Wpc-95 errors on start up.

[Boof Head]

Ok so I’m getting some strange behaviour on my Medieval.

on start up after not playing for a few hrs I’m getting the same switch errors coming up.

left out lane left return lane

right out lane right return lane

right troll left loop high

left top lane

right bank top.

 

It’s these same switches every time. I do the switch test and remove the errors and they don’t come back until the machine has been off for a substantial amount of time. It does throw up a row 1 ground short every now and then at start up but goes away. Errors always stay.

 

Ive checked all switches and seem to be fine. No loose wires. Replaced u20 u13 u14 as per a few forum suggestions.

Any ideas?

 

I’ll just add that once I clear the errors the game plays perfectly. No switch problems at all.

[Arcade King]

Is there an opto boad under the playfield? Try removing the connectors and seeing if the ground fault goes away. Could be a leaking cap.

[Boof Head]

Well it wasn’t a leaky cap on the opto board because the cap was missing off the board! :lol

I’ve put one on and see if it makes any difference.

[Gemini2544]

Have you changed the back-up battery?

[Boof Head]

Yes. It’s holding all settings.

[Boof Head]

Turned it on this morning and these bloody errors is still there. :realmad:

[scotty]

get the oscilloscope out Edited June 18, 2020 by scotty
Light bedside reading is very interesting

[Railways]

Apart from the obvious like a ribbon cable or switch plug being one pin out or bent is their anything you did just prior to it playing up?. Cleaning it?, playfield to replace some globes? etc.

Just looking a the switch matrix and definitely not all in the one column or row. The most I can see are in the row of "6,s". 16, 26, 56, 86.

Unusual that it goes away but I read an interesting thread below that had a not dead switch but high ohms and it was enough to make the 2803A chip misbehave. A bit of light bedside reading below.

 

https://groups.google.com/forum/#!to...ll/BTxvCKhw5Mg

[Boof Head]

That’s it Jeff. I can’t explain why. It’s got me totally stumped. The row one ground short is only on start up. Go into switch test and all as it should be. Nothing activating anything else it shouldn’t. All working correctly.

Ive checked all switches,diodes both working and orientation, no loose or broken wires. All wires in correct position.

 

After I’ve tested the switch errors and they go away, they don’t come back until the machine has been switched off for a substantial amount of time. I’ve gone back to it after 2-3 hrs and it’s fine. Then go back in the morning and those bloody errors are back!!!

 

Ill check all switches again just incase I missed something. Eyes aren’t quite like they used to be. :119:

[Autosteve]

Power the machine down, pull the batteries, power back up to let it say "restored factory settings". Turn machine off and put batteries back in. That should clear it otherwise re-seat the ASIC chip.

If these don't clear the problems, next time the machine comes up with "Ground Row Short" leave it powered up and unplug the switch matrix input plugs and see if the error disappears. If it is a legit problem, unplugging should remove the error. If it stays there the problem is on the MPU board.

[Boof Head]

Power the machine down, pull the batteries, power back up to let it say "restored factory settings". Turn machine off and put batteries back in. That should clear it otherwise re-seat the ASIC chip.

If these don't clear the problems, next time the machine comes up with "Ground Row Short" leave it powered up and unplug the switch matrix input plugs and see if the error disappears. If it is a legit problem, unplugging should remove the error. If it stays there the problem is on the MPU board.

 

I’ll try resetting it. thanks

The ground short comes up for maybe 5 seconds then disappears. That’s the weird thing. It will have already gone before I’d get to pull the plug.

[Boof Head]

No luck with a reset and reseat of asic chip. :(

[Autosteve]

No luck with a reset and reseat of asic chip. :(

 

Can you get the exact switch numbers the machine thinks are faulty?. I'm seeing 16,17, 26, 27, 47, 71,68 atleast but I'm missing two and they aren't showing a pattern. Better to know the numbers to trace matrix problems. Once you have the numbers of the switches, power the machine down and pull the plug to the coin door and then try. See if this effects the switch matrix numbers or just adds more.

[Gemini2544]

Check the diode on the switches, I had a continuous & repeating error on I.J when I first got it, The diode on that switch was installed backwards.

[Boof Head]

Check the diode on the switches, I had a continuous & repeating error on I.J when I first got it, The diode on that switch was installed backwards.

 

I’ve checked all wiring, diodes and switches three times just in case I’d missed something.

I haven’t seen the ground short for 3 or 4 days now. The errors were still there though.

Frustrating thing is this morning for the first time it started with no errors. I’ve did nothing to it yesterday that could have changed that so it’s baffled me more.

Because it would only have the errors after a long period (6 or 7 hrs) of no use It has been like the car that won’t start cold. Fine once running and you could start it again when still warm but as soon as it’s cooled down the problem returns.

See what happens next start I guess.

 

[Autosteve]

It actually sounds like a capacitor that over time discharges and once charged, is no longer a problem but not being there myself means going through the steps to try and eliminate possible causes.

The front door is often overlooked and can cause strage intermittent switch matrix problems depending on how open the door is and the door is grounded so any switch can touch it. Something that is a lot harder to do for playfield switches considering the playfield is wood but still possible.

[Boof Head]

Funny you say that about the coin door. It looked like it was almost open this morning. I had to check it was locked. Might turn the game on and of with it in different positions.

[Gemini2544]

I'd be sending the boards to Ken for a good going over. It will save you growing more grey hair.

[Boof Head]

Well two days in a row now with no errors. Buggered if I know. :unsure

[KJS]

I have no idea either...just trolling :-)

[Boof Head]

Argh!!!!!!

It’s bloody back. :realmad::realmad::realmad::realmad:

[Boots]

try taking the batteries out and leaving them out for a few power cycles/days

[Manny65]

Or just sell the game .... as a project :lol

[Boof Head]

Or just sell the game .... as a project :lol

 

:unsure Might have to.

 

This time on start up the ground short row 1 came up for maybe three seconds then the left popper fired 4 or 5 times. That is new.

[ocyen]

Does lifting or jostling the playfield get the row short to reappear?

[Railways]

Does lifting or jostling the playfield get the row short to reappear?

 

Similar to the ol' wiggle method ;)