I am working on LG 55LM4600-UC and LED backlight shuts down after a few seconds. Audio normal. LED on main board EAY62512801 blinks three times and stops and than repeats. Checked main electrolytic caps and they are okay. Since I am not very familiar with this model, could I get some troubleshooting tips. Thanks! Mike
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Re: LG 55LM4600-UC Backlight Shuts Down
Done any research on testing the Led voltages ?Please Do Not PM My Page Asking For Help Badcaps Is The Place For Advise, Page Linked For Business Reasons Only. Anyone Doing So Will Be Banned Instantly !
https://www.facebook.com/Telford-Tel...7894576335359/ -
Re: LG 55LM4600-UC Backlight Shuts Down
This video may give you a idea how to check the led voltages etc if have have problems post a picture of the led connector area of the power supply then we maybe able to tell you what pins etc to test. What power supply does this set use?
https://www.youtube.com/watch?v=Bf5T2wwtydYLast edited by vinceroger69; 11-23-2016, 12:36 PM.Comment
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Re: LG 55LM4600-UC Backlight Shuts Down
The LED+ voltage to ground is 78 volts than drops to 71 volts after backlight shuts down. While the backlights are lit for about 5 seconds, the V1, V3, V5...are about 8.7 volts to ground. After backlight shuts down the voltage is about 20 volts to ground. With LED sockets removed the voltage is about 102 volts to ground at LED+. Thanks for your help.Attached FilesComment
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Re: LG 55LM4600-UC Backlight Shuts Down
I have the service manual for 55LM4600; however, does anyone know how that I can get the power section schematic? Thanks, MikeComment
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Re: LG 55LM4600-UC Backlight Shuts Down
You need to find out if the BL-ON and the DIM control signals are still present or not when the backlights drop out.
This TV has 12 strings of LEDs, the Vxx pins are for the Cathode retun lines for the LED strings.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Re: LG 55LM4600-UC Backlight Shuts Down
Here are additional voltage information; I am assuming that I have a bad LED on string 6.
Voltages for each LED String measured at board pins (volt to ground):
Backlight on..........Backlight off
LED+ 78.8.............71.3
VC 1 8.4..............19.8
VC 2 8.2..............19.5
VC 3 8.6..............19.6
VC 4 7.7..............19.7
VC 5 8.4..............20
VC 6 1.3..............24
VC 7 8.6..............19.9
VC 8 8.4..............19.9
VC 9 8.6..............20
VC 10 8.6..............20
VC 11 8.4..............20
VC 12 8.9..............20Comment
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this tv is throwing me for a loop. do samsung tvs no longer have the backlight self test feature built into the power supply?
i tested the backlight with my LED tester and it lights up both strips. one of them reads 100v and the other reads 63.7v.
unplugged mainboard from power supply but left backlight plugged in, and then plugged psu wall power in. expected to see backlights light up but see nothing.
according to how ive diagnosed in the past, this would almost always be a bad power supply. replacement power supply was cheap like 20$ from ebay. but still i get not even... -
Good morning forum. , This notebook has problems with the backlight being absent. If I shine a flashlight on the screen, i can see the image. I tried to change several LCDs but the same problem. When I disassembled it, I noticed the LVDS connector was a little burned in the backlight pins. I also found oxide in the LVDS connector on the motherboard. I replaced the LVDS cable, same defect. I replaced the LVDS connector on the motherboard, same problem. I took some measurements on the pins (I used the boardview of the X580VD).
pin 36,37,38,39 19,40v
pin 35 no connected
pin... -
I bought this p2210f dell monitor to fix. Schematic is the same as p2210.
Behaviour is that monitors comes on but then backlight switches off almost instantly. If I look with flashlight I can still find the "No signal message". So definitely a backlight issue. Trying to advance the issue I proved that the protection circuit is switching off the backlight by shorting out C3 and resistor to disable the INL chip then re enable by removing the short.
This is where it gets interesting. When I disassembled the monitor to solder leads on c3 capacitor I noticed the backlight flickered... -
I suppose the real question is whether the existing pinouts from ether a 17IPS71 psu are cross compatible with a 17IPS12 psu? If they are then the exchange of the main boards should have no issues providing the screen is compatible with both main boards. Obviously you can change the screen configurations easily enough (providing you have the correct files) for the main board. Why may you ask would I do this? Well a lot of the smart features are no longer working on a Hitachi 48HBT62U main board I wish to give it a new lease of life!
Obviously the same LVDS connector for the screen connection... -
Hello all,
Am trying to figure out this backlight issue with this A1990 Macbook Pro.
Tests performed:
There is no backlight even with a good screen.
Backlight IC is receiving the correct support voltages.
Fuse F8400 ok
Current sense resistor R8400 ok
Backlight IC is receiving 3.3V on enable pin.
Backlight IC receiving voltage from PPBUS_G3H, aprox 12.5V.
Backlight IC receiving 5V from PP5V_G3S
Backlight IC BKLT_SCL and BKLT_SDA both measure 0.545V diode mode to ground
I2C_BKLT_SCL and I2C_BKLT_SDA both measure...
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