TV Philips 42PFL3606H/12 won't turn on

[Maximilius71]

Hi,

I've a TV Philips 42PFL3606H/12 (Chassis TPM6.1E) won't turn on; no led, no reaction from remote or keypad.

I unplugged the PSU (715G4802-P01-H20-003H) from the SSB and made the following actions:
All fuses are good.
No diodes are in sort-circuit.
On the CN903 connector, I only have + 5VSB and no + 12V or + 24V.
I connected the S / B pin to + 5V to get it out of sleep mode and still not + 12V or + 24V.
On the primary side, I only have + 325V instead of + 395V measured on C907 ?
On the other hand, the voltage Vdd-S is only + 5.25V; which is too weak ... I also untied pin 16 of IC801 (UBA2071AT) which could have been the cause of this collapse, but that did not change anything.

Do you have any suggestions for me?
Regards,
Maximilius

[William1967]

Re: TV Philips 42PFL3606H/12 won't turn on

On the primary side, I only have + 325V instead of + 395V measured on C907 ?

That is normal, the PFC isn't switched on. If there is a 5V available to the mainboard and there is no return signal to the power supply the power supply will stay in a kind of low power mode. You can try to make the power supply work by faking the power on signal from the mainboard.
If you ask me I think the mainboard is the problem.

[CapLeaker]

Re: TV Philips 42PFL3606H/12 won't turn on

So, the PSU is producing STBY voltage to the main board, but the main board is not doing anything. We need to see high resolution, straight shot pictures, so we can see details.
If the main board doesn't send PSon and BLon signals to the PSU, then the TV will remain off. You need a look at these signals on the connector that goes from the PSU to the main board first. IF you don't get PSon / BLon while you turning on the TV, the main board is the cause.

[Maximilius71]

Re: TV Philips 42PFL3606H/12 won't turn on

@ William1967, thanks for your reply.
I have indeed suspected the PFC circuit (IC902 = FAN6961SZ) to not work properly despite the setting to + 5V of the pin S/B. What are the signals (voltages) I need to find on this IC?
@CapLeaker, thanks for your answer.
I had also bridged the ENA (= BLON?) Pin from CN903 to + 5V but without success.
Regards

[CapLeaker]

Re: TV Philips 42PFL3606H/12 won't turn on

PSon turns on the voltage rails for the main board. BLon are the backlights. Both signals need to be present in order for the PSU to be fully on.

However: You need to verify the main board gets stby voltage. Then find the PSon and BLon, turn the TV on and measure the DCV on those pins. If there is no PSon sent from the main board, while it does get 5V STBY voltage, then the main board is bad.

SB is PSon, ENA is BLon you have to tie that through a 1k or so resistor to 5VSB. No main board connected. Plug the TV in, all the voltage rails should be on and the backlight on.

[Maximilius71]

Re: TV Philips 42PFL3606H/12 won't turn on

Dear CapLeaker,
I followed your suggestion by putting the ENA (BLon) and S/B (PSon) pins at +5V across a 1k resistor (one per pin) and the both voltages (+12V and +24V) are still 0V. The Backlight does not turn on.
I see my voltage Vdd-S go from +0.35V to +5.2V; that's all...
Regards,
Maximilius

[CapLeaker]

Re: TV Philips 42PFL3606H/12 won't turn on

Check if the PFC is working or not. No PFC = no 12 and 24V. You need close to 400V on the main filter capacitor. IC902 (FAN6961) is the PFC controller IC.