UN55D6000SFXZC no video issue

[basha318i]

Hello,

I know this has been discussed several times in this forum; but usually people tend to replace the whole board; while I'm trying to figure out what's wrong with it & replace it as a last resort. As I'm trying to learn while fixing this TV.
Here's what I have so far; please feel free to correct me if I'm wrong:

My issue is not in the power board. Simply because when I disconnect the main board the LED’s come on; which I believe means that there’s a short somewhere in the main board.

So here’s what I’ve found so far:

1. LED’s come on when I disconnect the MB.

2. tested the voltages out of the PS board & they all check.

3. F11 (fuse) in T-con board is good (continuity) but it has zero voltage.

4. PANEL_VCC is dead in the MB; it should read 13v (not sure)

5. PANEL_VCC is the output of protection IC IC210.

6. IC210 has good input to it coming from the PS board via the 20 pin connector.

7. IC210 EN (Enable) pin is dead; as if whatever (I think should be the MCU) turning it on so it can supply voltage to the panel is not.

8. IC210 is good; I applied 5v to the EN pin & it turned on; which delivered the 13v to the T-con board.

9. The TV is responsive to remote; I mean when you press buttons in the remote the stand by LED blinks; not sure if this acknowledgement is coming from the MCU or a simple IR circuitry in the IR transponder board.

I cannot find schematics for the main board so I can troubleshoot it further; any help would be appreciated.

[neilc6]

Re: UN55D6000SFXZC no video issue

12V to the tcon is typically switched through a FET with an on signal from the processor. Hard to find schematics for main boards. Things you can check are on board regulators. The D model year main boards do have a lot of flash memory failures. You can spray with upside down can of duster to freeze it before plugging in.

[budm]

Re: UN55D6000SFXZC no video issue

Try as neilc6 suggest, right now more likely that the main is not sending PS-ON, BL-ON, DIM, and on command for the switched 12V for running the T-CON.

[basha318i]

Re: UN55D6000SFXZC no video issue

12V to the tcon is typically switched through a FET with an on signal from the processor. Hard to find schematics for main boards. Things you can check are on board regulators. The D model year main boards do have a lot of flash memory failures. You can spray with upside down can of duster to freeze it before plugging in.

Thanks for your reply & recommendation; I've tested every transistor according to the poor service manual & all voltages are present & correct.

I'm not sure I do understand spraying a duster with upside down; do you mean to cool down the main board might get it to work? Sorry I'm trying to learn here.

[basha318i]

Re: UN55D6000SFXZC no video issue

Try as neilc6 suggest, right now more likely that the main is not sending PS-ON, BL-ON, DIM, and on command for the switched 12V for running the T-CON.

Thank you for noting that; I have tested these signals in the 20-pin connector & they seem to be fine, or maybe I'm just missing something?

[budwich]

Re: UN55D6000SFXZC no video issue

list the pins (labels) and readings that you get on each so the forum can see what you are saying is "fine".... "fine" some times is in the eyes of the beholder, learning or not.

[neilc6]

Re: UN55D6000SFXZC no video issue

I"m not sure I do understand spraying a duster with upside down; do you mean to cool down the main board might get it to work? Sorry I'm trying to learn here.

An inverted duster will spray out the propellant only acting like freeze spray. You want to freeze the flash module.

Here is a video of a D series flash replacement.

https://youtu.be/812DCrpZufk

[budm]

Re: UN55D6000SFXZC no video issue

Thank you for noting that; I have tested these signals in the 20-pin connector & they seem to be fine, or maybe I'm just missing something?

Are you sure they are fine? So what are the readings for the control signals that goes to the power supply board?
It cannot be fine if you turn on the TV but the backlights do not come on when you have every things all connected back up.
You should read Basic LCD TV troubleshooting to know what the TV needs to function.

[diif]

Re: UN55D6000SFXZC no video issue

An inverted duster will spray out the propellant only acting like freeze spray. You want to freeze the flash module.

Here is a video of a D series flash replacement.

https://youtu.be/812DCrpZufk

The UN55D6000SFXZC uses OneNAND, not the TSOP48 NAND in this video, that's on boards up to 46". It would have been obvious had the OP posted photos.