ, I get:

1. All of column 2 lights up when the coin door is closed
2. Clock 0 minutes (92) is stuck on
3. The auto-fire kicker constantly runs (while empty); that opto appears to be stuck on

Put the Williams board back in and all three symptoms go away.
So with that it's starting to look like both column2 and possibly row 2.

I also did a continuity test on all pins of J205, none of them appear to be grounded out.

I can install the board again a little later and report back on the T1 status with/without the ribbon cable... before I do, are there any measurements you need with the Williams driver in there that I can take first?

Re: coin door, its with the coin door switch.

Re: optos, it's entirely likely the optos in both games are original

I'm using all incandescent (except for a couple in the backbox) so I'm not worried about ghosting, but yeah I have heard the flickering is pretty bad.

Just checked those pins on J113, no shorts

I figured what the heck, I'll test J113 on the PinLED in its box... pins 1 and 3 are shorted with nothing connected.

Sorry, the first J113 test was the Williams board connected to TZ... that was fine (e.g. no external wiring was shorting anything, and the driver board is ok).

The second J113 test was the PinLED still in its box, connected to nothing... that one consistently shorts 1 & 3. I looked at the board and didn't see anything obvious; most of this looks like on-board component that I don't have the tools to do anything about anyway. I don't see any U slots on the PinLED, several ICs and the flipper relays. Happy to test whatever, but unless it turns out to be something simple I doubt I'd be able to service this board.

header's fine on the outside, i'd have to desolder it to look underneath and see if anything is touching (and void my warranty)

Don't I need that pin?

Hmm it looks like the top opto coupler's outputs are shorted in both directions (its upside down so its the left side looking at the board in the proper orientation). I suppose it could be shorted elsewhere, hard to tell with it on the board.

Bypassing pin 1 seems to have made everything work the way it should. Thanks for helping me track this down. A little surprising this passed bench testing but glad to have it resolved. Unfortunately, PinLED tells me they don't have any driver boards left. I'm not sure if they've stopped manufacturing them or if something else has happened to the company. This was apparently the back-of-the-shelf last one.