I’m looking for some advice with a Macintosh Plus

Hi everyone, I’m looking for some advice with a Macintosh Plus.

The machine works perfectly once it starts. It boots normally, the screen is stable, the floppy drive works, and it can stay powered on for hours without any problem.

The strange issue appears after shutdown: once I switch it off, it usually will not power on again. There is no chime, no CRT activity, nothing. I then have to leave it switched off for a very long time — sometimes several days — before it will start normally again.

The analog board is a 630-0108. Some damaged traces on the power-supply section have already been repaired, the large primary capacitors have been replaced, and a faulty high-voltage/power transistor was also replaced.

Has anyone seen this exact behaviour before? I’m especially wondering about a startup/reset circuit issue, a small electrolytic capacitor, a high-value startup resistor, or another component that prevents the PSU from restarting after shutdown.

Any ideas or known weak points on the 630-0108 analog board would be greatly appreciated. Thanks!