LG 42LG50 no backlight or display
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Re: LG 42LG50 no backlight or display
Find out if you do have 12VDC on both end so of the SMD fuse on the T-CON board with ref. to chassis GND.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 42LG50 no backlight or display
OK, try having one ribbon cable between the LCD panel and the T-con board connected one at a time to see what you will get on the screen.
Right now without that cable between the T-CON and the Master inverter board connected, do you still have full control of the TV, I.E. able to turn TV on and off?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 42LG50 no backlight or display
OK, try having one ribbon cable between the LCD panel and the T-con board connected one at a time to see what you will get on the screen.
Right now without that cable between the T-CON and the Master inverter board connected, do you still have full control of the TV, I.E. able to turn TV on and off?
Yes, I can now turn the power on and off via the power button on the front bezel.Comment
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Re: LG 42LG50 no backlight or display
OK, try having one ribbon cable between the LCD panel and the T-con board connected one at a time to see what you will get on the screen.
Right now without that cable between the T-CON and the Master inverter board connected, do you still have full control of the TV, I.E. able to turn TV on and off?------------signature starts here------------
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Re: LG 42LG50 no backlight or display
Be sure to cycle power off whenever disconnecting or reconnecting the ribbon cables. I fried a 60" Sharp panel like that once. Additionally, if you removed each ribbon cable, but didn't cycle the power when doing so, then repeat that process, cycling power as I just described, and you may get different results.Comment
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Re: LG 42LG50 no backlight or display
Well, we need to check the Voltages on the test points on the T-CON board next.
You can see bare copper pads with label for each one, so far I can see:
VD33V
V25V
VDD,
VGH
VGL
VAA
so look for pad with V????.............Last edited by budm; 07-17-2018, 10:05 PM.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 42LG50 no backlight or display
GND 0
SDA 3.3
VIN 12.44
SCL 3.3
TSTPGW 0
DRL1 0
OE1 3.3
STV 0
CKV 0
VSCN 0
VDD 3.3
VDA 0
VCOM 0
VGH 11.06
VGL -5.57
VST -0.18
SIN1 0
SIN2 0
GRL2 3.3
B_STH 3.3
B_TP1 0 (NOTE: when the ribbon cable from the master inverter is plugged in, this is 2.22v)
B_STHR 0 (rising slowly)
DIM_O 0
DIM_I 0.1 (rising slowly) (NOTE: when the ribbon cable from the master inverter is plugged in, this is 3.33v, even when the ribbon cable is disconnected if I test the pin on the inverter side it is 3.4v)
VD33V 3.3
VGHP 11.1
VAA 0
V12V 12.44
V25V_A 2.49
VREF 0Comment
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Re: LG 42LG50 no backlight or display
https://www.badcaps.net/forum/showpo...6&postcount=18
Some of the Voltages are low and some are missing, I.E. Vref. should not be 0V.
A this point you can try new T-CON board.
From Andrew in the link above:
1. Vin: 12V (we confirmed as present)
2. Vdd (Vlogic, Vddd): 3.3V
3. Vda (Vs, Vsource, Vdda Avdd): 14V to 20V
4. Vgh (Vgon, Von, Vddg): 20V to 30V
5. Vgl (Vgoff, Voff, Veeg): -5V to -7VNever 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 42LG50 no backlight or display
Received the new T-Con today.
No joy. Same exact results (same behavior, same voltages) with the new T-Con. So...main board? Is VDA on the T-Con supplied by the main board (over the LVDS cable)? If so, a bad main board would explain lack of VDA on the T-Con and the error signal sent to the inverters. And maybe the error signal sent to the inverter would also explain why DIM_I on T-Con, which is coming from DIM_O on the master inverter, is also high. Example: Main board is bad. It doesn't send the proper voltages to T-Con. It does send ERROR to master inverter. Inverter sends DIM_O high to T-con to indicate the error. Maybe? I don't know...thoughts?Last edited by Daveleone; 07-21-2018, 04:45 PM.Comment
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Re: LG 42LG50 no backlight or display
So do you get the same readings as in post 30?
What is the LCD panel model number?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 42LG50 no backlight or display
The panel has the following labels on it: "M$44-D024408 - L$T13A423068433524" and "V420H1-L12 Rev. C1 - C4C140185120364 - E207943"Comment
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Re: LG 42LG50 no backlight or display
Can you inspect the blue polymer caps on the psu next to the transformers on the bottom left hand side? Look for any signs of damage.Comment
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Re: LG 42LG50 no backlight or display
I am beginning to wonder if your Panel is bad now that I've read all the posts again.Comment
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