Philips 55PUS6704 no picture, backlight ok

[Patrick501]

Hello,
I'd like to repair a Philips 55PUS6704.
It turns on and you can see the backlight, hear the sound but no picture.

When I disconnect one of the T-con cables, half of the screen turns white.
right cable disconnected= right side white
left cable disconnected= left side white

When I tape like 6 or 7 pins of one cable it looks like the picture attached. I already tried another T-con board without success.
There are no shorts on the the mainbaord and the two lcd panel boards...at leat I couldn't find any.
Also you can notice one single blue line in the right half if you take a closer look. It also stays no matter whoch side is connected or disconnected. Maybe it's a LCD failure and not fixable...

I hope anyone can help?

[lotas]

Are there TVS diode assemblies (usually two of them) along the edges of the panel buffer strips?

[Patrick501]

Are there TVS diode assemblies (usually two of them) along the edges of the panel buffer strips?

only resistors and caps, no tvs

[Diah]

When I disconnect one of the T-con cables, half of the screen turns white.
right cable disconnected= right side white
left cable disconnected= left side white

this mean yours T-COn and Panel are fine, so the issue with MB signal... start with Firmware
download and unzip, put upgrade_loader on USB Stick formatted FAT32 MBR mode... ( Must MBR Mode ) if you saw upgrade in progress good,,, if not leave it do wjat it should untill the Tv reboot

[lotas]

Where is the panel in order, did you even look at the first photo?

[Diah]

Where is the panel in order, did you even look at the first photo?

read his first post again... with disconnect one side he got solid white at other half,,, i quated at my post, the photo you mentioned he did Tape masking

[Patrick501]

this mean yours T-COn and Panel are fine, so the issue with MB signal... start with Firmware
download and unzip, put upgrade_loader on USB Stick formatted FAT32 MBR mode... ( Must MBR Mode ) if you saw upgrade in progress good,,, if not leave it do wjat it should untill the Tv reboot

I downloaded the file, unzipped, put the file on a USB Stick (FAT32, MBR) and plugged it into the TV.
After abot 3mins the TV rebooted. Nothing changed. Do I have to wait any longer?

[Diah]

I downloaded the file, unzipped, put the file on a USB Stick (FAT32, MBR) and plugged it into the TV.
After abot 3mins the TV rebooted. Nothing changed. Do I have to wait any longer?

if it reboot then it write the firmware... show here yours MB & T-CON clear focused photo

[Patrick501]

if it reboot then it write the firmware... show here yours MB & T-CON clear focused photo

there you go

[Diah]

yours SoC Mediatek MT5806, from my experiences it lags with his poor GPU Mali G51
disconnect the LVDS between MB and T-CON, turn on see if the LED BL come on,, if yes,, you need to take from PSI or MB rail 12V DC , and feed it direct on T-CON Fuse... turn on see if the screen start displaying color

[Patrick501]

yours SoC Mediatek MT5806, from my experiences it lags with his poor GPU Mali G51
disconnect the LVDS between MB and T-CON, turn on see if the LED BL come on,, if yes,, you need to take from PSI or MB rail 12V DC , and feed it direct on T-CON Fuse... turn on see if the screen start displaying color

I disconnected the lvds cable between MB and T-Con. Backlight comes on, connected 12V to fuse but the screen stays dark. I soldered a cable on the fuse. So the connection is 100% and it definitely has 12V.

[Diah]

I disconnected the lvds cable between MB and T-Con. Backlight comes on, connected 12V to fuse but the screen stays dark. I soldered a cable on the fuse. So the connection is 100% and it definitely has 12V.

okay... good done.. now remove yours jumpers , put back the LVDS in it place... be sure the Fuse on T-CON are fine first... then you have on each side at the Panel buffer boards at the middle under the speaker area one U shaped Ribbon cable... disconnect from each side once a time.. and check when you turn on the set what will the screen display at each time

[Patrick501]

then you have on each side at the Panel buffer boards at the middle under the speaker area one U shaped Ribbon cable... disconnect from each side once a time.. and check when you turn on the set what will the screen display at each time

Can you tell me where this u shaped ribbon cable is supposed to be? I can't see anything like that.

[Diah]

take out the metal holder at the middle of each side and look under it

[Patrick501]

take out the metal holder at the middle of each side and look under it

I removed the metal holders (if you mean them) but there's nothing under it

[Diah]

I removed the metal holders (if you mean them) but there's nothing under it

this is COF to glass panel ... you don't have them... its cheaper One SoC TV like mobile... the things you can do to be sure the Panel VCC didn't broken , take out the Bezel and inspect carefully all round the panel if there any broken at glass , if you don't find then replace MB or reflow the one SoC MT

[Patrick501]

would it even be possible according to my tests of my first post that a broken panel cause this kind of error?
I'm thinking about giving the SOC a reball. I hope I have the right stencil here...

[Diah]

would it even be possible according to my tests of my first post that a broken panel cause this kind of error?
I'm thinking about giving the SOC a reball. I hope I have the right stencil here...

panel vcc at this kind of Panel ruining around the panel are thin film folio under the glass, we need to be sure there are no broken first, then you go to re ball

[lotas]

Why reball and ruin the motherboard if the panel doesn't pass the 12V test?

[Patrick501]

Why reball and ruin the motherboard if the panel doesn't pass the 12V test?

so you think, when I inject the 12V into the disconnected T-con (screen connected of course) there has to be a visible difference on the lcd? If not, it not a SOC issue?
Is that correct?