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.