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Switch gremlins. Help!

Spandangler

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Hey folks

Corvette again!!!

Not sure if all the faults are related.

I’ve finally turned corvette on for the first time.
Before hand I’d tried all my mechs and boards in a donor machine so I know they were good. I knew I had some switch errors on my playfield which I’m struggling to sort out.

The race track was working fine. Now it seems none of the optos are working.
I also have optos out on the route 66 kick out (switch 57)

Other optos are working so I assume the ten opto board underneath is ok despite having no red led on. (Should it be on?)

I thought I’d try working through pinwiki, shorting the switch rows and columns on the CPU to see if I could get the switch to register, However nothing happens when I do that.
I was getting the check fuse 114 and 115 message to on startup with connections unplugged, which I gather is ok if you have the rows and columns connectors unplugged on the cpu?

Maybe connected, or not…
But if I press the right stand up kickback target (switch 83) it first registers switch 43 skid pad entry before registering 83.

And if push the skid pad standup (switch 82) it first registers trough 2 (switch 32), then ZR1 top entry before registering switch 83 (skid pad standup)

Worthy of note that all the ghosted switches are optos.

I appreciate that’s confusing 🫤 so apologies if I have worded it terribly.
Thanks Obi Wan Kenobis, you’re my only hope
 
First thing is do is swap the WPC-S board with a known working one and see if anything changes to eliminate the MPU board.
 
I had tried it in the donor machine. Was all good.
Some of these issues have arisen since it was switched on. Like the race track was working until yesterday.

Is the cpu interchangeable with wh20?
 
If shorting rows and columns on the CPU board directly doesn't show activated switches the CPU is broken. Is nothing showing a response?
 
Yeah that’s my thoughts. Switches work in test (except those above) yet, when I disconnect the rows and columns and and J212 as instructed on pinwiki, I get nothing on anything. Even using the parallel J206 and 208
 
Yes, why I am asking if nothing shows a response. If we can break it down to specific rows/columns we can identify the broken component.
 
In switch edge test I also just got a random activation of switch 34 which is trough 4 which doesn’t work in test
 
Could be dirty/failing optos. It should get triggered by the ball blocking the beam from the emitter when a ball is in place. If the emitter is failing/dirty it would give the same effect as a ball being there and blocking the light.

You can usually test the opto emitters using a phone as it will pickup the IR (I think) light being emitted. Pinball Heaven posted a youtube recently showing it in action.

Actually it was on ****book. - https://www.facebook.com/pinballheaven/?locale=en_GB
 
Have you looked at the switch matrix diagram and identified where all the issue switches are located on it, you might see a pattern there.
The only pattern I can see is they are all optos.
I’m suspecting the 10 opto board but don’t have another to test.

All of these boards worked in the donor machine.
I also suspect it could be some wiring from my playfield.
It was part wired by me and part by the previous owner who knew less than me!!
Was in a flood and hasn’t been turned on for ten plus years
 
The fact they are all optos could be a red hearing if they are all on the same column or row in the switch matrix, although the playfield being wired by two different people is a bit of a red flag.
 
ISSUE - But if I press the right stand up kickback target (switch 83) it first registers switch 43 skid pad entry before registering 83.

Switch 83 and 43 are on the same row, possible wiring or diode issue at switch 43, that would cause 43 to trigger when 83 is pressed.
 
ISSUE - And if push the skid pad standup (switch 82) it first registers trough 2 (switch 32), then ZR1 top entry before registering switch 83 (skid pad standup)

Again same row for 82 and 32 so would look at wiring/diode at switch 32, ZR1 top entry is 42 so again same row, 83 is on the same column as 82 so again sounds like a diode/wiring issue at 83.
 
Please establish that the CPU is working first - yes, worked in another game but this is easy to test and then we have a baseline. Lot's of Optos not working is usually 12V missing, that is coming from J116 pin 2/3 on the PDB, end on J3 pin 1/2 on opto board (LED should be ON there). Should be F116, also check F115.
 
If you recabled a lot of the switches, diodes the wrong way round could be the culprit as suggested by @Fantazia2 but the opto boards have plugs, you probably didn't touch those.
 
If you recabled a lot of the switches, diodes the wrong way round could be the culprit as suggested by @Fantazia2 but the opto boards have plugs, you probably didn't touch those.
I have a feeling a switch is wired back to front. But need to rule out the MPU first.
 
I have a feeling a switch is wired back to front. But need to rule out the MPU first.

I suspect multiple switches wired incorrectly, if the MPU was at fault wouldnt you get all the switches in a column or all in a row triggering and not just one or two in the same row/column.
 
Thanks everyone. I will work through the suggestions tomorrow when I’m in from work.

There is no red led lit on the ten opto board however I do still have some optos working.

I’m extremely grateful for all the advice thus far.
 
The LED appears to be connected to 12vdc coming from pin 2 on J3, so it should be lit if the board is getting 12v.

PinWiki suggest disconnecting J3 and testing all the other switches to see if gets rid of any issues.

So unplug J3 from the Opto board and if switch 83 still triggers 43 then I would say its a wiring issue, if it doesnt then could be an opto board issue.
 
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Maybe unrelated but I doubt it,
The motor control board under the playfield for the racetrack keeps dropping out. The 12v led flickers on and off.

I was saving that you from that fault for another day 😝 but it does point to a 12v issue somewhere
 
Maybe unrelated but I doubt it,
The motor control board under the playfield for the racetrack keeps dropping out. The 12v led flickers on and off.

I was saving that you from that fault for another day 😝 but it does point to a 12v issue somewhere

I would see if that changes with the Opto board is unplugged, and vice versa unplug that and see if that makes any changes.
 
- Test the CPU as described above to make sure the switch circuits are alright
- Unplug J116 on the PDB and measure 12V at J116 pin 2-3 PDB (unplugging that should remove power from opto board). J117 has 12V to display board and J118 to cabinet, those may pull down the 12V as well. If the display works, 12V is probably fine. The motor board actually runs on 20V so should not be causing this. We'll address that separately. Motor board gets its ground from J116 on the PDB though, so disconnecting that will also shut the motor board down.
- If that is OK unloaded, plug back in and measure again (probably still good as your display works)
- Now measure at the opto board and see what is there, J3 1-2
Report back
 
To add: There is an "Engine full stroke" opto board which is also supplied from J116. No idea where that is located, it doesn't have a control LED and carries two optos.
 
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