Heavy Metal Meltdown help - switch matrix

[biglouieuk]

Evening alli wonder if someone can help me.

I'm helping my buddy fox a Heavy Metal Meltdown

I'm getting fault showing 4 switches as always closed. But I can confirm them open.

I was wondering if anyone knows how the matrix works on this machine as it's new to me and I've only worked on slightly later machines.

Test just cycles through as these 4 are closed. I notice that "M" is not showing as problem and it's the end of the column.

Wondering how best to start to troubleshoot.

 

[biglouieuk]

I notice the schematic shows Load Chamber switch should have a diode.



But on the switch, it disnae.



Would that be a bad thing? And might cause the matrix issue ?

 

[AlanJ]

i’d add it back. have you got schematics for the board that drives the switch matrix?

what happens if you unplug the rows and or columns from the board? ie is it a board issue ir a playfield wiring/switch issue

 

[biglouieuk]

Thx Alan.

If I pull the connector, I get no faults.

I'll check all diodes next I think, I've got 3 caps I can replace (others already done) and then triple check nothing is already closed.

That diode being missing could cause issues elsewhere? I'd expected to see a pattern!

Stuff I've read seems to suggest diodes and caps...

I'm hoping not board..

 

[Fubar]

The missing diode will cause other switches to trigger when this one is closed.

This page has some good info: https://homepinballrepair.com/pinball-switch-lamp-matrix-troubleshooting/

 

[biglouieuk]

The missing diode will cause other switches to trigger when this one is closed.

This page has some good info: https://homepinballrepair.com/pinball-switch-lamp-matrix-troubleshooting/

Ok, thank you.

I don't have any diodes the same, I have some "bigger" ones. Should be ok to test right?.as.long as we're stopping the back current?

 

[biglouieuk]

So that Load Chamber switch above, DOES have a diode and cap, just under the playfield.

But schematic says shouldn't have a cap!

Testing continues..

 

[biglouieuk]

Wondering what this part is? Slam?

 

[biglouieuk]

So that Load Chamber switch above, DOES have a diode and cap, just under the playfield. View attachment 141627

But schematic says shouldn't have a cap!

Testing continues..

Cut this cap, has taken two switch errors away on same row.

Continuing...

 

[andy]

Wondering what this part is? Slam?View attachment 141629

It should have a ball in it, if the front of the game is lifted the ball rolls down and makes contact with the switch at the far end to tilt it.

 

[biglouieuk]

It should have a ball in it, if the front of the game is lifted the ball rolls down and makes contact with the switch at the far end to tilt it.

And if it hasn't got owt in, should still be fine? Will pop ball in any way now.

Got a few caps to reinstate now too and two diodes I found looked dodgy. Unusual to find two, both on coin switches as well.

 

[AlanJ]

it’s the roll tilt

 

[AlanJ]

and needs a smaller ball

 

[biglouieuk]

And it seems someone has cut off the door slam.



If that's not attached, would that bust the matrix as well? It is shown in the matrix and is shown on a faulty row

 

[AlanJ]

If it’s cut then it is open, so can never close. so can’t be an issue.

 

[biglouieuk]

Gotcha. Understood.

The schematic says the tilt should have a diode and no cap.

The roll tilt has diode. The plumb Bob does not. The schem says the tilt should have a diode, I'm trying to work out if the roll tilt and Bob are actually all the same switch in the matrix.

Either way, no cap.. you can see diode on right of roll tilt and cap on left on bob.

 

[AlanJ]

roll tilt and plumb bob tilt are usually connected together, so they are one switch on the matrix. So the cap on the plum nd the diode on the roll tilt serve both switches, all looks good to me. But those caps can fail, so if that switch is causing issues, cut it off and replace with a new one.

 

[biglouieuk]

Schem says the tilt doesn't have a cap, that said, I've found a couple that look factory but schem doesn't have caps for them. Errors or late additions perhaps?

I have a diode that tests ok out of circuit but looks odd when across a micro switch. Pretty much the end of the line now, I've been through all diodes and caps (replaced all caps as my buddy had them already cut) still get same, 2 switches showing as closed in start up and test, even though they aren't.



Still that J and A, sometimes M the last 3 in that column. 'A' being the one that seems to consistently be a pita.

Have some bacon and come back to it I think

 

[biglouieuk]

Soo. I have it mostly working now. Just the two switched on the same row as.the tilt and slam that both seem a bit dodge.

I think he needs to get slam reinstalled and go from there perhaps.

 

[AlanJ]

When you are doing the switch tests have you got a ball in out outhole? if so try the tests with the ball removed from the outhole. It could be the diode on the outhole.

 

[AlanJ]

Oh just also realised it has 5 ball trough switches, so maybe test the diodes on each of those too. The reason these are more likely to be suspects is because they will be closed with balls in the trough, so making a circuit could cause issues if a diode is faulty.