Hello I have a Topward TPS 4000 power supply and the Master output is not working....No voltage output. I have read that the pass transistor die on the quite often. Are the pass transistors mounts on the heating on the back of the unit? Since this is the American Reliance branded PS-4330 the schematics are lacking. Has anybody had the opportunity to repair one of these lately.Any help would be appreciated; thanks.