Bally 7 Digit Display issues

Grbgemen

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Picked up a Skateball for my cousin and its got a few issues with the displays. Ive been through the guide on pinrepair and not sure if my issue is covered.

I have one display with the 10's digit out. Guide says:

* Game off, test all the 100k ohm resistors. Replace any out of spec or that are open.
* Game on, enter the display test (press the red test button twice).
* Connect a test lead to the score display TP3 (ground).
* Ground the collector of the level shiter transistors Q1 to Q6 (for example, on Q6 this is the junction of Q6 and R11). Remember Q1 controls the ones, Q2 controls the tens, and so on up to Q6 (and Q21 for millions on 7-digit displays). If the digit does not light, replace the appropriate digit driver 2N5401 transistor Q7 to Q12 (Q7 controls the ones, Q8 controls the tens, and so on up to Q12 and Q20 on 7-digit displays).
* If the digit does light, replace the appropriate level shifter MPS-A42 transistor Q1 to
Q6 (and Q21 on 7-digit displays).

Grounded it and it didnt come on so it looks like i need to replace the MPS-A42 transistor.

My other problem is that some of the displays have one digit that is faintly lit. Other displays have flickering in some of the digits. Guide says:

* Pin 36 on the display glass.
* Display board R21, R22, R29.
* Display board Q17
* Display board C2 (it can go open).
* Display board chip U1 pin 13 (replace if in doubt).

Reflowed those points, no change.

I have reflowed all of the header pins on the mpu, solenoid, rectifier board, and each header on each display. Also tried a different 5101 Ram chip and the two PIA's at U10 & U11 with no change.

Im guessing the next step is to just replace all the connectors? MPU and Displays.

In diagnostics display test, all the displays look fine. However the comma on two of them looks strange. Hard to explain. Kinda looks like its flickering.

One last thing, the voltage going to the displays is dialed in at 170v.
 
It has been my experience that if the displays look fine in Test and don't look fine in game play that you have a connector and / or header problem.
 
Thats what i am beginning to think. I went ahead and sent off and order to GPE. Will update this once i get them replaced.
 
Good luck on the fix, I also have a Skateball. It was in a VERY sorry state when I got it.

I ended up replacing the MPU, SDB, & rewired in a new rectifier board. Also had to rebuild the flippers, fix the middle drop target assembly, replace some entire bulb sockets, rebuilt the shooter lane kicker coil/assembly, installed a new leaf switch behind the middle bank, the list goes on and on haha. It's finally fully working now, I only have one insert light socket to replace and it will be 100% for the first time since I got it. Just waiting on the last of my parts order from PBR :)

My best score is about 2.5MIL so far on normal rules. That'll give you something to shoot for ;)
 
Well this one has seen better days. The cabinet is actually very solid with no major damage/deep scrapes/etc... The paint is flaking on the left hand side of the back box. The backglass is perfect with zero paint loss. The playfield is very dirty and has some wear. Mainly where the ball shoots across the center of the pf and near one of the pop bumpers.

The J3 harness on the rectifier board was hacked into three connectors. Two of them actually just had wires twisted together. Other than that, the boards are very clean. No acid damage on the MPU.

Looks like all of the lamps except maybe 4 or 5 are burnt out. Ive been going through and testing a good bulb and every time so far, it has lit. Must have got a sudden increase in voltage and killed them all.

I am hoping that once i get all the dirt and ball swirl out, it will look good. From there i will decide if i want to do any touch up work on this one. Like i said in the first post, its for my cousin and he doesnt really mind the wear.
 
Hi, Order the Bally display rebuild kit from Big Daddy electronics. They and GPE have everything you need to get any classic Bally up and running. --Rich
 
Hi, Order the Bally display rebuild kit from Big Daddy electronics. They and GPE have everything you need to get any classic Bally up and running. --Rich

One step ahead of you. Already ordered the parts needed to rebuild them just in case the connectors dont fix the issues.
 
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