Philips 55PFL3907/F7 Dead, No Standby LED, Nothing, Please Help

[sfernandes]

When plugged in to the mains I hear the relay click and that is all, no standby LED, no response from power button or remote.

Can't find a power supply for this one anywhere as everywhere it's sold out even eBay does't have one, so I have to try and repair this one if it indeed the power supply.

I have attached a picture of the power supply

anyone know what I should check?

no caps are bulged

The only voltage i could get is 4.3 Volts on the pin that says ALL which is pin 6

everything else is dead on the connectors

Any Ideas?

[Moreno83]

Re: Philips 55PFL3907/F7 Dead, No Standby LED, Nothing, Please Help

It sounds like your mainboard is dead. Any more information about this tv?

Is there any voltage going in to the mainboard? Meter in dc voltage and check the connector on the mainboard ( That comes from the PS ).

Led signal/power button etc is controlled by the mainboard.

[sfernandes]

Re: Philips 55PFL3907/F7 Dead, No Standby LED, Nothing, Please Help

It sounds like your mainboard is dead. Any more information about this tv?

Is there any voltage going in to the mainboard? Meter in dc voltage and check the connector on the mainboard ( That comes from the PS ).

Led signal/power button etc is controlled by the mainboard.

the connector on the main shows the same 4.3 voltage on the same connector from the ALL pin on the PS.

[sfernandes]

Re: Philips 55PFL3907/F7 Dead, No Standby LED, Nothing, Please Help

Anyone?

[R_J]

Re: Philips 55PFL3907/F7 Dead, No Standby LED, Nothing, Please Help

disconect the power supply CN801, then connect about a 1K resistor between ALL +4.3V and P-ON-H2, (on the power board) see if you get your +12 & inverter +24 (backlight might even light)
I see shopjimmy lists a repair kit for this board with about 35 parts

[Dannyx]

Re: Philips 55PFL3907/F7 Dead, No Standby LED, Nothing, Please Help

Try turning on the PSU on its own like the last guy suggested: connect the only voltage source, that "ALL" pin to ON H2 pin 3 and see if the other rails come on. If not, I suggest checking the diodes - those large DO-201 diodes (D1735 thru D1738) after the switching transformer are usually the prime suspects when a PSU appears dead but the fuse is fine.

[Moreno83]

Re: Philips 55PFL3907/F7 Dead, No Standby LED, Nothing, Please Help

With a dead powersupply there would be a good chance there is LED blinking. He has 4+ v going to mainboard , what happened with the voltage that controls the leds?

[thoma]

Re: Philips 55PFL3907/F7 Dead, No Standby LED, Nothing, Please Help

https://www.electronica-pt.com/esque...-pl11.9-26605/

schematic for this Philips LCD Chassis PL11.9

[sfernandes]

Re: Philips 55PFL3907/F7 Dead, No Standby LED, Nothing, Please Help

Try turning on the PSU on its own like the last guy suggested: connect the only voltage source, that "ALL" pin to ON H2 pin 3 and see if the other rails come on. If not, I suggest checking the diodes - those large DO-201 diodes (D1735 thru D1738) after the switching transformer are usually the prime suspects when a PSU appears dead but the fuse is fine.

I'll try that, but I have checked those diodes and they appear fine. I checked them in circuit is that ok? they tested all the same readings. to force the ps on do I have to use a resistor like the guy above suggested or could I just use a jumper wire instead?

[sfernandes]

Re: Philips 55PFL3907/F7 Dead, No Standby LED, Nothing, Please Help

disconect the power supply CN801, then connect about a 1K resistor between ALL +4.3V and P-ON-H2, (on the power board) see if you get your +12 & inverter +24 (backlight might even light)
I see shopjimmy lists a repair kit for this board with about 35 parts

I'll try this, but do I have to use a resistor or could I just use a jumper wire instead? please advise

[sfernandes]

Re: Philips 55PFL3907/F7 Dead, No Standby LED, Nothing, Please Help

With a dead powersupply there would be a good chance there is LED blinking. He has 4+ v going to mainboard , what happened with the voltage that controls the leds?

there is no other voltages other than the 4+, there is no LED voltage its at 0.

