o.k. the problem is at the very start of the por circuit,
before entering pin3 of F7
normally pin3 of F7 should be high, only going low to do a reset.
not much to cause this, just diode cr3(1N914/1N4148) and R8 (TLO82)
as a test, remove one end of cr3,
then lift the end of R71 that goes to pin1 of the chip and connect it to pin2.
that will isolate the por and give you a 1k pullup on the reset line.
then you can reset the system with the reset pins and watch what happens to the reset pin at the cpu.
this should either start the game or if there is more problems it should make the reset-pin pulse at the cpu.
if it does then replace the chip(tlo82) and the diode.
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Received on Sat Aug 6 22:42:11 2005
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