Phillips 42PFL3704D/F7 no video

[itrcomp]

I have a 42PFL3704D/F7 that will turn on and off but there is no video\backlight at all. I have read all posts related to this model. I have downloaded schematics and all voltages seem to be accurate with whats posted on schematics. I have pulled all caps on inverter and verified, checked 2 fuses and reflowed all connections on transformers/coils on inverter. I get 24v @ inverter connections. Could this be a T-con issue or the board after the t-con. I do not believe it is the power supply or main board but could be wrong? Any suggestions?

[JonathanAnon]

Re: Phillips 42PFL3704D/F7 no video

I have a 42PFL3704D/F7 that will turn on and off but there is no video\backlight at all.

When you say it "will turn on and off", do you mean that you can hear audio? or can you see the outline of the image on the screen using a torch? If there is stable 24V on the inverter rails then the backlight should be coming on. Is it backlight coming on and then shutting down, or just not coming on at all?

Can you post pictures of the relevant boards, back and front.. A video of the fault might also be of use.

[budm]

Re: Phillips 42PFL3704D/F7 no video

Yes, good pictures of all the boards. The inverter board is getting 24Vdc feeding it, but it will not turn on the backlights until it gets the BL_ON (or INV_ON, or ON/OFF) signal from the main board.

[itrcomp]

Re: Phillips 42PFL3704D/F7 no video

I will take pictures and post. There is no video at all, using flashlight in dark room there is nothing on screen. I can turn on, i hear a click and white power light. Pics have been added to original post, Thank You

[oleg_yj]

Re: Phillips 42PFL3704D/F7 no video

There is selfrecoverig fuse on the invertor board.Don't remember location.Strait after power connector.It's smd,black and looks like diod.Check it with ommeter.

[itrcomp]

Re: Phillips 42PFL3704D/F7 no video

I have tried those fuses already, Thanks

[JonathanAnon]

Re: Phillips 42PFL3704D/F7 no video

Like Bud says above, the power board needs to get a BL_ON signal and INV_ON signal (which is passed from the main board) for the inverter to come on... But we need more information to help you... A video of what the TV is doing would be very helpful, along with pictures of the boards (back and front)

[tom66]

Re: Phillips 42PFL3704D/F7 no video

BL_ON == INV_ON
Do you mean PSON?

[JonathanAnon]

Re: Phillips 42PFL3704D/F7 no video

BL_ON == INV_ON .. Do you mean PSON?

You know, it kind of felt strange even when I was writing it ..
Yep, that's what I meant.. I'd never even used the INV_ON term until I watched this video on youtube..

http://www.youtube.com/watch?v=j7O2sKD67Cw

it's quite good but the audio outages are slightly annoying,.

[budm]

Re: Phillips 42PFL3704D/F7 no video

How many fuses on the board did you check? Do they have 24VDC on both ends?

[oleg_yj]

Re: Phillips 42PFL3704D/F7 no video

Sorry, didn't understand which fuses you check.
If you have 24V to invertor, do you have BL-ON to invertor too?
Can you take detail picture between power connectors there're more components?

[budm]

Re: Phillips 42PFL3704D/F7 no video

You need to check the fuse as circled, and the DC voltage on that ON/OFF (same as BL_ON, or INV_ON) pin.

[itrcomp]

Re: Phillips 42PFL3704D/F7 no video

Thanks Budm, I was only checking the 2 white fuses on inverter board. I completely overlooked the little black fuse, It was bad. No the million dollar question is does any body now the value off hand

[tom66]

Re: Phillips 42PFL3704D/F7 no video

It's written next to it. 0.75A/76V. As it operates on a 24V circuit any fuse rated more than about 24V will be fine.

[itrcomp]

Re: Phillips 42PFL3704D/F7 no video

thanks Tom, wasn't sure if that value was for the white or black fuse

[tom66]

Re: Phillips 42PFL3704D/F7 no video

The white fuse carries the main backlight current, 8A at 24V, the black fuse is for the low power control circuit.

[budm]

Re: Phillips 42PFL3704D/F7 no video

I used PICO II fuse 1A for my repair.

[itrcomp]

Re: Phillips 42PFL3704D/F7 no video

Thanks all for the help!!!!!

[gerstoscar]

Re: Phillips 42PFL3704D/F7 no video

You need to check the fuse as circled, and the DC voltage on that ON/OFF (same as BL_ON, or INV_ON) pin.

I'm trying to test this fuse, how should i test it... where should i position the positive and negative leads of the multimeter? if i check the fuse of the black one just show OL. Does it mean is a bad fuse or am i making things wrong? Sorry im a newbie...but learning on the run...Please a little help would be appreciated.

[DeanAllen85]

Re: Phillips 42PFL3704D/F7 no video

I have a 42PFL3704D/F7 that will turn on and off but there is no video\backlight at all. I have read all posts related to this model. I have downloaded schematics and all voltages seem to be accurate with whats posted on schematics. I have pulled all caps on inverter and verified, checked 2 fuses and reflowed all connections on transformers/coils on inverter. I get 24v @ inverter connections. Could this be a T-con issue or the board after the t-con. I do not believe it is the power supply or main board but could be wrong? Any suggestions?

Are you getting any standby light?