This is for a WPC-S Flintstones game. I've posted a similar problem a while ago but this one is a little more specific. I've done all the reading and searching but haven't come up with anything quite the same as what I'm experiencing. Hopefully one of the more experienced guys can steer me in the right direction.

I have a couple of switches that appear to be shorted along the column wires. In fact I have two different sets of switches that are doing this. The thing that makes me think it not a column switch short is that both the switches are at the end of the column (last single wire going to them) and there is an opto board in both cases that when unplugged, the problem goes away. Mind you, the switch is apparently shorting with both opto boards in either case.

Let me drill down a bit to give a clearer picture. When I go into Switch Edge Test and activate the 26 switch in C2-R6, the opto switch 36 in C3-R6 also fire. The same is true for the 54 switch in C5-R4 where it triggers the 44 opto switch for a 4 bank target (letter "R"). Everything that I've researched indicates that I have a couple of column wires crossed. I've traced, cut ties, and examined the wires all the way back to no avail and therefore don't think that's actually the problem.

I think this is all indirectly related to Solenoid 3, the Top Diverter Post not working during game play any longer. It was working for a bit, started to work inconsistently and has now quit all together. It has the proper current and fires in the solenoid test. To help shed some light on the situation, I'll post the Switch Matrix and a few schematics.

I've also tested the transistors, bridges and diodes on the Driver Board. There was one under the heat sink that appeared suspect which I replaced.

Solenoid Wiring.jpg

Williams_1994_The_Flintstones_English_Manual (1).jpg

Solenoid Circuit.jpg

Thanks for replying wayout440.

Yes, I agree about the column-to-column...that's actually what I was getting at as well. Like you, I don't think that it's actually related to wires being crossed being that there are opto boards involved.

I'll ignore the solenoid for now...maybe that problem will go away once the switch problem is resolved.

I'm not sure how to test the opto board by disconnecting the power to it...there is only one large IDC connector with all the wires going into it. I guess I'll track down the 12V wire and pull it out of the connector. Really wish I had splurged on an IDC tool now.

I was able to do a quick test over lunch. I did as you suggested, wayout440, and disconnected the 12V power to the opto board. I double-checked that switch 54 was still triggering switch 44 (4 bank opto board) before disconnecting the 12V wire. After disconnecting, switch 54 only triggers itself as it should.

I took the opto board off and visually inspected with a magnifying glass...looks fine. I put the DMM in Diode Mode and tested the diodes and resistors...they check out normal. When I have the 4 Bank Drop Target in test mode, all the switches show open and closed as they should. Okay....this means nothing to me at this point....any ideas?

Thing is, this opto board doesn't have a LM339. I've included the schematic for it above. Is it found elsewhere?

Sorry for my dyslexia above where I meant switch 44 and not 55 as typed (my original post is correct). I hope I didn't confuse you by that? When pushed in Swtich Edge Mode, switch 54 triggers switch 44, which is part of the opto board....with no LM339 chip.

Further, I want to be clear that this was tested before removing the 12V wire from the opto board...it does nothing now. Again, since removing the 12V wire from the opto board, which switch 44 is part of, 54 no longer triggers switch 44 in test mode.

I'm assuming you mean the CPU board?? I've checked the diodes on the opto board and they're fine.

Switch Schematic.jpgCPU Board.jpg

Didn't have a chance to do any further troubleshooting last night...had to build a logic probe...geesh. Guess I should have read the fine print before ordering it.

I thought I would post a couple of other pages in the manual. I'm about to dig into the board but thought I would see if there were any other ideas before I do?

That's a big help, wayout440! I was just reading up more on logic circuits as I was pretty sure I'll be forced roll up my sleeves here. I think the logic probe is going to be key here....when I finish assembling it.

You don't know the exact location of the LM339 from what I've posted by chance? I'm still learning how to trace these schematics without having my head explode.

For the sake of painting the whole picture, I've included the WPC-S Schematic for the CPU Board. I could be wrong, but it looks like I might want to replace the LS374SC chip at location U14. I'd have to steal one from another board until I'm able to order a few to have on hand. Correct me if I'm way off base.

Geez...it was right there in the Switch Matrix...forgot about that! I incorrectly followed J209-4 and 5 to U14...that's where I came up with U14.

Further, I posted the wrong Schematic! I posted WPC instead of WPC-S's CPU Board. Here it is for anyone who might be thoroughly confused by now....sorry about that.

wpc-s CPU Board.jpg

I think I'll change out all the diodes under the playfield just for piece of mind.

I was making some progress with unplugging the connectors on the CPU Board and was about to test with the logic probe. That's when lightening struck. Was following the pinball repair guide when it said to unplug J210...not good. I should have double-checked but my DMD is out now...grrr. Power is correct at the connections so I'm going to have to do some research on that one before getting back to my switch problem....piss me off.

Got the DMD fixed...just seemed to be a bad connection from the transformer. Carrying on now...

