FAN flow corrosion.
Int. print between PCB and ISA-connector (Flashed).
SMD: 2k2, 4148, ZD15V, UC3855.
SS-Resistor 33 Ohm 9W.
Tested. Wile test green and red LEDs flash shortly 10-20s
after this green stay on. Tested on real 230VAC after safe testing 
with isolated 230VAC input.