Sorry little tech help needed here from the U.K. - I have a flakey drop target bank opto on WPT which when switched was still intermittent (fine in test, I switched the game on, triple reset on all banks again, put it back in test and that opto closed all the time again) going to replace the SMT4148 with a pin through hole one providing I can get it on (if not maybe use a tool to create a hole through the trace, we will see...)

I will swap boards before this to check it’s not a wiring issue before attempting this, but does anyone know the rating of this 4148 or have any other advice.

UPDATE

So I swapped the opto boards and the problem stayed on the board - ruling out the board.

So.... there were two switch issues with this when I got it, the right ramp made opto's and the king resetting, looking into the switch matrix... they all sit on the 04 return - now as switch 20 and 36 all work absolutely fine, so I am hoping this isn't a driver board issue or they would play up... Right?

Seems to be the little board at the back (520-5239-01) - which is causing the problem, if I switch the opto's on the right ramp made pair, it recognises the switch (as a different switch obviously) being made.
pasted_image (resized).pngpasted_image (resized).png

Updated

Shame no-one else has had anything like this - I have a new board incoming tomorrow, so will update in case anyone else has the same issue on whether this is the fix or not.

So... the new board turns up - turns out it wasn't the board at all, in fact it was a diode on the trough switch (this wasn't working either I found out), I have changed that, had it up in switch test mode, all switches working - lovely old job, start the game up - problem is back...

There is an associated TIP120 on the board for this row, but I never get any issues on the first wired switch - which leads me to believe that it cannot be on the board itself - it is always after the trough switch... could a bad switch itself cause the diode short on that and then upstream issues? I imagine taking it out of the circuit would resolve?

The closed switch issue continues - when the left switch is engaged - the trough switch is open, when I reset (open) the opto - the trough switch closes...

It's getting weirder...

If I engage ANY switch on the lower left drop targets closed - the switches act completely normally (Open as per below)

when ALL of the switches are open - these three switches act closed.

Screenshot 2018-11-20 at 20.08.36 (resized).png

Screenshot 2018-11-20 at 20.11.14 (resized).png

Progress - of sorts...

Jumper switch tested the board by jumpering the switch matrix - good as gold.

I then thought - hey lets jumper the rows back to the board. All golden but row 6. So I thought lets move row six around the pins, all it is doing is throwing out the drive voltage and getting a return, and hey ho, the closed switches moved around the matrix. This has to be a wiring issue - I have moved the opto boards around and it follows still, so as I say - must be that.

Is the only way to tell the actual path the wiring takes by physically following the wire around the playfield?

I couldn't see a block connecting the drive and returns for the switch matrix connecting to the backbox wiring, my thought was to jumper the drive connections between the block, then jumper the return to different connectors on the playfield, when it shows up, just go over that bit of wire with a fine tooth comb.

Replaced switch 36 opto and solved it.