One of the dip switches on the mpu turns on or off the credit/match display. Check the manual.

Switch 20 on for credit display, off for no credit display (for Paragon but think it's same for HG.)

That wouldn't turn off the ball count though?

If you have a logic probe check what the display digit enable address (display connector pins 4-9) and display latch (pin 15) and blanking signal (pin 10) are doing in both test mode and play mode. (NOTE: high voltages on J1 pin 1 and some j2 pins and on board so please be careful or check them at the mpu end --- do you have schematics?)

Could be always sending a blank, or not addressing the displays in play mode ?

The only signal that is unique to that display is it’s latch signal pin 15 Everything else is shared. But works in test mode...Hmmm. Think Pooh Bear...

So in self test the rightmost digit of the credit display does work? It's off in the Pic but

666 ... number of the beast. There’s your problem right there... your machine is possessed!

Will keep pondering the symptoms...

What’s different in test mode than in play mode when it comes to selecting the display digits that it turns on? Any of you emulator guys able to look at that?

Somehow it seems to be triggering the blanking signal only when it’s calling out those two digits... but only in play mode.

I’d say the blanking signal is tied to one of the address bits that choses either of those digits... but that doesn’t explain how it still works in test mode.

Blanking signal is global to all displays. As is each digit. Could technically be an issue with the RAM but I'd expect it to count balls wrong as well in that case

I'm thinking it's the Display Digit Enable address lines.

How's about if J1 pin 4 and 5 are swapped or more likely shorted together?

Theory...
1) all 6 digits of display 5 are used in test mode, but only signals 4 (digit 1 - ball in play) and 7,8 (digits 4 and 5 - credits) are used in play mode
2) if addresses are swapped or shorted, you wouldn't see it in test mode, all digits would still turn on, just in wrong order or at the same time, which we can't see fast enough, especially since they are sweeping the same number through all the displays.
3) since digits 2,3 and 6 (signals 5,6 and 9) always need to be blank in play mode, the MPU needs to blank them every time it sweeps around all the digits
4) if signals are swapped or shorted, then when the MPU is telling digit 2 (J1 pin 5) to go blank, it's telling digit 1 to go blank instead or at the same time.
5) if the signals are actually swapped, then I'd think the ball number should show up in the second digit, not the first digit. If they are shorted together, then the MPU tells digit 1 (and 2) to display ball number, but then immediately tells them both to blank when it tries to blank only the second digit.

Other possible symptoms
a) if the signals are swapped at the MPU connector, then you should see digit 2 data showing up in digit 1 data for all of the scores... do you only see zero's in the first digit on the displays or are you getting other numbers? 10, 20, 30, 40... would be 01, 02, 03, 04..... If they are only swapped on display 5 connector then the other score displays would be OK, and you would only get blanks in digit 1 (although, I think you should see the ball number in digit 2)

b) if the signals are shorted at either the MPU or display connector, then it should affect all score displays... 10, 20, 30 may show up as 11, 22, 33, or 00, 00, 00 depending on the order of updating the digits. Poke a few targets that give you 10 points (or are there any?) and see if it increases or stays at 00

.... back to you emulator guys....

Survey says...?

On my paragon, I only have one rollover that will register 50 points... anything else is 100 or more.
When I hit 50, it digit 2 goes 1,2,3,4,5.

If you don't have anything that registers 10 or 50 points on Harlem Globetrotters, then you may never see them shorted together, except for in the ball count (and maybe credit display).... does credit display count correctly?

In test mode, all 6 digits on display 5 are showing, even though only 3 are used in play mode... is that the same in yours?

I don't have any Ballys anymore to test on I think that's how it worked though

Clarification... question was really for Mark. I have a Paragon, which should have similar testing etc... as HG. On the HG, in test mode, do all 6 digits light up on display 5, like mine does on the Paragon? We're assuming yes, but photo could be interpreted otherwise.

Ah , OK. Yeah, that's definitely a question.

My bad... sorry man!

That Video isn't the display test, I wouldn't go off it. It seems like you're missing digits 4 and 6 in test? and if you connect the credit display connector to another display that is also missing those digits?

Assuming you mean there's no problem with the header pins on display 5. If the problem moves with the harness, then probably in the connector that goes on display 5. Pins 4 (first digit) and 6 (third digit).

If the problem was at the mpu end then it would affect all displays the same way.

Suspect you just have no connection on those if those digits never come in in test or play mode.

Note pins 2 and 3 on connector are not used. If you rebuilt the connector did you happen to pin pin 4 in slot 3?