Quoted from balzofsteel:Turn the game off when unplugging boards and measuring resistance. Test resistors with the meter set to Ω . Put the leads on either end and see what you get. The number you get can be affected by other devices in parallel with the part being tested.
4543 decoder chips here: https://www.greatplainselectronics.com/products.asp?cat=11&pg=3
Put it in a socket. I like the SIP strips at the top of the page - they snap to length to fit any chip. : https://www.greatplainselectronics.com/products.asp?cat=161
While you're at it, get some 1/2 watt 100KΩ resistors and replace R26, R30, R32, R33, R34, R39, and R44 on all four player displays as well as R1, R3, R5, R7, R9, and R11 on the credit/match board. Might as well if they're out getting header pins soldered. https://www.greatplainselectronics.com/RCF_Half.asp
I don't think you need to go out of your way to change the 100k resistors in the digit drive to 1/2w. In my XP they only fail when there is some other problem that makes them fail, like a locked digit driver.
For the OP issue with missing segment.... Replace segment 'f' driver at Q18. Still no go, replace the 7 segment decoder IC 4543. Still no go, follow the segment circuit up to where it goes into the glass. Compare to other segments in display test with DMM. If good there, the display is bad itself.
Crown Point, IN
