I have an LG LED tv here that has standby voltage, and upon pressing the power button the LEDs blink on and off every few seconds. Even when the LEDs are off the display can still vaguely be seen. The voltage at the LED connector fluctuates
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Re: LB5550 Backlight blinks
We need to see the pictures of the whole back side of the TV showing all the boards.
We also need to see the Voltage readings of all the pin at the connector of the power supply board that goes to the main board, also the Voltage readings of all the pins of the LED connector.
You MUST put down the pin name and follow by the Voltage reading for each pin, giving just the Voltage reading without the pin name will be useless.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=24809 -
Re: LB5550 Backlight blinks
LED connector has voltage fluctuating as stated before,
itsjust 4 pin LED + - + -
main board connector is as follows
GND - 0V GND - 0V
12V - 12V NC - 0V
12V - 12V 12V - 12V
GND - 0V GND - 0V
24V - 24V 24V - 24V
GND - 0V P-DIM2 - 1.2V
3.5V - 3.5V 3.5V - 3.5V
3.5V - 3.5V P-Dim1 - 1.2V
PWR-ON - 3.3V DRV-ON - 3.3VAttached FilesComment
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Re: LB5550 Backlight blinks
i also tried it with the main board unplugged and the LEDs still blinked.Comment
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Last edited by budm; 06-11-2018, 12:54 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: LB5550 Backlight blinks
pin 1: 25-30
pin 2: 102-125
pin 3: 102-155
pin 4: 230-260
as best as i could get themAttached FilesComment
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Re: LB5550 Backlight blinks
TV full model number is 55LB5500?
What is the LCD panel model number?
Shop jimmy version 1.0 Power supply board: LG EAY63072101 Power Supply / LED Board, http://www.shopjimmy.com/lg-eay63072...-led-board.htm.
Can we see straight shot pictures of the whole top and the bottom side of your? I cannot use the pictures from shopjimmy because PCB version is 1.0, your board is 2.1.Last edited by budm; 06-11-2018, 01:58 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: LB5550 Backlight blinks
yes thats the full modelAttached FilesComment
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Re: LB5550 Backlight blinks
LCD panel model number?
I need to verify the LED strips being used, so far all I know that it has two LED strings with two driver circuits with two different Voltages outputs (145V and 218V as printed on the board Version 1 and also on your board).
So based on your readings, they do not look right and point o bad LEDs.Last edited by budm; 06-11-2018, 02:01 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: LB5550 Backlight blinks
i appreciate you posting your thought process, its actually very helpful for me. I will get the panel number as soon as i can. might be tomorrow though.Comment
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Re: LB5550 Backlight blinks
here's what i gotAttached FilesComment
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Re: LB5550 Backlight blinks
Model LC550DUE (FG) (A6).
I will look up the spec. sheet to get the LED info.
I still need the high res picture of the bottom side of the board to verify the LED driver circuits and how the LEDs are connected.
BTW, do you LED tester? Something similar to this: http://www.shopjimmy.com/sid-gj2c-le...ght-tester.htmNever 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: LB5550 Backlight blinks
i do have the LED tester from ShopJimmy, i will test them now and also get a pic of the board.Comment
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Re: LB5550 Backlight blinks
here's the bottom of the PSU
can you talk me through what exactly you're looking for?Attached FilesComment
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Re: LB5550 Backlight blinks
I am checking to make sure that there are two LED strings driven by two LED driver circuits, which they are.
So what does the LED tester meter show for each string of the LED?
The LED string connected to pin 3 and 4 look to be where the problem is.Last edited by budm; 06-12-2018, 09:22 AM.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: LB5550 Backlight blinks
tester showed 200v at pin 3,4 and 100v at pin 1,2Comment
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Re: LB5550 Backlight blinks
can you point out to me where you see the two LED strings and drivers?Comment
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Re: LB5550 Backlight blinks
You have TWO LED + and TWO LED -, as you look at the bottom side, then you can easily see how each LED string is connected to the driver circuits.
See the two surface mounted MOSFETs close to the LED connector? Each LED - is connected to the Drain of the MOSFET, the Source is connected to the current sensing resistor and then to GND.
There are two Voltage boost converter circuits for each LED string that feed each LED +.
Get the P/N of that SMD IC close to the MOSFET to get the spec. sheet then you will see how it works.
The LED string that show 200V withe tester which only putting out around 20 ~ 30mA, at 400mA the Vf of the LED string will be much higher than 200V, LED power supply for that string is rated at 218V.Last edited by budm; 06-12-2018, 09:54 AM.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: LB5550 Backlight blinks
these are what you're talking about, correct? i'm gonna pull up data sheets for these and try to learn somethingAttached FilesComment
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Re: LB5550 Backlight blinks
https://www.badcaps.net/forum/attach...1&d=1528819719
I cannot read the p/n on the top line.
BD???????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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Vizio e601i-A3 - Has Sound and Display, But No Backlight - Bad Power Supply Board or Bad LED Bulbs ?I was given this TV from my great uncle. He said it just wouldn't turn on one day out of nowhere, replaced the TV, and gave it to me to possibly fix and use for myself.
Upon bringing it home and plugging it up, it showed a standby light.
I powered it on and without a flashlight, the display showed the "V" but the lighting is very dim, but visible.
The screen seems to blackout and stay black, but with a flashlight I can see the display.
With my Playstation 4 connected via HDMI, and running a game I can hear sound.
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Hello,
I am currently troubleshooting an LG 60UH8500 TV (2016 TV). Any help or suggestions would be appreciated.
Overall Issue: When TV is turned on, backlights all come on for about 10 seconds, then all go out. There is sound and there is a picture on the display (obviously hard to see without backlights, but it is there).
What I Have Done So Far: 1) Removed the back TV cover to expose the boards (Power Supply, Tcon, and Main), 2) blew out any dust and cleaned all connections, 3) Noticed that the LED backlights are fed from two separate connectors... -
This set has the known reputation of failed led backlights. The set does not turn on, but when plugged in, the power led stays lit for about 5 seconds followed by two short blinks and then it repeats itself. While shinning a flashlight on the screen, you can make out the Sharp logo, then it goes out and repeats the cycle. I measured some voltages across the led backlight connector. What has me puzzled is that when I place the negative lead of my vom on the led backlight pin connector (in which the black wire going to the leds was), I measure as high as -228volts, and then it falls to -95 volts... -
Hi. Recently serviced a damaged A1466 Macbook Air. Thought to post the issues and resolution for each.
Macbook AIR Model A1466 Diagnostic 09-01-2021
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Problems & Resolutions
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Problem
This is an LG edge LED lit LCD Display. The LEDs are on the bottom edge of the display. There are 2 bars (left and right) Each bar has many LEDs and a 6 pin connector. Each pin drive several LEDs thus is the highest current flow / heat junction. The weak lead free solder gradually fails with thermal expansion/contraction cycling and increases resistance. PSU will compensate up to a point, then when the current is too high, PSU just shut down the backlight causing a dark display. I have even seen one which the connector just fell off as solder points became completely detached....
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