I know I'm an idiot. I installed a standard ATX power supply on an FM Towns HR. I read a few posts that said the brown cables are 5V/12V and -12V. And I knew which cable had which voltage. But because I was too confident and too quick, I didn't read any more while tinkering. And what had to happen happened: I swapped 5V and 12V. I'm such an idiot.
Something was sizzling on the front right. Now it won't turn on.
Has this ever happened to anyone and does anyone have any idea what could have gone wrong?
Although I just got the HR and don't know if it would have worked before. But 12V on the 5V line, something must have gone wrong.
After swapping the 5V/12V, my PSU works in another FM Towns Fresh (MA).
I was hoping to at least be able to use the HR CD-ROM, since the MA one is completely broken, but it doesn't read discs either.
It's a shame there's no ODE for the desktop. The wizard in the Grey Tower works very well.
After striping the machine it seems the CPU itself to be broken. If not other chips. The 486SX is getting very Hot.
I feel for you. I made a similar voltage mistake on a 386 laptop board I was trying to experiment with on a bench many years ago. This vintage of PC hardware is designed to put all of the voltage regulation on the power supply side, so there's hardly any safeguards once you get past those connectors. And it's really hard to know what components are damaged from too much voltage without pulling and testing each one individually.
I managed to install an MA motherboard (486SX33) into the HR case. The MA case is in terrible condition. And I prefer the gray HR case. Since I only have one running CD-ROM anyway, I opted for this solution.