TCL 55S451 Blank screen

[x_orange90_x]

Any pictures available of the working fix? I have the same TV in the same situation, but am unclear on what part of the ribbon cable for the right side I need to tape to attempt a fix.

I don't have a picture of what I did. What I suggest is you find the clock signals yourself and then block them with tape. The way I found them was by looking at the main board and finding the labels near the ribbons. When I found CLK1 thru CLK8 (I believe it was) I followed the trace to the ribbon connector. Using a multimeter in continuity, place one probe on the the pin of the connector and run the other probe along the pins of the opposite side of the ribbon (the end that plugs into the strips on the panel) until you hear a beep. When it beeps you've found where that signal comes out on the other end. All you need to find is 1 and 8 then everything in between those are the remaining signals. Start by putting tape over all 8 and see what happens.

This is assuming your multimeter BEEPS when continuity is found.

[amxlink]

Update:

I revisited the tape method and successfully found the clock signals, blocked them, and the end result looks great! I can't see any anything wrong with the picture!

Any pictures available of the working fix? I have the same TV in the same situation, but am unclear on what part of the ribbon cable for the right side I need to tape to attempt a fix.

[x_orange90_x]

You gonna sell a tape TV?

This one was more or less a proof of concept and personal achievement 😄

The ones I DO sell I've either replaced power supply components, boards, or most commonly, backlights. On rare occasion I get one that has nothing wrong with it at all.. And those are the ones I can't guarantee anything AT ALL.

But as far as used TVs go, they're just the same as used cars. You can put a new transmission in a car and sell it but 6 months later a head gasket goes. I may put a new power supply in a TV but I can't guarantee that the backlights won't fail next week. That's why I will honor my work and my customers for a respectable length of time.. but obviously not forever.

[EazyBone]

You gonna sell a tape TV?

[x_orange90_x]

Well at least you got a 4th garage TV 😂 😂

😆 I have way more than 4 in there! I fix and resell most of them. Just picked up another 55" Samsung 4k last night.. Added to the "needs backlights" pile along with a 55" Element, 50" Toshiba, and 75" Vizio. Funny thing is, I don't even USE a 4k in the house, only 1080p lol can't really tell the difference

It was just nice to save this one finally because I was probably one more garbage day away from evicting it.

[EazyBone]

Well at least you got a 4th garage TV 😂 😂

[x_orange90_x]

Update:

I revisited the tape method and successfully found the clock signals, blocked them, and the end result looks great! I can't see any anything wrong with the picture!

[x_orange90_x]

Throw it in the trash

After watching the following video I think I might dust this TCL off and give this a try!

https://youtu.be/bdw8Mub9ReU?si=a2J11CRKriWQSTZP

If I do this, would I apply 12v to the VCC leg of that IC in order to get a "smoking gun"? About how many amps would be appropriate?

Lastly, do you think this may work on my case? 😁

[EazyBone]

Throw it in the trash

[x_orange90_x]

Did I lose you guys?

[x_orange90_x]

maybe check all the resistors on the right side.

I previously did a resistance check on all of them and they read correctly. Should I check them another way? I don't understand how blocking the clock signals gives me grey on the right and image on the left, but uncovering just one makes the whole screen black again.

[nomoresonys]

maybe check all the resistors on the right side.

[x_orange90_x]

I checked the left side voltages with the right side ribbon disconnected and get the following:

DVDD1 = 1.83V HVAA= 6.73V
VAA= 15.32V
VCM1= 4.19V
VSS1= -5.03V
VSS2= -8.91V
AVCM= 4.19V


Notice the left has VSS instead of VGL. So clearly I'm missing voltages on the right. If I check the left side with the right ribbon connected I get almost the exact same readings as the right side, so the right side brings down the left when it's connected.

[x_orange90_x]

Yes, check it out.

I noticed my labels are quite different from what would be expected. The only one that sticks out to me is DVDDI. Should be 3.5V and I'm under 2V. What do you think?

[x_orange90_x]

Yes, check it out.

All ribbons attached, no tape, and power on:


DVDDI = 1.83V
HVAA = -3.8mV
VAA = -0.376V
VCM1 = -0.363V
SPI_DI = 120.6mV
SCK = 120.3mV
SPI_CS = 3.25V
SPI_DO = 3.27V
VGL1 = -3.0V and increases toward 0
VGL2 = -8.93V
AVCM = -.362V

[lotas]

Yes, check it out.

[x_orange90_x]

Check also VGH, VGL, 3.3v..., there are many more control points there

Ok. Do I just check voltage between the test point and ground with it plugged in and turned on?

[lotas]

Check also VGH, VGL, 3.3v..., there are many more control points there

[x_orange90_x]

If none of the capacitors have low resistance (in Om), then they are fine, show where you masked the contacts.

Attached is a photo of the lines I blocked off. The 4th line is STV, then CKV 8, 7, 6, 5, 4, 3, 2, 1 in that order from left to right. I checked continuity on them to find that's what they are via the test points over each of their resistors. With the tape in place I rechecked and the first untaped one (STV) still has continuity, so I know I blocked off ONLY the clock lines.

I also checked all of the caps for short to ground and all are ok.

[x_orange90_x]

lotas

I'm going to reattempt the tape trick tonight and I'll take a photo of it for you. I'm hoping I can find a bad component on the scaler to fix the issue rather than the tape. If I can FIX it the image will be perfect, but the tape trick will likely cause some lines or something.