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Hot take: I used a modern power supply on a 486 and it fried the motherboard
I thought the ATX to AT adapter would be fine, but the voltage regulation was too aggressive and it sent a surge. I learned the hard way that you really need a proper old PSU or a modern one specifically designed for vintage loads. Anyone know a good brand for a safe replacement that won't cost a fortune?
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johnfoster1mo ago
The voltage regulation theory is a common myth. Modern PSUs are actually more stable. The issue is usually the power good signal timing. An ATX supply sends that signal too fast for an old 486 board to handle, which causes a lockup or failure to post. You just need a proper delay circuit on the adapter.
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cole_bailey851mo ago
Wait, so you're saying the power good signal is the real culprit? How would I even test that on my fried board to confirm, or is it a lost cause now? I've seen a few delay circuit schematics online, but they all seem to assume the motherboard still works to begin with.
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Got a multimeter? You can check for voltage on the PWR_OK pin to see if it's sending signal too fast, even on a dead board.
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