Bally Pool Sharks (Bally, 1990) Display Problem. D and F segments constantly lit. Please help

[stotzbotz]

Hello freinds. Just wondering if anyone would know why my left
display on my Bally Pool Sharks wants to light up more of the display
segments than it is supposed to. I recently purchased and replaced the
ribbon
cable that connects the left and right display board to the cpu. I
also replaced
the chip directly under the battery compartment that controls the
display as well as the 4 4001 ics on the display board with no
change.
I've cleaned the main board, looked for bad solder joints and bad
connections. The bottom segments as well as the top left segment on
every digit is lit and constant. I'd post an image if I knew how but
can send one if you like to see what I mean.I sure would greatly
appreciate any help. Many thanks in advance.
<WBR>

 

[spalmer]

Sorry I have not gotten back to you. I was dealing with some health issues and in the Hospital. If the 4001 IC's did not fix the issue, it could be a problem with the Hex buffers cuasing locked on segments. See the attached trouble shooting steps. If you would like, PM me your phone number and I can walk you through it. Make sure to do this with the machine off.

14049 Partial Segment Failures on Score Displays.​

Sometimes only parts of a display aren't displaying or are locked-on, and only on certain
numbers. For example, the top part of a "0" or "7" are not displaying or are always lockedon.
It can even be so strange so that the missing segment will work on some numbers or
letter, but not on others.
This can be caused by one of the hex input buffer 14049 or 4049 chips at U10, U11, U15-
U18 or U7-U9,U10-U11 on 16 character display boards. Note on the schematics sometimes
these are mis-labeled as 4050 chips! But these 4049 chips are CMOS and very static
sensitive. You can check these with your DMM set to diode test:
Red DMM lead to 4049 chip ground pin 8.
Use black DMM lead and probe pins 2-7, 9-12, 14-15 of each 4049 chip.
A reading of .6 to .7 should be seen. Any reading below this indicates a problem with​

the chip.