Re: LCD Philips 47PFL4606H/12 - power supply doesn't start, no voltages
The voltage on C907 will only be 313 volts because the pfc boost circuit is not working. And it won't operate untill you get the standby circuit working. You need to have (maybe 25 volts) across C946 to have ic905 working.
This is where a scope works really well, but without it... we must assume ic905 is trying to start and ouputing pulses on the drain (pin6)
If it is, there should be a HF a/c voltage on pin #4 of T904, If R959, D916 & C946 are ok there should be about 25 volts on C946.
Have you tried replacing C946 & C943?
It seems like there should be an initial voltage that comes via C910, R967, D904, through zd912, R951, zd908, R922, based on the ic's pdf, this voltage needs to be at least 6 volts before the ic even starts
I would check all the zener diodes in that circuit and even the resistors.
Before ic901 and ic902 can operate they need VCC, The source of the vcc (Vdd-S) is via switch Q907 collector and the source voltage for Q907 emitter is from C946.
The voltage on C907 will only be 313 volts because the pfc boost circuit is not working. And it won't operate untill you get the standby circuit working. You need to have (maybe 25 volts) across C946 to have ic905 working.
This is where a scope works really well, but without it... we must assume ic905 is trying to start and ouputing pulses on the drain (pin6)
If it is, there should be a HF a/c voltage on pin #4 of T904, If R959, D916 & C946 are ok there should be about 25 volts on C946.
Have you tried replacing C946 & C943?
It seems like there should be an initial voltage that comes via C910, R967, D904, through zd912, R951, zd908, R922, based on the ic's pdf, this voltage needs to be at least 6 volts before the ic even starts
I would check all the zener diodes in that circuit and even the resistors.
Before ic901 and ic902 can operate they need VCC, The source of the vcc (Vdd-S) is via switch Q907 collector and the source voltage for Q907 emitter is from C946.
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