Delphius wrote on 2023-11-05, 17:42:
Almost like there is a data line that is bridged with it. I have been testing short circuit from that pin but all that I can find it connecting to is U5 pin 9. There must be something I am missing or not understanding.
[...] I have checked all my work over a few times under the microscope and everything looks good as far as I can tell.
Bridges actually can hide quite well near the package under a TSSOPs (not applicable here) and aren't completely impossible under the SOICs also... if you're probing and seeing real signal activity (and not just noise) on the isolated RESET line, there really isn't many places where it could pick that up: it's indeed routed from the ISA slot (backside of the card, pad 2 on the ISA connector), directly to U5, pin 9:
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If it'd be caused by a bridge, you could look at U5, pin 10 and see if it's what you're seeing on pin 9 (or simply if those two are bridged):
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There also is a chance of a wrong IC in position U5 (only mentioning this, because something similar has happened before 😉. It should be a 74LVC14 in that place and a 74LVC00 at U6.
There's maybe one more thing you could verify: check if there's no bridges / connections / jumpers on the header footprint right at the ISA slot:
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If the signal activity is on the RUN side of things, then U6, pin 12 & 13 might be worth a look also.
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