Trying to get my Cue Ball Wizard up and running. I have some display issues I have posted in another thread. I'm not sure if just my display board is out or if both my CPU and my display boards are out. Its my understanding the CPU will not boot if the display controller board is out(not working)?
I'm trying to learn how to read schematics and work through these boards.
Here's what happened:
I was using my logic probe to test pin 40 on U1 of the cpu because my light is flickering with intermittent stops. I read in another post that this would indicate a bad watch dog circuit. While in the process I shorted pins 39 and 40 and the CPU instantly booted up and the game went into attract mode. I actually did this a couple times and it's consistent.
I began reading the schematic to try to determine why shorting these two pins would make this occur. According to the picture of the schematic attached should pin 39 be 5 volts? When tested I am only getting 2.4 volts. Could it be that the U1 chip is bad if pin 39 is not 5 volts? My thinking is maybe when it is given the extra voltage it is allowing the cpu to boot. Also, Should pin 39 be 5 volts if pin 38 is 5 volts, plus R4 is showing 5 volts? When I check voltage at R4 I'm getting 2.4 volts on one side and 5v on the other. Hopefully I haven't confused anyone. Thanks so much for any help!!!
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