Sony S75F Service Manual page 44

No Backlight
Check VDDA,ENA
VDDA=4.75~5.25V;ENA>3V
Preset at 2V to SST(pin4) of IC801 and
Connect CTIMR(Pin1) to GND
Check REF (pin7), RT (pin17), CT(pin18),NDRV_D(pin11),
PDRV C(pin12),PDRV A(pin19),NDRV B(pin20) of IC801
Check full bridge power conversion
circuit and Transformer output circuit
Check FB(pin9) of IC801 and Protection loop
debug and connect b pin of Q802,Q803 to GND
OK
Check FB circuit form lamp's return
to FB(pin9) of IC801
OK
OK
OK
OK
Check OVP(pin2) normally
NG
OK
End Striking function
Judge FB=0
NG
Check On/Off loop Circuit
NG
Check OVP loop
NG
Normal condition Check b pin
voltage of Q802,Q803<0V
End FB circuit and
Protection loop
44
S75F Sony
Change IC801
Check Protection
circuit, Components
short, open or fail
NG
OK