Playmatic Chance MPU Problem

[DarkSide]

Hi guys.
Got a few old playmatic pinball machines, and im trying to get at least
one of them working, but so far not much luck.
When turning on the machine the display on the front counts to 7, and
stops, checking the manual says http://edesigns.dk/pins/7.jpg
I did some probing around with my dmm, but nothing seems to stand out.
Any advice ?

Could it be the CD4023BE(34) or maybe the CD4042BE(24) ?

Regards
Ronni

[ChadTower]

If the chips are socketed I would start by replacing those.  Bad sockets often do that.  Next check for cracked solder joints, discontinued traces, and last replace the chips. 

[TopJimmyCooks]

PBJ: does yours have the hard plastic playfield?  If so, how is it?  wavy, super fast?  just interested and curious. 

[DarkSide]

If the chips are socketed I would start by replacing those.  Bad sockets often do that.  Next check for cracked solder joints, discontinued traces, and last replace the chips. 

Unfortunately they are soldered directly to the board, only chips in socket are the Rom and Ram chips.

I did lift the chips out to inspect the sockets and they look good, and connections was checked both the data lines, and all the others, nothing looks broken, or shorted out.

Im not sure if a faulty Rom chip can make that kind of trouble, its very hard finding any information about those machines, and the manual is not for much help.

[DarkSide]

Its ALIVE

Swapped the decoder board with a spare from another machine, the Chance counted to 7 on the display, and sprung to life

[ChadTower]

Nice!  Now you have the issue narrowed down to either the decoder board or the connector/harness from the decoder board.

[DarkSide]

Im a bit embarrassed, it was the bottom power connector to the MPU board, i did wiggle it, and nothing changed, guess i must have nudged it while changing the Decoder board.

The machine powers up now, and lights are flashning, playfield is lit, but when trying to run a self test it just Tilts, maybe its because its standing a bit crocked.

[TopJimmyCooks]

Level 'er up and let us know.  how bout some pix while yer at it, Pardner.  (end "Duke" persona). 

[DarkSide]

Well it turns on, lights starts flashing, and thats about it.

Pushing test in the cabinet does change a few numbers on the displays, and the lights flash different, but thats about it.

Pictures can be found here: http://edesigns.dk/Pin/ and a short video here: http://edesigns.dk/pins/Pin.m4v

[DarkSide]

Well, 1 step forward, 10 steps back.

Lights stopped flashing, fuses are good, test hangs at test 1.

Looks like the game roms are defective, so the machine is garbage.

[DarkSide]

I know this is kinda Pinball Repair 101... but....

First - check your voltages.

See if it'll boot up without anything hooked up to the MPU besides the power supply. 

Then, with the power off, plug something back in, and turn the power back on.  See if you can identify something dragging your power down or sending a shorted connection to the MPU.  In my experience, it's been displays, driver board, or a playfield connector.

I've owned ~40 machines and never once had a bad ROM unless the legs were physically falling off the chip.

Well i need Pinball repair 101, this is my first machine

Problem is the power for the mpu board is coming from the decoder board, did try without anything connected, and the machine does finish the boot up sequence, or atleast thats what it looks like.

The display on the front counts to 7, and then goes to 0, and thats when the flashing lights turns on, or more right it was when they did work, right now the machine turns on, counts to 7, goes to 0, and nothing more happens, something burned out is my guess.

Test mode still works, or sorta works, it gets stuck at test 1.

[DarkSide]

Okay, could not sleep so made a few tests.

Manual says check voltage on memories rom, thats spot on at 10.7 volt, check pin 3 on the cpu with the test light, also okay, checked ic 23, pin 10 and 11, manual says 2 volts, im getting 5.

But the manual makes little to no sense at all, pretty bad english

Edit: Good news is the flashing lights are back and working, there is a lot of bad connections in that machine.

[DarkSide]

Those old pinball machines can sure take up a lot of time.

Was probing around on the board today and found a dead SC158 transistor, i think it can be replaced with a BC158, will need to order a bunch of parts.

