Samsung UE55KS7000 and UE49KS7090 main board protection mechanism

[lotas]

They may be in this place, but I don't know for sure.

[kevinallein]

On the UE49KS7090 I am really confused. I have tried to block signals 12-22 (all CLK and CLKB) either on left or on right side with tape, but always get the same image now (see attached image).

That method seems to work for other people, what is wrong on my side ?

[kevinallein]

I took now a bunch of measurements on those test points. Looks to me as if I do not have the same problem, since those measurements at least seem to be OK.
Can the experts please look at this ? Do I have a completely different problem ?

[kevinallein]

Actually I just realized something: Since CKVx, CKVBx and STVP range from ~-10 .. 28 V, and there is a VOFFE with -9.4 V, should there not be somewhere VON / VGH with ~28 V ?

But what would be the label for this voltage ?

[William1967]

The reason that the device does not want to start up properly may be because different screens have been used.
For example:
Used in UE55KS7000
BN95-02609A CY-QK055FLLV2V/H,KS7000
BN95-02609E CY-QK055FLAV2V/H,KS7000 <-- not exchangeable and can only be used with AUO displays
BN95-02609G CY-QK055FLLV7V/H,KS7000

Used in UE49KS7000
BN95-02608A CY-QK049FLLV3V/H,KS7000

The blue PCB's are usually used in AUO panels...

[kevinallein]

On the main board there is a VON test point and I do read 0 V, so there is a problem.
However I cannot see, how VON goes to the panel. In the pinouts from the Service Manual it does not list VON.
Also the circuitry on the main board uses two ICs from Richtek RT6936A and RT6935B and I cannot find datasheets or pinouts anywhere. I would assume, that that voltage is 0 due to some protection circuit ? Since all other voltages seem to be correct and also CKVx, CKVBx and STVP have the right high voltage, I doubt that the voltage regulator actually does not work.
Does that make sense ?

[kevinallein]

Originally Posted by William1967

The blue PCB's are usually used in AUO panels...

Looking at the logo on that blue scalar board, I thought this was not AUO ? Which logo is that ? The main board has the same logo.

[lotas]

Originally Posted by kevinallein

Looking at the logo on that blue scalar board, I thought this was not AUO ? Which logo is that ? The main board has the same logo.

This emblem stands for Lead Free (LF).

[Diah]

Originally Posted by kevinallein

On the main board ....

I just saw yours photo if you did as i told you at part 2 on my post #13 swiping the mainboard..
yours problem are not Panel... its Main boards.. impossible to repair or follow chart on Sandwich boards layout

[kevinallein]

After the 55 inch worked stable with 3/4 of the panel I had it run for quite a while.
Later I worked on the 49 inch and put the 55 inch motherboard into the 49 inch TV. It seems like this did some damage to the MB, since now the 55 inch will not turn on completely again. Sometimes it starts, but than it will turn off again. When I measured this afternoon the VON voltage is also not present in the 55 inch MB now as well. Did sticking it into the 49 inch panel now damage that MB ?

[kevinallein]

The second question for me is, where is the VON voltage on those connectors ? As far as I believe to understand the functionality, VON and VOFFE must be present at the gate drivers, which are integrated into that generation of panels, but what label is used for VON ?

[Diah]

Originally Posted by kevinallein

Did sticking it into the 49 inch panel now damage that MB ?

this will not happend. even if you take hammer and smatch the panel it will not damage MB.

William1967 post#25 are the answer of why. if you put back the MB to its 55 with the U ribbon disconect as before... leav it alone it could be after 2-5 restart register the panel back as before.

you can read the panel sticker lable of the both set.

[kevinallein]

I just stuck the board into the 55 inch TV and it continously turns on and off. It shows the correct pic when it turns on, but it will not stay on continously.

[Diah]

Originally Posted by kevinallein

It shows the correct pic when it turns on, but it will not stay on continously.

so its not damaged because of the 49..
while it turn on and display the 3/4 picture plug it out direct from wall socket... leave it for about 2-3 minute then plug it again in wall... you may need to repeat this 2-3 time until the the panel registered again.

[kevinallein]

Debugging the 49 inch TV I am completely confused now. According to all I have found on the Internet the panel should receive VON / VOFF or VGH / VGL for the gate drivers (see attached block diagram).
On the main board I measured those voltages, please see the picture.
I can also measure VOFF on the panel test points and the connector to the panel. However I cannot measure the 28 V anywhere. How could that ever work ?

[kevinallein]

Originally Posted by Diah

so its not damaged because of the 49..
while it turn on and display the 3/4 picture plug it out direct from wall socket... leave it for about 2-3 minute then plug it again in wall... you may need to repeat this 2-3 time until the the panel registered again.

I did this now at least 5 times without any change in behaviour. Also I cannot turn the TV off anymore through the control button.

[Diah]

Originally Posted by kevinallein

I did this now at least 5 times without any change in behaviour. Also I cannot turn the TV off anymore through the control button.

100% there are some things wrong you did when you used the 55 MB on the 49..

the only things i can imagine.. you used ( plugged the sockets )of IR / wifi / Bluetooth boards of the 49 on the 55 MB.. any different at the sockets line pin assign will cause serious issue.

[kevinallein]

I only plugged in panel and the IR sensor, nothing else