Has anyone ever repaired a bad panel driver?

[johniwad]

Just curious to know if anyone has ever repaired an LCD panel driver board. I believe I have a bad panel as I've replace everything else in the TV. TV has sound and back light but screen stays black. Tabbing on panel looks good too. I'm thinking possibly bad components on LCD panel driver board. Can't find schematics or even a general breakdown of how the driver board works. Does anyone know what usually goes bad on the panel driver board?

[freakaftr8]

Re: Has anyone ever repaired a bad panel driver?

Have you tried only one ribbon connection at a time between the tcon and LCD panel? This would mean pulling the ribbon from the right side only allowing the panel to be driven from the left side of the tcon.

Then reverse the process with the opposite side.

Also can you provide model number of tv?

[freakaftr8]

Re: Has anyone ever repaired a bad panel driver?

I successfully repaired a Sony XBR55X850B the other day that had a shorted MLCC capacitor on the panel driver board. It had no picture on the shorted side, white screen with faint vertical lines on the other side.

[budwich]

Re: Has anyone ever repaired a bad panel driver?

depending on the panel (which you have provided no info), lots of things can be done.... from removing the side tabs (one side), to testing / replacing capacitors on edge boards, to "pressure pads" to help with connectivity. So "fix" might be "workaround".

[johniwad]

Re: Has anyone ever repaired a bad panel driver?

Have you tried only one ribbon connection at a time between the tcon and LCD panel? This would mean pulling the ribbon from the right side only allowing the panel to be driven from the left side of the tcon.

Then reverse the process with the opposite side.

Also can you provide model number of tv?

Yes I tried that no difference, screen stays black. Model is a Samsung
UN40J6300AFXZA

[johniwad]

Re: Has anyone ever repaired a bad panel driver?

depending on the panel (which you have provided no info), lots of things can be done.... from removing the side tabs (one side), to testing / replacing capacitors on edge boards, to "pressure pads" to help with connectivity. So "fix" might be "workaround".

TV is a Samsung UN40J6300AFXZA only seen tabs at the bottom of panel. All the tabbing looks good pressing on them makes no difference.

[budwich]

Re: Has anyone ever repaired a bad panel driver?

well then your first / next step would be to provide good information about the various voltages that are present as per the circuit board "printing" in and around any connectors / interconnection especially with respect to the power and main board and maybe tcon if it is different from the main boards.

[nomoresonys]

Re: Has anyone ever repaired a bad panel driver?

https://www.youtube.com/watch?v=4v8DcqCNG4A
Powersupply testing, Heed the HIGH VOLTAGE WARNING CAN BE DEADLY, inverter boards can have 1000 volts and more, be careful with those too, if you work on any.

[budm]

Re: Has anyone ever repaired a bad panel driver?

http://www.shopjimmy.com/samsung-bn9...-con-board.htm
Is that your T-CON board?
Did you verify that you have 12VDC at both ends of the SMD fues with ref to the chassis GND?

[lookimback]

Re: Has anyone ever repaired a bad panel driver?

Yes, a few. Most recent one was an LG 55LE5400. Had a single shorted MLCC on left driver. Had something with a bad LM1117 on the driver once too. Disconnect one ribbon cable at a time and power on(never hot swap), you should be able to get a half picture. If you've already tried that and got nothing, then it is probably before the drivers.

[freakaftr8]

Re: Has anyone ever repaired a bad panel driver?

The Sony I worked on did not have a picture on either side but one side did represent a white screen with faint vertical lines. That side did not have the shorted capacitor. The side that did have the short capacitor would not show a picture at all. I guess or is always a slight possibility that both sides have a shorted capacitor Or there some interlinking between the 2 sides

[lookimback]

Re: Has anyone ever repaired a bad panel driver?

Must have been some interlinking between the sides.

[johniwad]

Re: Has anyone ever repaired a bad panel driver?

Yes, a few. Most recent one was an LG 55LE5400. Had a single shorted MLCC on left driver. Had something with a bad LM1117 on the driver once too. Disconnect one ribbon cable at a time and power on(never hot swap), you should be able to get a half picture. If you've already tried that and got nothing, then it is probably before the drivers.

I did order T-Con board from ebay. It could have been bad. So to be sure I ordered another one. I should get it soon.

[freakaftr8]

Re: Has anyone ever repaired a bad panel driver?

I should note that this model has exceptionally bad issued with BGA soldering under the main processor. Could be something to look at. Apply some heat around the board and see if situation changes.

[johniwad]

Re: Has anyone ever repaired a bad panel driver?

I should note that this model has exceptionally bad issued with BGA soldering under the main processor. Could be something to look at. Apply some heat around the board and see if situation changes.

Notice that big heat sink and thought about that too. I may reflow or try a reball if I have the stencil. Funny thing is I bought a mainboard off ebay and had the same issue. I know the board I bought could be bad though.

[freakaftr8]

Re: Has anyone ever repaired a bad panel driver?

Just try take a hair dryer and heat it up and see if the picture comes back

[maxvalutech]

Re: Has anyone ever repaired a bad panel driver?

Very rarely do I pay for any TV. I advertise to take away non workers. Generally I avoid broken screens as just too many different models of tv . This week I have a friend bringing me 5 TVs for nought and asking if I have anything over 45" to sell as he has a buyer for me. In another two months a council cleanup occurs - last year I advertised just before that to "keep them out of the compactor" and finished up with 20.

[johniwad]

Re: Has anyone ever repaired a bad panel driver?

Just try take a hair dryer and heat it up and see if the picture comes back

Heat up the main board?

[johniwad]

Re: Has anyone ever repaired a bad panel driver?

I'm really leaning toward a bad panel. I have tested with two different main boards and two different t-con boards and have the same results. I will upload pics of the panel driver boards if anyone want chime in on where possible problems could be.

[budwich]

Re: Has anyone ever repaired a bad panel driver?

as suggested earlier, list and check the voltages of the various pins / connectors that are listed / printed on the boards (either main and power and tcon). This will provide the forum with some understanding of what's happening with the set electronically.