ICs TL494 and KA7500 are equivalent. The letters of 494 can differ. Theese supplies use bipolar junction transistors (BJT) of NPN type.
SUNNY ATX-230 UC3843 TPS5510P.gif
SCHEMATIC OF AT 200W -W -TL494
OLD AT SMPS (VALUES MISSING)
DTK COMPUTER PTP-2007 MACRON