Telefunken 55" Model TLEDD-55FHDA (bad picture)

[angelos]

Hi Guys,
Its the second time i have come across this same issue in the last month and having to give back the sets unrepaired does not pay the bills. That said i was asking for a second opinion on this fault.
The image manifests with a lot of lines horizontally at the top and bottom of the display and after a while colors spread all over the screen. A lot like a VGH, VGL, AVDD issue etc.
I am going to explain with photo's what I have seen in separate posts after this one.

[angelos]

Re: Telefunken 55" Model TLEDD-55FHDA (bad picture)

Here is a picture of the main and TCON

[angelos]

Re: Telefunken 55" Model TLEDD-55FHDA (bad picture)

I measured around the TCON and found all the voltages to be correct.
VGH = 25.8
VGL = -6.2
HAVDD = 7.8
VCC1 = 3.3V
VDD18 = 1.78

The CKV and CKL lines i am not sure of.
On the next lot of photos i will show you how the image starts off and worsens.
Photo 20231111_141917.jpg is when the set is switched on initially
and photo 20231111_140411.jpg is after one minute of running

[angelos]

Re: Telefunken 55" Model TLEDD-55FHDA (bad picture)

On the TCON connecting to the panel there are two ribbons if i disconnect the right side ribbon i get.... check photos

[angelos]

Re: Telefunken 55" Model TLEDD-55FHDA (bad picture)

If I reconnect the ribbon and change to the other side the results are the same as in the photo's except in it's the other side now. Taping off the CKV and CLK lines makes no difference.
My question is, TCON or Panel???????????????????
I have a oscilloscope and can take waveform measurements to diagnose if someone on the forum has experience on this kind of issue.
I wish i knew how to force the TCON into aging mode to exclude main board issues but i dont know how to. It;s a chinese secret.

[EazyBone]

Re: Telefunken 55" Model TLEDD-55FHDA (bad picture)

With some tvs, you can disconnect the main board and tcon and put 12v on the fuse jumpered from a 12v line. On some tvs this will cycle picture as a full solid color. Research before you do this but works on some sony and Hisense you then would see if those lines still exist and would know tcon or panel.

[angelos]

Re: Telefunken 55" Model TLEDD-55FHDA (bad picture)

With some tvs, you can disconnect the main board and tcon and put 12v on the fuse jumpered from a 12v line. On some tvs this will cycle picture as a full solid color. Research before you do this but works on some sony and Hisense you then would see if those lines still exist and would know tcon or panel.

I did unplug the LVDS cable entering the TCON and used a external 12V PSU to power the panel. It came up blank. I tried doing research on the TCON on how to force the burn-in or aging mode but found squat.

[arizanotlari]

Re: Telefunken 55" Model TLEDD-55FHDA (bad picture)

For Fhd : Apply 3.3V to pin-44.

51 50 49 48 is panel vcc

7. Specific pin No. #44 is used for “No signal detection” of system signal interface.
It should be GND for NSB(No Signal Black) during the system interface signal is not.
If this pin is “H”, LCD Module displays AGP(Auto Generation Pattern).

[angelos]

Re: Telefunken 55" Model TLEDD-55FHDA (bad picture)

For Fhd : Apply 3.3V to pin-44.

51 50 49 48 is panel vcc

7. Specific pin No. #44 is used for “No signal detection” of system signal interface.
It should be GND for NSB(No Signal Black) during the system interface signal is not.
If this pin is “H”, LCD Module displays AGP(Auto Generation Pattern).

Thank you for your response Arizontlari.
I need to fully understand what you are explaining to me.
1. When applying 3 3V to pin 44, are you talking of pin 44 of the big square IC in the middle of the tcon?
I only have one power supply which can feed the panel voltage (12V) to the tcon. Should I look on the tcon for a derived voltage? A 3.3V rail?

2. You said pin 51 50 49 48 is panel vcc. Which pins are we talking of? The LVDS feed cable or the big square ic in the middle of the tcon?

3. Do you have literature or a datasheet on the chip that I can study?

Thanking you in advance
Angelos

[angelos]

Re: Telefunken 55" Model TLEDD-55FHDA (bad picture)

After meditating on what you said I drew on the picture a white line representing what I understand from what you said. Have a look at the picture.
On the right of the tcon next to the lvds connector is a plug cut out on the pcb. The pin on the far right seems to be labeled 3.3V. I must just check what grounds pin 44. Pin 44 is also connected to pins 46 45 and 39.

[lotas]

Re: Telefunken 55" Model TLEDD-55FHDA (bad picture)

39, 44, 45, 46 - gnd

[angelos]

Re: Telefunken 55" Model TLEDD-55FHDA (bad picture)

Please help me understand. Have a look at the photo I have attached and check the comments. I don't understand where to apply the 3.3V to force chip into test mode.

[angelos]

Re: Telefunken 55" Model TLEDD-55FHDA (bad picture)

I checked further and found a group of resistors. Please check the photo.
If I study that circuit then currently pins 3 and 4 of the KIWIMAGE (KV7626) chip are at a zero potential because R28 (4K7) pull down resistor and R26 (4K7) pull down resistor force these pins to a logic zero. Those other spots where no resistors are installed namely (R23 and R21) are where i bridge it out to add the 3.3V supply to the chip

I have done it logically,

Pin 3 Pin 4 Result
Logic state 0 0 Blank image
0 1 Blank image
1 0 Blank image
1 1 Blank image

So, no luck. Any comments?

[arizanotlari]

Re: Telefunken 55" Model TLEDD-55FHDA (bad picture)

39, 44, 45, 46 - gnd

Please help me understand. Have a look at the photo I have attached and check the comments. I don't understand where to apply the 3.3V to force chip into test mode.

According to LG standards, the 44th leg is used for AGP, but in some TCONs this leg is used, while in others it is used as gnd.

Unfortunately, AGP cannot be activated because this leg is grounded in the tcon in question.

[angelos]

Re: Telefunken 55" Model TLEDD-55FHDA (bad picture)

All right, so you are saying it cannot be tested on my TCON design.

Just to clarify things, when you are talking of LG standards are you referring to the TCON. Is this an LG design TCON? So the LVDS plug follows a certain standard pin layout on some TCONS?

[arizanotlari]

Re: Telefunken 55" Model TLEDD-55FHDA (bad picture)

Didn't you know this? Some of the 51-pin lvds have 3, some 4, and some 5 supply pins. These (in my opinion) set the standard of LVDS. If you examine the schematics of TVs of different brands (Samsung, LG, etc.), you can see the differences.

[angelos]

Re: Telefunken 55" Model TLEDD-55FHDA (bad picture)

I have never seen a single tcon schematic. It seems it's a bloody chinese
secret