Grbgemen
Active member
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:
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:
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.
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.