[charlie_ps2]

... and is it, say, 20 mins then switches off or 3 mins?

Is the fan running?

Is the heat conducting pad present on the BA58 chip?

Is the heat conduct pad setup present on the metal cage above the EE chip?

Is the metal cage fully screwed down and the plastic cover on top of that?

If the PS2 is overheating, usually the red light will blink when it switches off.