After finding a really good summary of all the common switch problems by PinMike here: https://pinside.com/pinball/forum/topic/switch-column-not-working I tend to agree that's it's not on the Playfield. Remember, the switch problem goes away on both rows when each opto is unplugged or the power is taken away to that board. I have visually inspected, cut ties and ran my fingers down each chain in question...I can't find anything.

I was going to steal an LS374SC and LM339 chip from another board but I think I'll exercise some patience and wait until these chips show up next week. Forgot to order the sockets....grrrr.

Out of curiosity, I notice that a couple switch's, 26 & 36 (Row 6) from J207 also connect to J212-2&3 along with 44 & 54 (Row 4) J209 connecting to J212-8. These are all the switches that are giving me issues. That just confuses the heck out of me. What the heck is J212 used for?

I have the same problem with Switches 26 & 36 as well...they go to U19. Tracing everything back, I see that everything goes to U20 (chip ULN2803) on the Column side...could that be the issue? If it might be, I don't have any of those chips on hand either.

Wish I could just swap out the CPU board from the Creature pin I'll be working on next. Sure would make troubleshooting a lot easier if a guy had a few spare boards kicking around.

Thanks Karetaker...I'll test this after work and report back. I was actually starting to do a similar test when my DMD went out. Nonetheless, I'm back in action and can test shortly.

...and to make it even more confusing...when I simply detach the 12V wire on IDC connection to the Opto Board, the double-switch error goes away as well. According to PinballMike's article and other suggestions, that indicates a bad LM339...which the opto board doesn't have.

As far as I remember Terry, those switches fired normally. I'm sure I would have wrote them down when I went through all the switches.

That's interesting... I checked all the columns against all the row as described in the article suggested by Karetaker....they're all good. None of them fired up with 2 switches at the same time. I guess that indicates that the problem is on the playfield....hmmmm.

Terryb, the voltage at switch opto is 14.2V. I'll check with a couple of other DMMs I have but I'm pretty sure this one is accurate.

It's all good with switch 37 and 38....each switch fires independently.

Does 14.2V seem a bit high for the opto?? I think I'll switch out the diode on the opto board just for piece of mind.

So it sounds like I can turn the page on the problem being with the CPU? Now I'm really at a loss. If I recall, one of the flasher lamps on the playfield wasn't firing properly. Maybe I'll tackle that one if it's still acting up and see if that changes anything. My goodness this one sucks!

I think I'm onto something. There's an independant board under the playfield. I thought it was exclusively for 7 opto through switches. Turns out J3 also has connections back to the switches in question. I've done a little testing before responding and it looks like I have a couple of resistors that are too far out of range. I'm going to see if I have anything that will work for them on hand and replace them if I do. There are a couple of LM339 chips on there as well.

Here's what the board consists of:

Opto Board.jpg

Opto Board 1.jpg

By keeping the opto board unplugged, 26 no longer trigger 36. And to recap, unplugging the power to the 4 bank opto, 54 no longer triggers 44.

Checked the resistors on the 7 Opto Board with my old faithful MM...they're fine. Going to test LM339 as soon as I find that test procedure again.

Okay...well I'm back at it. Did a lot of testing with continuity and voltages on the playfield. One of the Rows in question, appears to be low on voltage. Row 4, White/Yellow appears to be low on what it should be...10.2V. A few of the others that I checked appear to be closer to 13.7V. I traced it all the way back to the CPU board and checked it there...same thing, 10.2V at pin 4. I also unplugged the Lamp Matrix circuitry from the Driver Board just to be sure there wasn't some sort of strange grounding problem...no change. Correct me if I'm wrong but this seems to be too low...not??

Should have the LM339 chips this week some time. Never ordered any caps though...grrr. I'll have a look at the schematics and track everything down in that row...right??

Just a bit of an update. I was doing some further testing while waiting for my chips to show up. I was getting some wonky voltages at the J207 pins (down to 10 and up to 14). Just by chance, I noticed that as soon as I unplugged J212, the voltages were all identical across J207....hmmmm.

Traced J212 back to the Coin Door Interface Board. When I took it off and tested the diodes, I was sure I was going to find an open diode...not the case. After examining the board closely and testing pins and traces for continuity, I notice one of the traces was severed. I fixed that, plugged everything back in, and carried on. The voltages were good at J207 once again but it never seemed to cure anything else...grrrr.

Got my U20 chips in yesterday. I replaced it and fired up the machine into Switch Edge Test Mode and tested the switches...no change. Still haven't got the LM339's in yet but was hoping U20 would have made some impact on something...oh well.

Anyway, thought I would update just for the odd guy that might have been following. I'll let you know if there are any changes with the LM339's. Going away Thursday for a few days so I might not get back to it for a bit.

Oh, almost forgot...when I close the coin door and try to fire up a game, the DMD tells me I have...can't remember...coin door open...something, something, something. I can clear it by opening the coin door again and pushing escape, closing he coin door slowly by not activating Slam Tilt, and pushing Start again....sometimes....not always. Sometimes I have to repeat the process a few times. Anyone else ever run into this? I have a new bottom door switch but haven't really tested the upper one.