They could be badly refurbished panels with a common failure point, but I suspect they're just cheaply made and they are failing.
Can you upload a few photos of the fault, so I can confirm it's a bad panel?
tom66
Back Again?
Last Activity: Today, 08:12 PM
Joined: 04-03-2011
Location: Cambridgeshire
-
No. EDID contains only the monitor timings and manufacturer information.
You're observing the impact of a bad LCD panel, probably as a result of a design defect.Leave a comment:
-
Unfortunately not worth trying to replace the LCD glass, they don't sell it to consumers and it usually costs almost as much as a used TV. I have been where you have, cracked a 55" set once, that was really annoying. Unfortunately these large TVs are really hard to work on.Leave a comment:
-
Kevin,
You can see each of the COF chips bonded as ribbons there.
It is easy to understand the architecture if you look at the pin outs of these flexes (COF, the little brown flexes going to the panel glass).
There are two or four differential pairs entering each COF. These probably carry the high speed video data for that COF, about 1/10th of the panel going by their sizes. The job of the T-con is to decode the full video frame coming in, into individual data streams for each COF, plus gate drive signals to select the rows of the panel, whilst applying...Leave a comment:
-
No, OLED doesn't have any liquid crystal in it. But both OLED and LCD are based on TFT arrays, thin film transistors....Leave a comment:
-
Yes, OLED is based on TFT array just like LCD.
In fact, the only real difference between LCD and OLED is there is a second transistor on each cell which drives the current into the OLED pixel directly.
This cell is connected from EVDD to EVSS, the transistor is at the top of the drive stack, it is effectively a linear current regulator (common drain amplifier). The second transistor is needed because the regulation from a single transistor isn't good enough.
Typical OLED circuit:
Typical LCD circuit:
Gate...Last edited by tom66; Yesterday, 08:04 AM.Leave a comment:
-
You can test to see what ones are shorted, but I would just remove them all. Just try to touch the shell of the cable and your hand to the back of the TV before connecting it to reduce the static damage risk. Replacing them will require some really fine soldering work.Leave a comment:
-
A single pixel line is always the panel (COF chip), just because there is no other component that deals with the column signals separately....Leave a comment:
-
100% dead panel with a single pixel vertical line.Leave a comment:
-
Glad to hear you got it working.
Most likely the cause of the non functional is one or more of these ESD protection diodes being shorted.
​
​
These provide protection against static damage from handling the port yourself, or plugging in a cable that might be charged up, but will likely be damaged if a lightning surge finds its way onto them. They may then short, preventing communication with the downstream source.
You could try removing them, if you end up taking apart the TV at another time, you'll lose some immunity to static damage...Leave a comment:
-
So I suspect you have three individual strings with a common GND, current will be regulated from the high side. So I would expect if the problem was the LEDs you should either get 2/3 lit up, or the TV should flash briefly on power on as the two channels that work drive successfully and then the chip shuts down because 3rd channel hit OCV limit. Any LED tester you'd wire from LED pin to GND.
It is however possible the previous owner (you say you got the TV a few days ago?) watched the TV until all three strips died, but the picture would be pretty bad with only one dead so IDK seems...Leave a comment:
-
I would put minimal value in an AI result here, and I am not just being an AI skeptic, just that I can't imagine there is much TV repair data in its training data set and when you get to the edges of knowledge, hallucinations are common. It might be correct, it might not, but I think more testing is justified. Your choice....Leave a comment:
-
Equally though there's almost no load - perhaps only a voltage divider. So it should go up to the OCV and then shut down.
Even if you see the meter briefly show a high value and quickly fall down it's a clue the power supply is working and LEDs are open.
Some LED controllers will also drive the voltage up slowly due to soft start procedure....Leave a comment:
-
In case you haven't done this already...
Disconnect the LED connector.
Measure the voltage across the connector with power off on the DC200V range or higher.
Have a helper turn the TV on or find some way to trigger it yourself.
Do you see a voltage spike or does it stay at 0V?Leave a comment:
-
Sharp TV made in 2017 will be Sharp chassis. A good chance that any Sharp remote control will work from the same generation. You can also try a general universal remote that can be programmed, I find these to work but you sometimes have to try a few different codes.Leave a comment:
-
Thanks for the info anyway.Leave a comment:
-
Where did you put the tape?Leave a comment:
-
That's on the secondary side. You're not going to get arcing there.Leave a comment:
-
Hopefully that means the T-con board synchronises from the main board then. But unfortunately I could not say for sure.Leave a comment:
-
HDCP only impacts HDMI so if you don't need that, you should be fine....Leave a comment:
No activity results to display
Leave a comment: