Philips 55PFL5705D/F7 Not Powering Up

[newman25]

Hello everyone,

I have a Philips 55PFL5705D/F7 TV and I just am getting a flashing light when the set is powered on. I have opened it up and did some testing on the power board and I think I have found some oddity but I'm not sure if it is normal. I have no flashing light until I press the power button. I don't hear any clicks either when pressed. Below are the voltages that I measured while off and with the power button pressed.

I have the following plugs. Listed are:

CN2 (Power supply to Main Board) The first two readings are with the cable connected to the main board and the last is with it disconnected.

Pin Desc Voltage(w/o pwr btn) Voltage(w/pwr btn) Voltage (unplgd)
1 12.5v 0v 12.43v 0v
2 12.5v 0v 12.43v 0v
3 12.5v 0v 12.43v 0v
4 12.5v 0v 12.43v 0v
5 Gnd
6 Gnd
7 Gnd
8 Gnd
9 5.3v 0v 5.35v 0v
10 BL_Adj2
11 Gnd 0v 0v -6.19v(?)
12 PSON 0v 3.09v 0v
13 BL_Adj1
14 BL_SW

CN4

Pin Desc Voltage(w/o pwr btn) Voltage(w/pwr btn)
1 24v 0v 25.47v
2 24v 0v 25.47v
3 24v 0v 25.47v
4 24v 0v 25.47v
5 24v 0v 25.47v
6 Gnd
7 Gnd
8 Gnd
9 Gnd
10 Gnd
11 Protect3 0v 0v
12 BL_SW 0v 0v
13 BL_ADJ1 0v 0v
14 BL_ADJ2 0v 0v

CN5

Pin Desc Voltage(w/o pwr btn) Voltage(w/pwr btn)
1 24v 0v 25.47v
2 24v 0v 25.47v
3 24v 0v 25.47v
4 24v 0v 25.47v
5 24v 0v 25.47v
6 GND
7 GND
8 GND
9 GND
10 GND

I want to try and power on the power supply and the backlight without it connected to the main board but I can't figure out what pins to connect since I am getting the odd reading(-6.19v) when I unplug the cable from the main board. I'm kind of suspecting the main board since I get the proper power readings when I power on the TV with the cables connected but I am not sure.

I think I am now lost and I think I need to be pointed in the right direction....

I attached some photos of the power board, pin headers, etc.

Thanks for your help.
Brian

[CapLeaker]

Re: Philips 55PFL5705D/F7 Not Powering Up

First thing that I notice is that you don't get any back light signal (BL_SW) from the main board. There are no voltages given at CN2 and on CN4 it is 0 Volts.

In order to force on the PSU with the back lights, you need a few 1K Ohm resistors. Jump STBY voltage to PSon and another one from STBY to BL_SW. Plug it in and the back lights should be on and all the voltage rails on the PSU.
If the backlights are still not on, you may need to do the same trick to the BL ADJ pins.

[budm]

Re: Philips 55PFL5705D/F7 Not Powering Up

Please add that you have to disconnect the cable going back to the main board first before forcing on the power supply board.

[newman25]

Re: Philips 55PFL5705D/F7 Not Powering Up

First thing that I notice is that you don't get any back light signal (BL_SW) from the main board. There are no voltages given at CN2 and on CN4 it is 0 Volts.

I measured BL_SW on CN2 and it is 0v as well, I forgot to add that to the above measurements.

I will try jumping STBY to PSON and STBY to BL_SW and see what I get.

When I have the connector between the PSU and the main board disconnected I do not have a pin with voltage as some of the videos that I watched do. What I do have is a Gnd(pin11) with -6.19v on it. Is this something that I should be concerned with?

Should I have 5.3v on pin 9 without the connector attached?

The voltages that I measured above are with the connector between the PSU and the motherboard connected and after pressing the power button on the TV.

[budm]

Re: Philips 55PFL5705D/F7 Not Powering Up

Do not try to force on the board without disconnecting the cable to the main board first.

[newman25]

Re: Philips 55PFL5705D/F7 Not Powering Up

I have not tried to force it yet. I'm concerned that I do not have a STBY voltage and a negative voltage on a GND pin.

[CapLeaker]

Re: Philips 55PFL5705D/F7 Not Powering Up

Use the other GND pin like 5, 6, 7 or 8. The idea right now is to fire the whole PSU up, in order to see what it does without the main board attached.
check if GND pins mentioned above is connected to GND pin 11.

[newman25]

Re: Philips 55PFL5705D/F7 Not Powering Up

Use the other GND pin like 5, 6, 7 or 8. The idea right now is to fire the whole PSU up, in order to see what it does without the main board attached.
check if GND pins mentioned above is connected to GND pin 11.

I have continuity between the pin(11) with the -6.19v and all the other pins(1-14,13 is empty). That doesn't seem right??

[newman25]

Re: Philips 55PFL5705D/F7 Not Powering Up

I have continuity between the pin(11) with the -6.19v and all the other pins(1-14,13 is empty). That doesn't seem right??

Sorry, let me clarify... I have continuity as described above when the power plug is connected. Without the power plug connected, I do not have continuity between them all. The GND pins at 5,6,7,8 all have continuity and there is none between pin 11 and 5,6,7,8.

Also, since I do not have any standby voltage on any pin, will I be able to force the PSU on?

[CapLeaker]

Re: Philips 55PFL5705D/F7 Not Powering Up

That doesn't make any sense. Oh wait... I know what's going on. Plug the PSU in by itself, nothing hooked up and measure the voltage between GND and PSon. I bet there is voltage there. If that is the case, take a 100 Ohm or so resistor and jump that to GND. Then one the voltage rails fire up, then measure the BL_SW. If that has no voltage on it, jump a 1k resistor between 5V and BL_SW and hook up the back lights. Plug it in and see what happens.

[Diah]

Re: Philips 55PFL5705D/F7 Not Powering Up

Sorry, let me clarify...

Philips PFL series had self SERVICE DEFAULT MODE called SDM and its remarked on the Main AV Board, with 2 points to short them or if one point to sort it to GND and turn on TV do this first and tell result what you have

[newman25]

Re: Philips 55PFL5705D/F7 Not Powering Up

I've been out of town for work the past week and half....

I decided to check out all the diodes to make sure they were good and found that ZD951 was shorted D950 and D951 read low so I replaced them. I must have blown them while testing...I'm not sure. After replacing them I now have stby voltage again but it is 9.9v. Did I blow out a voltage regulator as well?

So when I was searching for the diode in D950 and D951 (SB260) I came across this thread on here and replaced the 2 diodes in parallel with a single larger SB5100 diode. I also seem to have the identical problem.

I do not have any voltage on BL_SW and the backlight does not turn on. I jumped the 5.3v to BL_SW and the backlights came on. According to CapLeaker in that thread the BL voltage comes from IC3101 which seems to be the main IC on that board so I will need to be on the lookout for a replacement.

The main board that is in this set looks identical to the board for the 46" and the 40" mainboards. I attached pictures of my main board.

Do these boards just have different firmware? I haven't seen many parts for the 55" tv out on ebay but I do see main boards have popped up for the 46"and 40" tvs. Do you think one of those boards would work?

[newman25]

Re: Philips 55PFL5705D/F7 Not Powering Up

Philips PFL series had self SERVICE DEFAULT MODE called SDM and its remarked on the Main AV Board, with 2 points to short them or if one point to sort it to GND and turn on TV do this first and tell result what you have

I do not see anything marked like that on this main board. I looked on both sides but I assume it would be on the main component side right?

[newman25]

Re: Philips 55PFL5705D/F7 Not Powering Up

Does anybody know if I can use this board in the 55?

http://www.ebay.com/itm/361564139824...%3AMEBIDX%3AIT

The board numbers are the same, maybe a different revision but would it work or does there need to be specific firmware for the size? I've read that it may be possible if I have the Screen Diversity Codes and Option Codes?

Do I give this board a shot or should I hold out and be hopeful one for this TV will show up?

[dick_barton]

Re: Philips 55PFL5705D/F7 Not Powering Up

Try an get an identical replacement because firmware take make and model of screen into account. Shopjimmy may have a list of mainboards you can use with your set. I understand they are extremely helpful although I have never used them.