Possible TCON board failure: Phillips 46PFL9706K

[spartantravis]

Hello Ladies and Gentlemen

I am trying to repair a Phillips 46PFL9706K LED TV with an intermittent display issue. I have posted a video describing the issue below

https://youtu.be/pyVy-E3AczM

Things about the TV screen
The previous owner was about to throw it out due to the problem. The TV has not had any other maintenance nor has any other defects. There is no physical damage to the TV. The Backlight and audio function perfectly which has lead to think that the mainboard and power supply are in working condition. I already have my own TV so I would like to use this to improve my repair skills.

What have I done in terms of repair attempts?
I have opened up the back to ensure that there were no loose cables. I have attempted to reproduce the problem on demand by wiggling the LVDS cables to and from the TCON board (CPWBX 4920TP). The problem cannot be triggered by this method which I think rules out a loose cable/defective cable (feel free to contradict me on this).
I have not removed the front bezel to check the TCON to LED ribbons as the problem occurs over the entire screen and does not produce the coloured lines consistent with a loose ribbon. I have disconnected each of output ribbons from the TCON board (index.jpg) individually. The screen appears white on the left or right side (depending on which cable is disconnected) but no image appears and only the subtle differences in backlight variation appear.
An Physical inspection of all the board has not revealed a bloated /bulging capacitors but I have not rigorously checked these with a multi-meter yet.

The black chip in the centre of the TCON board (index.jpg) can become hot to touch (not sure if that is because I have unscrewed the shield.

Frequency of the problem
The issue began over the space of a few months. The problem may occur within a few minutes after switching on the TV or may occur after a few hours of use. It has become more frequent lately

Questions
I am unsure how to loosen the LVDS cables. I have not seen a cable/ribbon fastened like the ones in the picture. Is there a trick to it or is it bonded to the boards?

Is this Problem symptomatic of a failing TCON board?

Has anyone else ever seen this type of a intermittent screen distortion?

Any help or further questions would be much appreciated

[CapLeaker]

Re: Possible TCON board failure: Phillips 46PFL9706K

Hmmm... that's a nice bonus feature! When this fault state happens, does the sound keep on working fine? Sine it happens after the TV runs for a while, just take the back off the TV and use wifey's hair dryer. Blast the Tcon and the main board. Also clean these flat ribbon cables between main board and Tcon (both ends) and the Tcon to the panel. Use a white eraser or 99% pure rubbing alcohol. Also once it acts up, freeze parts of interest on the Tcon and or Main Board with a can of air upside down. Post the results!

[William1967]

Re: Possible TCON board failure: Phillips 46PFL9706K

The solution is know, a resonator is not good anymore. See attached picture.
The resonator is 25Mhz, replace it and it will work again.

[Maalobs]

Re: Possible TCON board failure: Phillips 46PFL9706K

Here is a link to the service manual that covers your model:
https://www.electronica-pt.com/esque...ileinfo/33769/

It has detailed instructions for disassembly and fault finding, and is complete with circuit diagrams and PCB layouts.

This manual covers a chassis that is used in several TV-models.
Look up your model name in Table 2-1 to see which sections in the manual are relevant to your particular model.

Say what you want about Philips, but they have excellent service manuals.

[spartantravis]

Re: Possible TCON board failure: Phillips 46PFL9706K

Much appreciated everyone. I FInally found time to use your advice to see if I could get it working again @william1967: I was unable to remove the resonator from the board. I applied some flux and tweezers to the part you highlighted in red. It was not possible to remove it. I did put the tcon board back to the tv and the problem has not appeared yet (+1 hour) The problem was continuous from the moment I powered on right before I attempted this. Can this be a fluke? Is overheating the resonator with a soldering iron risky or is it analogous to hitting an engine with a hammer to fix a problem?

Thanks for the manuel link Maalobs

@capleaker : I did remove the LVDS cables in the process of trying to remove the tcon board to remove the resonator. I did not try the compressed air trick, nor did I clean the tips. I will attempted that next

[nomoresonys]

Re: Possible TCON board failure: Phillips 46PFL9706K

Sometimes it can just be a bad/dirty connection, will know after it runs a few hours.

[spartantravis]

Re: Possible TCON board failure: Phillips 46PFL9706K

Well it has been a few weeks now and there is no interference pattern. I am not sure if it was the reseating of the LVDS cables or touching the resonator with the soldering iron. Anyone care to speculate?