Author Topic: EEVblog #794 - Samsung Dumpster LCD Repair Connector Followup  (Read 12135 times)

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Offline bktemp

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Re: EEVblog #794 - Samsung Dumpster LCD Repair Connector Followup
« Reply #25 on: September 18, 2015, 01:08:08 pm »
My recollection of the previous videos in this series are that Dave focused on the column drivers. Could vertical stripes like this be caused by leaking row drivers?
It looks so. Since the whole panel is affected all row driver ics beeing bad is unlikely. So I don't think the actual panel or the row or column drivers are the problem.
It could be a bad connection somewhere between the TCON and the panel or a failed voltage on the TCON board.

@ Dave
Look for a negative voltage on the TCON board or on the LCD panel. Maybe it is labeled VGL or GOFF.
It is usually generated using a charge pump near the main boost converter on the TCON board, because they tap of the signal from the switching node.
« Last Edit: September 18, 2015, 01:11:14 pm by bktemp »
 

Offline repairfanatic

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Re: EEVblog #794 - Samsung Dumpster LCD Repair Connector Followup
« Reply #26 on: September 21, 2015, 11:21:51 am »
Hi mr. dave jones.i saw your video about the samsung with  vertical lines and bars showing up after turning the tv on. the problem is the lcd screen itself. but the tv can still be fixed without replacing the panel or the lcd screen.we had similar walk in units with the same problem and managed to fix them. what we do is we increase the Voff voltage to -16 volts. with some bigger sized TVs we increase it to -18 volts. that negative voltage is responsible for the TURN OFF STATE of the TFTs. there is a feedback resistor for the Voff regulation mr jones. lessen its value and you will notice the Voff voltage will go up.
 


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