Is Power getting Past the Battery Holder?
(bad diode D2 or RAM U8) If the battery holder is OK, next check to see if power it getting past the battery holder. Find CPU board diode D2 (1n4148, all WPC revisions); this is a small glass diode, right next to diode D1 (1n5817). To find D2, on WPC-S and prior, look to the right of the big square chip U9. On WPC-95, look just below the battery holder. With your game off and new batteries installed, put your DDM on DC volts and put the black lead on the backbox ground strap. Then put the red lead on diode D2 on the CPU board. The banded side of the diode should show about 1/2 volts less than the non-banded side (which should be about 4.3 volts). If only one side of the diode shows voltage, or both sides show the same voltage, this diode D2 is bad. Diode D2 is a 1N4148 or 1N914 diode. The D2 can be replaced with a 1n4001 in a pinch (the 1n4148 or 1n914 is a ‘faster’ diode, but in this situation a 1n4001 will work fine.) Note that diode D1 is a 1n5817, which has a low .2 volt forward vo
