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Old 02 July 2020, 16:01   #4
bwldrbst
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Join Date: Nov 2015
Location: Perth, Australia
Posts: 56
I've measured the voltage at the PSU motherboard connector with a floppy drive, scsi2sd and cdrom connected. 5V lines register ~4.9 volts, +12V reads as 11.6 and -12V reads as -11.3.

Are these reasonable or is it meaningless without more load?

I also measured the 5V and 12V, pins 12 and 23, of the external floppy connector. 12V was 11.6 but there was nothing on the 5V pin. I guess that explains the external floppy not working.

Having a look at the schematic, it seems I should be able to measure connectivity between that pin and EMI321 but there's none. Cracked solder join perhaps?

I measured pin 14 of the parallel port and it showed 4.8V or so. Maybe one of the other pins is suffering the same problem?

Pin 12 should be connected to EMI337 and 13 to EMI338 but there's no connectivity. Could be my problem?

A spare parts motherboard I have shows connectivity on all those pins to the EMIxxx components.

Does this sound like reasonable troubleshooting? My plan now is to pull the motherboard out of the chassis and reflow the solder on those pins.

Any other suggestions?
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