always take voltage measurements at the pcb, while it is plugged in and powered on. The roms, cpu, logic etc chips themselves want 5.0000000v on their 5v lines. Most chips are not very tolerant, meaning they don’t operate properly even at +/- 5% (so below 4.75v or above 5.25v). I consider the whole 5v rail 1% tolerant, so you want the whole thing between 4.95 and 5.05. The jamma edge is an ok proxy if you’re only measuring in one place. Measure voltage at the jamma edge and adjust the psu so the edge reads 5.00. Maybe a tiny bit higher since there is drop off from the edge to the other side of the pcb. But like 5.02 should be fine. (Unless it’s a gigantic and old board stack…)
The psu doesn’t care, don’t measure there. It’s adjustable for this very reason.
12v doesn’t matter as much because it only drives audio, usually the amp, and those chips are considerably more tolerant. I’ve seen spec sheets on audio amps that say they’ll run between 6v and 18v for example.
The psu doesn’t care, don’t measure there. It’s adjustable for this very reason.
12v doesn’t matter as much because it only drives audio, usually the amp, and those chips are considerably more tolerant. I’ve seen spec sheets on audio amps that say they’ll run between 6v and 18v for example.
