[vcf-midatlantic] PC/AT power-good troubleshooting

Richard Cini rich.cini at verizon.net
Sat May 28 14:16:05 EDT 2016

All –


                I pulled my old PC/AT off the shelf to see if I could get Windows 1 running on it. It worked when shelved years ago, but it unfortunately suffered some case damage from a leaky battery. No damage to the mobo or cards thankfully. I replaced the battery with a 4-AA pack.


Basically, the PC won’t come out of reset. I tested the power supply with a load tester specifically for PC power supplies and it reports power_good and all voltages look good on a meter. So far, so good. I dug out my ISA POST diagnostics card which also has a PG tester in it. This reports no_PG but I do see the reset pulse. Not sure why one would report OK and one not.


I traced the PG signal from the power supply through the 82284 clock driver/ready interface chip and the PG is definitely there (transitioning L->H on power-on) and RESET is transitioning H->L. 


                I have a spare power supply (which also tests good) and produces the same result. I have no cards installed, nor any other load on the supply (floppy and hard drives disconnected), so it purely has to be an issue with the motherboard. 


                Any recommendations on where to go from here? Does anyone have an extra AT motherboard they would be willing to part with?







Rich Cini



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