No backlight Philips 42pfl6007h/12 TV after thunderstorm

[Gjackson]

Hi, This post is a continuation of my previous post regarding another question about this tv. After getting struck by lightning my tv's backlight has stopped turning on, on powerup it turns on for a couple of milliseconds and then shuts off, I've tried forcing on the backlights and tested the mainboard which is working perfectly but the PSU shows no voltage output even when the backlight is disconnected leading me to believe that the PSU is almost certainly the problem. The PSU's model number is DPS-119CP (I've included an image below), I'm still unable to figure out whether this TV uses CFL or LED backlights (I would really appreciate it if you could help me figure that out). Any ideas of how I can proceed? As I would like to attempt to fix the PSU before completely replacing it. Thanks!

(The backlight connectors are the ones at the top right in the image - 2 connectors, one black, one white)

One other thing I forgot to mention, sometimes when plugging in the tv I see a spark happen a little above those 2 green coils that are located close to the fuse (between the top coil and that black cuboid capacitor). This doesn't always happen and I'm not sure which exact component is arcing

[Maalobs]

Re: No backlight Philips 42pfl6007h/12 TV after thunderstorm

You have a link to the service manual in the other thread.
Chapter 5 covers fault finding and you should study the chapter in detail, including the flowcharts.

The service manual covers a chassis that is used in several different TV-models, and consequently some sections describe model-specific information.
Use Table 2-1 to find out which sections are unique to your particular TV-model.
The table points to section 7-2 for a description of the power supply, and there is additional information there about testing and component-level repairs on the power supply.

Unfortunately there isn't a schematic provided for the power supply in your specific TV-model, though.

A tip:
You can open your images in MSPaint and add annotations into the bitmap to mark points of interest.

[Gjackson]

Re: No backlight Philips 42pfl6007h/12 TV after thunderstorm

Thanks for the info! I've had a look at the service manual however unfortunately the PSU that I have is stated as being a "Black box" with instructions stating that you should just replace the unit.

[lotas]

Re: No backlight Philips 42pfl6007h/12 TV after thunderstorm

Here is a diagram of the DPS-119AP A, but without the ratings.

[stj]

Re: No backlight Philips 42pfl6007h/12 TV after thunderstorm

look at the lamp transformer and any semiconductors connected to it.
coils make great EMP recievers during storms!

[Gjackson]

Re: No backlight Philips 42pfl6007h/12 TV after thunderstorm

So I searched around for a bit and found a diode ic that seems to have something to do with the backlights (image below), after testing with my multimeter I found it to be shorted as it lets current pass both ways, 0.1v one way and 0.3v the other way. I'll remove it from the Pcb and test it when it's out of circuit to see if its the problem

[Gjackson]

Re: No backlight Philips 42pfl6007h/12 TV after thunderstorm

Does anyone know how I can test if the transformer is good? I can't seem to found what pinouts it has. I believe these 2 are the backlight transformers, it seems to me that the larger one is the one that actually generates voltage for the connector on the PSU, any idea what the small one does?

Edit: I probed the large transformer's input (the 4 pins on the hot side) and they are all completely shorted, is this normal?

[lotas]

Re: No backlight Philips 42pfl6007h/12 TV after thunderstorm

I gave you a diagram

[sam_sam_sam]

Re: No backlight Philips 42pfl6007h/12 TV after thunderstorm

Does anyone know how I can test if the transformer is good? I can't seem to found what pinouts it has. I believe these 2 are the backlight transformers, it seems to me that the larger one is the one that actually generates voltage for the connector on the PSU, any idea what the small one does?

Edit: I probed the large transformer's input (the 4 pins on the hot side) and they are all completely shorted, is this normal?

You have to use a Ring Tester to check the transformer you can not use a ohm meter for the purpose of checking a transformer the only you can check for is an open winding

[Gjackson]

Re: No backlight Philips 42pfl6007h/12 TV after thunderstorm

Update:

I found 2 bad Fet's that control the backlight, after replacing it works perfectly now! Thank you all.

[jellekaz]

Re: No backlight Philips 42pfl6007h/12 TV after thunderstorm

Hello Gjackson,

Could you please give the positions of the two FETS and your solution (code on schedule, FET type, etc)? I might have the same problem.