I'm having a major switchatrix issue with my 78 Bally black jack. I have recently pulled the playfield out and cleaned waxed and re ringed the playfield. Also I have rebuilt the rectifier board and put a new cap on the solenoid board. Minor mpu corrosion removed and ground mod done to it. Before I started this the game was working fine. Now when the ball touches one of the upper lane switches a pop bumper or slingshot will also fire. These correspond on the same switch matrix return lines. The strange part is that all the return lanes are doing this even though none of the diodes or caps were touched. Also the ball only needs to touch the metal lane roll over mechanism to set off one of the pop bumpers it doesn't even need to make the switch blades touch. Seems strange for all the diodes to just short at the same time and strange that the ball just touches the wire form for it to happen. Something must be shorted some place but I just can't find anything. Any ideas?!
Bally Black Jack switch matrix issue
- Thread starter Mxzmark
- Start date
sylvain
Active Member
I would do this to troubleshoot this case:
- carefully look at the MPU's J2 and J3 connectors - make sure none of the pins are broken or corroded inside the housings;
- go into switch test and check switches individually - make sure each properly report for itself only; if not, check if issue is switch, row or column-related;
- perform another good visual under the playfield; it is possible that a diode, or lamp socket (GI) wire,
might have moved/bent to unexp touch a switch contact...
Incidentally, what ground mod was done? J4 connector pin on the MPU ? or TP1 to TP3 on the Solenoid Driver board ?
Good luck !
- Sylvain.
- carefully look at the MPU's J2 and J3 connectors - make sure none of the pins are broken or corroded inside the housings;
- go into switch test and check switches individually - make sure each properly report for itself only; if not, check if issue is switch, row or column-related;
- perform another good visual under the playfield; it is possible that a diode, or lamp socket (GI) wire,
might have moved/bent to unexp touch a switch contact...
Incidentally, what ground mod was done? J4 connector pin on the MPU ? or TP1 to TP3 on the Solenoid Driver board ?
Good luck !
- Sylvain.
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I don't see any wires or diodes touching any switch contacts. I did the switch test and it shows no stuck switches and all solinoids fire and show the correct switch #. I did both of the mods you mentioned as well as all the mods to the rectifier board. I have since removed the tp1 to tp3 mod on the solinoid board for troubleshooting with no fix. I will double check the connectors at j2 and j3 again but the looked ok last night.
If all the switches work correctly in switch edge test, I would suspect an issue on either the connectors between the MPU and the driver or an issue with the decoder chip on the driver. If you toss the game into solenoid test and all the wrong coils are firing or the same coil fires more than twice, this is where the issue will be.
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Should be the same but you'll have the swap the roms on the MPU in order to get the switch and solenoids to work/test correctly.
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It could just be bad pins in the connectors or cold solder joints on the headers that Sylvain mentioned, it's a common issue. You can put side pressure on these connectors while the game is on to see if the issue goes away.
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I checked and reflowed the solder on the header pins they seem fine. The strange thing to me is the fact that when the ball touches the wire roll over it causes the bumper/ slingshot to fire but the switch contact is not even being made (just a light touch), it doesn't do it when I press it down with my finger.
I'd be following Sylvain's suggestoins then under the PF, and look for anything that could be touching something that it shouldn't. If the switches register correctly in switch test and solenoids all work correctly in test....
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not the roll overs, but the gides on each side of the upper lanes? I'm wondering if there is a stray voltage somehow getting onto the guide (if they are metal) and conducting it through the ball into the rollover and back into the MPU causing the weirdness?
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