Hi everyone-

I'm making good progress on the Flash that I'm rebuilding. I have gone through and upgraded the power supply, cpu and driver boards. All three received new pin headers, male/female interconnect, caps, various PSU upgrades and the 0ohm lamp matrix mosfet upgrade. The game is running pretty stable now, however I have a weird switch column problem that is stumping me.

All switches on column 3 (spinner, pop bumpers and a few roll overs) do not register with the CPU unless the flippers are engaged. This is both in the diagnostics and during gameplay. All three flippers have been rebuilt with nos switches and flipper coils. The cabinet switches have also been replaced.

I can't quite determine why the flippers would have any effect on ONLY this column (all others are fine). Where should I be suspecting the fault? IC17 on the driver (N7406), or IC11 (PIA)? Or is it potentially a connector issue? The switch matrix headers have been replaced, however I didn't replace the connector (yet). Or is it possible its unrelated to the switch matrix entirely (since the flippers impact them being detected). Maybe a diode issue in the switch row?

Is it possible I have something miswired under the PF? I removed the harness for clear coating over the summer, but I left all switches soldered to the harness. Only the coils were cut and resoldered, verified wiring against the manual (although it wouldn't hurt to double check).

Thanks for any tips, this one is really stumping me!

Fixed my column problem, and BOY was it a tricky one!!!

First, I started by testing the switch matrix with the connectors unplugged and a 1n4004 diode. All of the switches in the column in question registered just fine (without engaging the flippers), so I was confident the issue was on the PF.

Next I moved on to the playfield, and tested all of the switch diodes. I snipped off one end, and measured one at a time. Much to my surprise, every diode was perfectly fine (I was almost certain I had a shorted one).

As I was investigating, I touched the spinner and felt live voltage (ZZAAPP!!) Took out my multi-meter and sure enough, there was 35-friggen volts DC on the spinner assembly. Traced it back to the column wire on the switch, and not surprising, all switches attached to that column were HOT with 35v dc (no idea how the switch matrix didnt' blow up).

So at this point, I know what the problem is, 35v on the switch matrix... but what stumped me is where the hell is it coming from! Obviously first place to check was wiring, checked out against the manual. Next step, disconnect the column wires one at a time until the fault clears. After doing that, I tracked it down to the right pop bumper. Again I pulled out my meter and the ENTIRE pop bumper assembly was hot with 35v DC! WTF! I dissassembled the coil bracket and inspected the coil... sure enough the coil wrapper paper wore down and the windings were shorting to the coil bracket. The scoring switch slightly touches the pop-bumper plunger and picked up the 35v DC.

It always seems to work out that way... the last thing you check is the culprit. Oh well, I can close that case! On to my crazy freezing/resetting issues (opening a new thread for that)...

IMG_3706.jpg

I realized I didn't post my fix... I just added a strip of electrical tape in between the bracket and the coil. The coil itself was fine, the wires hadn't shorted. They were just worn down to the metal, presumably from vibration and grit over the years.