[DarkSide]

Parts are finally ordered, i just hope that i got the right replacements for those transistors.

[DarkSide]

Not sure if anybody is reading, but will still post my progress.

The machine now coins up, and its possible to start at game, half of the playfield is dead, but the flippers work, and the bumpers in the bottom, there is a few broken wires i need to resolder, and a bad connection to a relay, but its progress. !

[TopJimmyCooks]

I looked at the pix and I was impressed with how nice everything was set up and labeled wiring-wise.  All labels in English even though its a euro made machine.  should be fairly pleasant to work on.  My one bally pinball has all kinds of scorched connectors, battery corrosion, and insulation displacement connectors to deal with. 

The downside:  I've seen no source for any kind of parts/boards for the euro machines from the US dealers.  Did you say you had a parts machine as well?

[DarkSide]

I looked at the pix and I was impressed with how nice everything was set up and labeled wiring-wise.  All labels in English even though its a euro made machine.  should be fairly pleasant to work on.  My one bally pinball has all kinds of scorched connectors, battery corrosion, and insulation displacement connectors to deal with. 

The downside:  I've seen no source for any kind of parts/boards for the euro machines from the US dealers.  Did you say you had a parts machine as well?

Yes, i do have a Playmatic Party from 1979, it has almost the same parts.

Something did happen, the machine is totally dead right now, went into test mode, turned off the machine, now it does not even count to 7, it just show 1 or 2 in the display and hangs.

[DarkSide]

Well a few days later and no luck at all.

All fuses has been checked, all traces on the mpu board has been checked, changed a 4042 ic, but it still stalls at error 2, the strange thing is, the machine was working, turned it off, connected the score displays, and since then has it been dead.

I did try with everything unplugged, only power to the MPU board.

Voltages are also fine, im afraid that one of the Roms died.

[DarkSide]

I guess swearing at the board works, changed 4023 also, and now it counts to 7, and then hangs, so back to square one.

[TopJimmyCooks]

Keep plugging.  just got repair components (and a couple of parts boards courtesy of Louis Tully) to work on my Bally mpu.  I'm also going to try to get a missing display digit back on line.  Time for me to get soldering as well. 

[DarkSide]

For some strange reason an entire row of mixed 40xx ics was burned out, i really wonder how that could happen.

The machine is back online, or half that is, got a broken solenoid for the targets, can still coin up, but there is something fishy with the relay that turn the power on for the playfield.

Those Playmatic machines are not easy to repair.

[DarkSide]

A bit more progress, i think there still is something wrong with the MPU board, i cant get the test program to leave the first test, does not matter how many times i push the button.

Schematic is a bit weak on what controls the test functions, so its gonna be a pain figuring that out.

[DarkSide]

MPU Board fixed 100%, it was the CD4019 that was dead, and making the test program malfunction, fixed also a few bad connections with the relays, and the playfield is now working almost as it should, got a stuck solenoid for the POST targets, i just hope its not dead.

Game now turns on, displays are working, still a few bad connections on the headers, but other then that, finally 10 steps forward, and none back

[DarkSide]

Okay, i have a problem, one of the Solenoids/Coils for the drop targets is melted, and there is no where to get a replacement.

Its marked AC-1405, if anyone know where to source one of those i would be happy, otherwise the machine is garbage.

[DarkSide]

Pictures here:
http://edesigns.dk/Coil/

Its a pretty big coil.

[DarkSide]

Ill be more than happy to pay for shipping.

Cant measure that coil, guess it needs something special, when the drop targets pop up, should the solenoid not turn off again, if the power keeps on it runs hot, very fast.

[DarkSide]

Looks like i have a few faults in the decoder board, will repair that and hope ball dispenser, taca, and drop targets work.

Still no luck finding a AC-1405 solenoid.

[DarkSide]

Was working under the playfield today, and saw something funny, there was a Williams coil on one of the Pop bumpers, so if its possible to use a Williams coil one place i would guess it also be possible some other place ?

[smartbomb2084]

A coil is a coil regardless of manufacturer right? 

