LCD TV and Monitor basic troubleshooting guides

[khamis54]

Thank you very much .Hello, i'am new

[dph1134]

Originally Posted by budm

I cannot find the original post so this is the new post that I will have it liked to my signature file. It will be good if it can be on the sticky.

Notes: When make voltage measurement in the DEADLY Primary (HOT) side, the negative leg of the LARGE filter cap will be the ground ref.
The chassis will be the ground ref for the Secondary (COLD) side.
You should at least plug the unit you are working on into the GFCI outlet for safety.

Mr. Bud Martin: Would you by chance have ever serviced an Acer power board, part # 55.L3403.001. If you have can you tell me which model numbers of Acer monitors use this part number? I'm trying to fix a NEC LCD1700M+ monitor. The service manual for this model does not show me a schematic for the power board, which is the Acer 55.L3403.001. Please reply, your help wis appreciated. Thank you.

[sbstroeing]

Thanks, Bud M! this is great!

[padulenko]

Hi guys, I have a problem.I have a Sony kdl40ex720 lcd tv.The problem is that I have a sound and a picture but it is all green.When I get into the menu its also green.And I dont know what can be a problem.The tv was brought 3 years ago. Please help.

[budm]

Another successful troubleshooting to locate bad inverter transformer.
http://www.badcaps.net/forum/showthr...957#post472957

[shoneyman2001]

great post

[budm]

Led string indicator to find out which string is dead.

[Zook]

Bookmarked.

[budm]

EEFL info

[budm]

Sony KDL-40EX400 shutdown problem with firmware fix:
http://www.badcaps.net/forum/showthr...842#post480842

[budm]

JVC power supply training.

[budm]

GFCI outlets and lamp in series with UUT (Unit Under Test) for self limiting current and protection.

[budm]

Tab bonding repair:
http://www.badcaps.net/forum/showthr...ht=tab+bonding
http://www.badcaps.net/forum/showthr...ht=tab+bonding
http://www.badcaps.net/forum/showthr...ht=tab+bonding

[budm]

What bad brown glue can do:
http://www.badcaps.net/forum/showthread.php?t=34692

[triplefour]

that Led string indicator looks really cool, but i cant tell exactly how to build it just from the pictures. could you draw a schematic and maybe explain a little? thanks!

[budm]

More info on T-CON and Panel failure.

[budm]

LED and power supply.

[daroo]

Thank you for this useful information.

[budm]

LCD panel disassemble to get to bad lamps assemblies, SAMSUNG 25" TV/MONITOR, also show how to verify if the lamps are bad using spare lamps.
This failed unit you can smell Ozone.

[budm]

Simplified operation of the TV:
So once you get the STBY to work, then you hook it up to the main board, if the main board is OK then when you hit the power switch, the main board should send the PS_ON (>2.5VDC, this signal is used to turn on the switched transistor to supply the VCC which is generated by the AUX winding of th STBY transformer to run the PFC controller IC and the SMPS IC) to turn on the PFC Voltage booster (the voltage on the cap should go up from 160VDC to >360DVC) and the 12V/24V SMPS section, after slight delayed it should send the BL_ON and diming control signals that are routed through the power supply for clean wiring to the inverter board to turn on the backlights, and at the same time the processor on the main board will send the T-CON on command to turn on the switched MOSFET which is used as a switch to supply the 12V (or 5V depends on the panel) to the T-CON board, that is the basic operation of the TV.