[sfernandes]

Re: Philips 55PFL3907/F7 Dead, No Standby LED, Nothing, Please Help

https://www.electronica-pt.com/esque...-pl11.9-26605/

schematic for this Philips LCD Chassis PL11.9

thanks I already have found it. according to the troubleshooting flow chart its saying the ps is at fault for a dead condition.

[dick_barton]

Re: Philips 55PFL3907/F7 Dead, No Standby LED, Nothing, Please Help

Pin 6 of connector CN3101 as shown in the schematic attached above should be at 5V (AL+5V) so 4.3V is low and I would look to see why.

[Dannyx]

Re: Philips 55PFL3907/F7 Dead, No Standby LED, Nothing, Please Help

I'll try that, but I have checked those diodes and they appear fine. I checked them in circuit is that ok? they tested all the same readings. to force the ps on do I have to use a resistor like the guy above suggested or could I just use a jumper wire instead?

Yes, testing diodes in circuit is possible (I do it all the time): since diodes fail shorted, the meter should beep when in continuity mode if the diode is faulty. If it doesn't beep, the diode is most likely fine.

I like to use a small value resistor between the standby rail and the PS_ON pin when "tricking" PSUs into turning on like this, just to be on the safe side, although it COULD be done directly (I did it a lot before learning about the resistor and never had any damage).

[Moreno83]

Re: Philips 55PFL3907/F7 Dead, No Standby LED, Nothing, Please Help

That could be his meter. I think +/- 5v goes into mainboard , mainboard turns on the rest of the tv. He has no standby led so i still think mainboard is bad.

If mainboard is ok he should still be able to use the powerbutton?

[sfernandes]

Re: Philips 55PFL3907/F7 Dead, No Standby LED, Nothing, Please Help

Yes, testing diodes in circuit is possible (I do it all the time): since diodes fail shorted, the meter should beep when in continuity mode if the diode is faulty. If it doesn't beep, the diode is most likely fine.

I like to use a small value resistor between the standby rail and the PS_ON pin when "tricking" PSUs into turning on like this, just to be on the safe side, although it COULD be done directly (I did it a lot before learning about the resistor and never had any damage).

Thats how I tested all diodes and they all test fine. i'm going to try this and report my findings back. if I get the ps to turn on by jumping it this way that means its a mainboard fault correct?

[Dannyx]

Re: Philips 55PFL3907/F7 Dead, No Standby LED, Nothing, Please Help

Ok i'm going to try this and report my findings back. if I get the ps to turn on by jumping it this way that means its a mainboard fault correct?

Yes, correct....I too begin to think it's a MB fault....

[sfernandes]

Re: Philips 55PFL3907/F7 Dead, No Standby LED, Nothing, Please Help

Yes, correct....I too begin to think it's a MB fault....

could be, i will let you all know. thanks guys

[sfernandes]

Re: Philips 55PFL3907/F7 Dead, No Standby LED, Nothing, Please Help

well guys I just tried this now as I have been away and the backlights do not come on, but the other rails do have voltage when I jump it, the backlights have 3. something etc the 12volt is showing a reading, but much lower than 12volts so I don't know what to think now any ideas? I do not see any 24volts from backlights not sure what pin that's supposed to be on because all the backlights are 3. something volts they measure at. how should I proceed?

[sfernandes]

Re: Philips 55PFL3907/F7 Dead, No Standby LED, Nothing, Please Help

Ok well I did more intelligent testing looking at the service manual and this is what I get with forcing the power supply on by jumping it. Keep in mind without forcing the power supply on all these rails are dead. Nothing is plugged into the PS during these measurements, its just the ps on it's own with everything disconnected from it. How should I proceed? Please help.

CN1801

- Pins 1 to 5 should be 12 Volts, but I'm only getting 1.734 Volts.

CN1913

- Pins 1 to 5 should be 24 Volts, but I'm only getting 5.126 Volts.

CN1914

- Pins 1 to 5 should be 24 Volts, but I'm only getting 5.126 Volts.