The physical dimensions and the resisitance of the coil are what counts and you can use a coil with a different resistance as long as it is close to what you need.

Measure the resistance of the working coil that is on the other drop target bank.

 There used to be  people around  who custom made coils. I once had two made for a BALLY ABC EM Bowler but that was back in 1990 when WICO was still around.

I know he can be a bear to deal with but I would give Steve Young a call at Pinball Resource, he is pretty good at finding obselete parts.  It can't hurt to try.

[TopJimmyCooks]

http://flippers.com/coil-resistance.html

take a look here.  your model is not listed, but info is given on how to match them up.  there's also the email for the compiler, I bet he is knowledgable.  You just need to A) find the right guy that knows what replacement coil will work, or B) measure it as noted by PBJ and smartbomb.

[ChadTower]

I still say going to RGP and asking around is the best first step.

[DarkSide]

Don't lose hope, I'd bet money it's a standard Williams coil.

For instance, Playmatic chime coils are really Williams score reel coils.

Was working under the playfield today, and saw something funny, there was a Williams coil on one of the Pop bumpers, so if its possible to use a Williams coil one place i would guess it also be possible some other place ?

Why do I even bother?

Once again - Have you checked your playfield to see if there's another coil with the same number on it?  Measure the resistance on that coil and buy a comparable coil from another manufacturer.

Drop target coils aren't fired all that often, you've got a -lot- of leeway in terms of what you can get away with so long as it physically fits. 

There is another coil with the same number, but when i try to measure it my dmm just shows 0, and i know the coil is working.

The manual says all coils are 280 ohm, but im not so sure if i can trust that, it also says the coil for the drop targets are AC-1006

[DarkSide]

AC-1006 is to small, i have no idea why the manual says it would fit, guess its a typo.

[DarkSide]

I did, 3 times even.

It shows 0 on my DMM, both in the machine, and out of the machine.

[ChadTower]

Then it is shorted and is not a good coil or you are not measuring it correctly.

[DarkSide]

Coil is good, maybe my DMM just cant measure coils.

[ChadTower]

That seems unlikely.  Have you measured it in both directions?

[DarkSide]

Yes i did, it reads 002 on 200 ohm setting, no matter what way im measuring it.

Coils works perfect in the machine.

[DarkSide]

No diodes are used in this machine.

[smartbomb2084]

Did you remove the diode first?

More Texas BS.

[ChadTower]

I am guessing the coil is shorted and it's only a matter of time before it eats the driver.  Could also be the resistance is within the margin of error on his meter or he has it on the wrong range.

[DarkSide]

Its nice to hear everybody thinks im a moron, maybe this is my first pinball machine, but still

Coil is working, or at least the target go up and down as they should, im thinking its my dmm thats the culprit here, but its also just a cheap one but has so far been good enough for my use.

Let me try to describe how im measuring it, dmm on, set at 200 ohm, probes on the terminals on the coil.

Got everything else fixed today, targets work, ball dispenser, rebuilt the Decoder board.

[DarkSide]

Just checked a few mixed coils from the machine and they all show the same on my DMM, so it looks like my dmm cant be used for measuring coils.

The Williams Coil on the Pop bumper is a G-23-750, and should be 3R9 in Resistance according to http://flippers.com/coil-resistance.html   

[DarkSide]

Drill a hole in the front of your cabinet and run a string to the drop target reset bracket.  Yank on it when you knock the targets down.

Also, invest in a self-ranging DMM.  3R9 in flippers.com language means 3.9 ohms.  What's the lowest setting on your DMM??

Lowest is 200 ohm, so it looks like i need a new DMM, if we say 3.9 ohm, i would suppose that its in the same rating the drop targets coils are.

[DarkSide]

You sir are brilliant.

Found my old dmm, and checked the coils, both came in at around 4.6 ohm, so i took a drill and at slow speed cleaned out the sleeve that was melted, fitted it to the machine, and guess what, it works.

Its a bit slow compared to the other coil, but it can be a matter of adjustment.

