I repaired two of these power supply recently. This supply actually has three inverters; one a pre-regulator, one for housekeeping, ie, low current for the front panel, etc, and the main one.
The chip that has exploded is an inverter chip, TOP244GN, is there a blown resistor on the bottom of the board?
The TOP 244 has a heatsink pad underneath, I used a hot air nozzle to remove.
What I did to fix the supply;
I removed the heatsink with the inverter transistors and carefully checked them on a curve tracer, one was bad.
I replaced that, the TOP244, the opto couplers, burned resistor on the bottom.
I also checked ALL the other diodes, resistors, etc.
I also replaced all the small electro caps.
Take your time, CHECK EVERYTHING, and you should be able to fix it. There are no replacements.