Philips 42PFL3609S/98 Shuts down after sometime

[vernond]

Hi.

I have a Philips 42PFL3609S/98 TV that shuts down after some time. If the TV is not power overnight and is powered on in the morning then it will last longer sometimes up to 2 hours. After the first shutdown, it will be more difficult to switch it on again. It would be easier to restore power if I remove the AC cord and plug it back again.

Replacing capacitors C805 and C804 didn't solve the problem but made the running time last slightly longer. The old capacitors were giving me a reading of 920 uf. C840 and C840A are giving out a reading of 72uf and were not replaced. The rest of the capacitors and diodes were checked and found to be within tolerance.

Could the problem be with a faulty CCFL? I have no idea how to get to them? There is a barely visible dark horizontal line across the screen. Any help would be highly appreciated.

[tiki66]

Re: Philips 42PFL3609S/98 Shuts down after sometime

Does it switch off just the LCD, the backlight or the whole tv shuts off?

[vernond]

Re: Philips 42PFL3609S/98 Shuts down after sometime

The whole TV shutsdown with the relay K801 de-energizing can be heard. Does anyone know the function of this relay?

[Davi.p]

Re: Philips 42PFL3609S/98 Shuts down after sometime

try disconnect the tcon and let the tv stay on longer than usual possibly, if it happens probably a bad semi shorted mosfet on the tcon.. if it doesn't happen try the psu alone with dummy loads and main stage on by proper ps-on like command.. watch if it stays fully on, if it stays then to be seen are dc dc regulators on main board, if none of them then CPU soldering problem...
Further, tell me if it is present FRC board, between mainb. and tcon..

[R_J]

Re: Philips 42PFL3609S/98 Shuts down after sometime

I would suspect the small caps like C803 in the standby circuit, or C802 for the main power supply

[vernond]

Re: Philips 42PFL3609S/98 Shuts down after sometime

I would suspect the small caps like C803 in the standby circuit, or C802 for the main power supply

All these caps were check and found to be ok.

However, I noticed a bulging cap on the mainboard. Bad eyesight made me miss this cap the first time around. Removed it from the board and found the 470uf / 10V cap is giving me only 100uf. Replaced this cap now waiting to test it tomorrow.

[Davi.p]

Re: Philips 42PFL3609S/98 Shuts down after sometime

Expect no success...

[dick_barton]

Re: Philips 42PFL3609S/98 Shuts down after sometime

The service manual refers to DV10 on page 16 and it looks like the capacitor C124 is one of the filter capacitors on that line. DV10 feeds the supply to quite a few IC's so could well be the issue.

[Davi.p]

Re: Philips 42PFL3609S/98 Shuts down after sometime

Today is an old lesson to understand, when caps fails them shows defect at cold... never seen one that does different... please update...

[vernond]

Re: Philips 42PFL3609S/98 Shuts down after sometime

After replacing the 470uf/10v cap on the mainboard the tv is even more difficult to turn on. This is the symptom of failure, sorry for the background noise, getting the little one to reduce the volume is not easy. https://youtu.be/gRlltDRHOVQ

Disconnected the TCON connector from the mainboard and tried to switch on the TV, still unable to on. The symptom is the same as the youtube video.
Disconnected the power to the CCFL tubes, The symptom remains the same as the youtube video.

After knocking the power board, the tv came to life but didn't even last for 1 minute and the power begin to cycle as per the youtube video. All the time when the power cycles on and off the relay can be heard energizing and de-energizing.

[Davi.p]

Re: Philips 42PFL3609S/98 Shuts down after sometime

You don't have followed all my suggestions, if you are not able please bring it to a repair center, in your country repair is still a convenient job..

PS: i'm suspecting something wrong in the AC det circuitry wherever it is present, so search for the schematics, of the psu, i'm sure i'll find them, then test every part of that simple circuit, again , if you are able...
Get the service manual and check your led blinks error code, if it says i'm right, before test it...

[vernond]

Re: Philips 42PFL3609S/98 Shuts down after sometime

Davi, I've tried to do what you have suggested like disconnecting the TCON board, the rest of your suggestion is beyond my capability.

[vernond]

Re: Philips 42PFL3609S/98 Shuts down after sometime

You don't have followed all my suggestions, if you are not able please bring it to a repair center, in your country repair is still a convenient job..

PS: i'm suspecting something wrong in the AC det circuitry wherever it is present, so search for the schematics, of the psu, i'm sure i'll find them, then test every part of that simple circuit, again , if you are able...
Get the service manual and check your led blinks error code, if it says i'm right, before test it...

Thank you for your valuable advice. The schematics of the power supply is attached to my first post. Will check the blink error code in the service manual.

Found the service manual and attached to this post

[Davi.p]

Re: Philips 42PFL3609S/98 Shuts down after sometime

There is no AC det, you must follow the manual on how to enter SDM mode and see level 2 error blinks in the first part of manual....

[vernond]

Re: Philips 42PFL3609S/98 Shuts down after sometime

There is no AC det, you must follow the manual on how to enter SDM mode and see level 2 error blinks in the first part of manual....

Ok thank you. Will try to do that now.