Just spent days troubleshooting a PFC board out of a California Instruments P1001 inverter. Come to find out, the previous repair replaced the UC3854 with a UC3854A (datasheet says it is pin-pin compatible better replacement). But the AN also says that the voltage feedback resistor needs changed to accommodate a lower Vref, which wasn't done... so output voltage was not limited, and this damaged a slew of things.
