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Bally Black Jack switch matrix issue

Mxzmark

Member
Feb 22, 2015
73
3
8
45
Lucan ON
Your right we have ruled out the roms. There's got to be a short on the playfield. With just power hooked up to the playfield from the transformer every metal switch is reading 7-8 volts a/c. Even when I pull fuses there is a small amount of a/c present. With all the strobe lines removed and just one return at a time hooked up ( all other returns removed) the switch on that return gives multiple switch closures. It's like voltage is getting on the entire playfield. I did note that while doing this test it only registered switches while I had one hand on the ball/switch and the other hand on the side rail. The saga continues!!
 

Mxzmark

Member
Feb 22, 2015
73
3
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Yes I used a screw in the corner and verified that the ground was good. I will put things back together and take a video for you guys.
 

Mxzmark

Member
Feb 22, 2015
73
3
8
45
Lucan ON
Here is a link to a video I just made showing the switch issue that I posted on YouTube. Let me know if it works.
 

Mxzmark

Member
Feb 22, 2015
73
3
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Plug looks good. I actually checked that last night. The ground pin is intact and has good continuity to backbox ground.
 

Menace

Well-Known Member
Staff member
Nov 14, 2012
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7-8VAC would suggest there is a GI socket touching something under the PF as GI is approximately 6.3VAC. I would look for a GI lamp socket touching a switch blade or something else under the PF.

D
 

Mxzmark

Member
Feb 22, 2015
73
3
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45
Lucan ON
Since the metal on the switch is physically touching the return line on the matrix if I touch the ball to it and then the side rail ( ie ground) would this not pull the line low and register as a closure on the entire return line? Does anyone have an early ss Bally game they could try the same thing on and see if they get the same results.
 

Mxzmark

Member
Feb 22, 2015
73
3
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Or do you mean the giant black box that the wall plug goes into. If that's what you mean this game doesn't have one. It's the only game I have that doesn't have it.
 

Menace

Well-Known Member
Staff member
Nov 14, 2012
2,440
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Santiago de Aurora
If you are measuring the voltage from the switch arm through the PF and the metal ball guide, your
Since the metal on the switch is physically touching the return line on the matrix if I touch the ball to it and then the side rail ( ie ground) would this not pull the line low and register as a closure on the entire return line? Does anyone have an early ss Bally game they could try the same thing on and see if they get the same results.

If the voltage you are getting is being measured from the switch arm and the metal side rail that the ball is touching, you just need to locate whatever GI socket is touching something it shouldn't be. Check the pop bumper lamp socket leads through the pop coil brakets and everything a GI bulb could come into contact with. Even check the GI sockets in the coin door. I'm pretty sure this stray volatage you're seeing is from a GI string. If the GI string was touching the ball guide I would think it would blow the fuse, so it's likely touching a switch or something else under the PF.

D
 

Mxzmark

Member
Feb 22, 2015
73
3
8
45
Lucan ON
Ok the 7 volts is gone from the switches, only 1.5 but I think that is the strobing from the mpu. Don't know how I stopped it but there must be something in a harness, I will further take apart and inspect. However the weird switch issue is still there. Luch when you get home try on your Supersonic it should be very similar to my blackjack. Now that I have the game all back together I played a dozen games and it seems to play fine. Starting to think this may be typical behaviour for these Bally games, how often do you really touch the ball to a switch and the side rail at the same Time... Never. Lol