Both sets of drop targets work.

[DarkSide]

http://edesigns.dk/pins/droptarget.m4v Short video.

Yes i know the playfield is dirty

[TopJimmyCooks]

Awesome.   Nothing like some results. 

PBJ's an asset to this forum for the acerbic wit.  (Oh, and the pinball repair tips, too.)

[DarkSide]

Found the last two legs for the machine, and got it mounted, also took a few fast games and the machine works.

Still got a few lamps that does not work, and the plunger is not good either, i think the spring has gotten to weak.

[DarkSide]

Well not all is good, it happens a bit to often that the relays triggers an extra time, and the machine thinks its the 2 or 3 ball, when its really the first.

If its a relay fault, or something else, that i dont know yet.

[DarkSide]

You was right, it was that switch, but i do have a bad relay will need to get that changed.

Cleaned the plunger. but its still not good, half the time it does not work.

Will try and order one of those coils, just to have a spare, blew out a fuse today because of a bad connection, got that fixed, also fixed the sound, but i think i will disconnect that again

[DarkSide]

Something fishy is going on.

The Ball dispenser keeps activating every time the slingshots are activated, but only the slingshots, any thoughts on that ?

Short Circuit, PCB failure, Contacts ?

[DarkSide]

It does have a test program, and the strange thing is when activating that every coil on the playfield activates as it should.

But the ball dispenser keep trying to kick a ball every 10-15 seconds, it should only happen once, it smells a bit like a MPU failure ?

Edit: Sometimes when i turn on the machine it also kicks the ball out, so logic failure sounds possible, but it only activates once.

[DarkSide]

If it's engaging every 15 seconds that the game is on and playing, even without you knocking the ball around, you've got a board problem.  If there's a diode anywhere in the wiring associated with that switch, I'd replace it first.  It could be on the actual switch, it may be on a board inbetween the wiring and the MPU....

If that doesn't do it, my advice would be to defeat the ball trough switch connection at your MPU and see if the coil is still engaging.  It's sounding increasingly like you do have a board problem, but this way you can be 100% sure.

I will try and disable that switch tomorrow and see what happens, when game is playing the ball dispenser only activates when the slingshots are active, nothing happens when the pop bumpers, drop targets, flippers are used.

Its only on the test program it keep activating the ball dispenser every 10-15 seconds, can a dead diode really make that kind of problem ?

[ChadTower]

Way to check that is to really gap that ball trough switch or snip a wire to one of the leads. 

I usually just put cardboard between the contacts for this.

[DarkSide]

Okay a little update, took the switch out of the circuit, and it still does the same, tried activating the switches under the playfield, and it only happes with the switches for the slingshots, also just by activating them without the coil is active, followed the wire to the MPU at connector 03, but so far no solution.

Edit: Disconnected the wire for the scoring switches for the slingshots and now the game runs, but i cant see how a set of scoring switches can make the ball dispenser freak out, unless there is something wrong with the MPU board, ive also found out that its not just the ball dispenser freaking out when it happens, its all the coils that activate for a short period of time.

[DarkSide]

Im positive its a board issue, as it is right now i can't even start a game without the ball dispenser fires 3 times, and then game over.

Guess that was the end of that machine, i can do some board repairs, but i have no idea on where to look.
 
Edit: Changed the Decoder board, nothing changed, as soon the scoring switches for the slingshots are connected the coils start acting up.

[DarkSide]

Okay thats strange.

Had the game in test mode, pushing the switches, they should all give a different number, but those in the slingshots do not, they give 13, and that belongs to the ball trough switch

The slingshots should give 43, not 13.

Thats properly why the game thinks the ball was lost, and tries to shot a new one.

Edit: Any tips on how to fix that, wires looks good, no short circuits, so i guess its somewhere in the MPU or Decoder ?

[ChadTower]

Ah well, if all the coils are firing you've got a bad row or column in your switch matrix.  Make a note of which ones are activating and compare it to the switch matrix, you should find that they're all in a line together.

That. 

[DarkSide]

The Switch Matrix yes, but i have no idea where to find out where it is in this machine.

Can a defective switch matrix make the switches think they are on another location ?

13 instead of 43.

[ChadTower]

Can a defective switch matrix make the switches think they are on another location ?

13 instead of 43.

Yes, that's exactly what it could do.

[DarkSide]

Yes, that's exactly what it could do.

Any suggestions on how to figure out how the switch matrix works on something like a Playmatic ?

[DarkSide]

Pop out your driver board, test all the switch transistors with your DMM on the diode setting.  Replace the transistor that measures differently than the rest of them.

 

Maybe im stupid now but im not so sure if its transistors controlling that switch matrix, i think its 40xx.

There is a MPU board, a Decoder board, a Thyristor board for the lights, and a few relays.
http://edesigns.dk/Chance/IMGP7949.jpg

[ChadTower]

If 40xx are doing the switching then those chips are just diodes/transistors in a common ground package.

[DarkSide]

If 40xx are doing the switching then those chips are just diodes/transistors in a common ground package.

The question is just where i should look, there is around 30 40xx chips on that mpu board.

I know the switches for the Slingshots are connected to 03 on the MPU board, what leads to a 4072, then to a 4016, and a few more 40xx chips.

[DarkSide]

Clothes pins on the fuse holders!  I love it.  That's an insanely tidy backbox... good ol Playmatic.


Yeah, you're right, looks like your switches are controlled by 4042's?  Trace out the one connected to your trough switch and see if it's the same one connected to your slingshot switches.  You need the find the component in common.

 

Yea im not proud of those, but new ones are on order, gonna change all the fuse holders.

Will try and trace it out, should be possible

Edit: Traced the connection to the ball trough switch.

Ball trough switch connects to A on the MPU board, from A to 4081, then 4013, and 4011.
Slingshots connect to 03, then 4072, to 4016, to 4011, im not sure if im reading that schematic right, if anybody can take a look i would appreciate it.
 

[DarkSide]

Well i wanted to work on the machine today but im all out of 4042's, typical.

Hope changing those will fix that switch matrix problem.

[DarkSide]

Still not fixed, but game plays, it can just happen random that the machine thinks ball is lost and tries to shot a new one, even in the middle of a game.

It still seems to happen most often when the slingshots are used.

[DarkSide]

With the prices from here i would guess close to 6-700 USD.

The game is in Denmark, i just cant provoke the fault to show it self messing with the wires, connectors, playfield, only if i touch the score switch for the slingshots.

But as i said it does not happen all the time.

If i disconnect the score switches for the slingshots everything is working, well except its not scoring points when hitting the slingshots, so bad connection i really doubt it.

[DarkSide]

The slingshots are independent, and it does happen with both of them, or im not sure if thats the right way to write it.

It happens when touching the score switches under the slingshots, also without activating the slingshot itself, but it only happens at random.

I can play without problems, but if the ball activates the slingshot score switches to many times in a short period of time the machine thinks ball was lost, lets shot a new one.

Edit:

It does the same with all the switches in that part of the matrix, but they do show the right number in the test program, any ideas ?

[DarkSide]

Same idea I had before... replace the components associated with that part of the matrix.

Did that already, but same fault.

Can i ask you to take a look at the schematic, and tell me what you would change ?

[DarkSide]

Bit of an update.

Found out today the score switches and ball switch are on the same matrix, score switch is on 03, and ball switch is on 3B, both connected to the same 4072.

But i did change that, 3 times, also changed what was next in line a 4016, and a bunch of 4081 and 4042.

[DarkSide]

Got it !

Finally, it was a floating input, missing connection between 2 resistors, machine is working 100% now.

[ChadTower]

Nice!   

[DarkSide]

So what other Playmatics have you got to mess with?  I'm really intrigued by these things...

Only my Chance, got a Party also but its missing a lot of vital parts so im just breaking it for spares.

Got to get rid of those two Playmatic's and start on my Jurassic Park instead.

[DarkSide]

Short video: