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Lg l1710 inverter board fault

Lg L1710s LCD monitor - inverter board fault ( backlight turns off after 3 secs , turning power on solves for a further 2 secs ) - any componet repair tips / advice and replacement part # information for faulty part /

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  • sargon001 May 01, 2008

    this store does not have the part , in either case i need to repair the board i have , can you help

  • sargon001 May 01, 2008

    the store does not have the part , in either case i would prefer to fix the existing inverter board

  • cancer45 Jan 21, 2009

    I have the exact same problem on a Sony Vaio VGC LS37E. The backlight stays on for 3 sec and then shuts off. Pressing the on/off switch adds another 3 seconds each time. Replace the inverter but the problem persists.

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May i know the model and the make of the product in details so that it can help me resolving the issue is a more prompt manner

Posted on May 01, 2008

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I have a gateway netbook and the screen turns white after startup. What can I do to fix it?


Sure wish I knew the exact Model Number of this netbook. It's on the bottom in a white Service Tag, or sticker.

All I can give you is generic information.

On the back of the netbook, or on one of the sides, is a VGA connector. (Perhaps even the front)

This is a basic example of a VGA cable, and a VGA connector, (To the right is the connector),

http://en.wikipedia.org/wiki/VGA_connector


Netbook OFF, monitor OFF, connect the VGA cable of the monitor to the VGA connector on the netbook.

You can use a CRT monitor that looks like a small TV, or an LCD flat screen monitor that has a VGA cable.

Turn the monitor on. IF it is a CRT monitor give it a few minutes to 'warm up'.
Turn the netbook on.

IF the display does not automatically come up on the external monitor, (The VGA monitor), press, and hold down on the Fn key, and at the same time tap once on the Display toggle-over key.

Again generic information;
The Fn key is usually located on the Keyboard near the CTRL key to the left.
I have no idea where your Display toggle-over key is.

This key will be one of the Function keys at the top of the keyboard. Either F1, F2, F3, F4, F5, F6, F7, and so on.

There should be a monitor symbol on this particular key. Will look like an empty rectangle with rounded corners. Supposed to represent a monitor. There may be an arrow to one side of it.

The arrow represents the display moving over.

Different laptops, (netbooks), have different options.
Usual is;
1) Just the internal monitor of the laptop
2) Internal monitor of the laptop, AND the external monitor
3) External monitor Only.

Do to there being more than one option, you may have to tap the Display toggle-over key more than once.

A) White screen also shows on external VGA monitor?
You have a bad graphics chipset.

For most laptops, and I'm betting with this netbook, the graphics chipset is soldered directly to the motherboard. This is Integrated Graphics.

Another term for Integrated Graphics is OnBoard Graphics.
ON the motherBOARD.

This would mean replacing the motherboard.

(IF the netbook does indeed have a graphics card, the card could be replaced, and not the motherboard)


B) Display on external VGA monitor is okay?
There is a problem with the Display Assembly.

Essentially, the entire upper half of the netbook, is the Display Assembly.

1) Display Cover: The plastic top cover of the netbook.
2) LCD screen
3) Display Bezel: The thin plastic frame in front of the LCD screen. Resembles a picture frame
4) Inverter (Screen Inverter)
5) Webcam (IF installed)
6) Brackets which hold the LCD screen to the Display Cover, LCD screen frame, Hinges, various screws, and so on.

Primer:
1) An LCD screen does not produce light. It needs an additional light source.
A Backlight is the additional light source.

A Backlight is a CCFL.
Cold Cathode Fluorescent Lamp. (Lamp = Bulb)
Similar to Fluorescent lighting used in homes, and businesses, but on a MUCH smaller scale,

This example is just to show you where one type of Backlight is located, and what an average Backlight looks like,

http://www.laptoprepair101.com/laptop/2007/12/09/replace-laptop-backlight-ccfl-lamp/

With a LOT of laptops, and probably this netbook, the general repair method for replacing a Backlight is to replace the LCD screen.

An LCD screen is composed of layers. These layers are held in place by the Display Frame. A thin metal frame which surrounds the outside edges of the LCD screen layers. Also resembles a picture frame.

As you can see from the above link, the Backlight is accessed by removing the Display Frame on one side, or all together. This allows the LCD screen layers to move around. They MUST be kept, or put back in the exact location they were in, as set by the factory.

This is why the general repair method is to replace the LCD screen, for those who do not possess the technical skill of replacing, OR the manufacturer does not offer just the Backlight bulb.
{LCD screen = $$$$$. Backlight bulb is usually around $15 to $30}

2) Inverter:
An Inverter converts the electricity from the laptop for the Backlight.
In 90 PERCENT of Display Assembly problems, the fault is the Inverter.

OR, it may just be a loose Video Cable, or Inverter Cable.
The connections may be loose.

This requires partially disassembling the netbook, down to the connection of the Video Cable TO the motherboard, to see if this connection is tight, and may also require disassembling the Display Assembly partway, to see if the connection of the Video Cable TO the LCD screen is tight.

{You cannot just eyeball the connections. They need to be physically checked to see if they are plugged in tightly}

Requires partial disassembly of the Display Assembly, to see if the connection TO the Inverter is tight, and FROM the Inverter to the Backlight is tight.

Connections prove to be tight, visually inspect the sheath of the Video Cable for obvious signs of damage. If the sheath is damaged, there is a good chance that one of the thin tiny wires inside it has become stretched, and is broken.

Obvious signs of damage, or not, I would suggest removing the Video Cable, and with a multimeter set to Ohms,(1K) check the continuity of the individual wires in the Video Cable.

Be sure the problem is not the Video Cable.

Video Cable proves to be good, replace the Inverter.

(Replacing an Inverter is a simple task, and the cost of the Inverter is economical enough to warrant this type of procedure, IMHO)

Still no satisfaction? Replace the LCD screen.

Post the Model Number in a Comment, and I'll make this solution more custom to THE netbook you have.

Regards,
joecoolvette

Oct 17, 2011 | Gateway Computers & Internet

Tip

Basic LCD Monitors troubleshooting guides


By Bud Martin
First if you can, try the monitor with other PC first to make sure it is not the PC problem.
Notes: We are dealing with high voltage that can kill you! so if you are not sure what you are doing, please have it fixed by the pro that has proper tools and safety equipment. Try to use GFI outlet and isolation transformer when work around the TV set and DO NOT DEFEAT THE GROUND PIN OF THE OUTLET/POWER CORD.

The monitor will have at least 2 circuits boards, one board will be the logic board where the video cable from PC is attached to, the second board used in most monitors today is the Power supply/backlight inverter board combinations. Some monitors will have separate power supply module and backlight inverter board.
The monitor should be connected to the running PC otherwise it will go into standby mode.
The operations of each board:

1) The Power supply board:
It takes the 120vac 60Hz and converts it to high voltage DC (around 160~170vdc filtered by the 80~150uf 250~450vdc cap) by the bridge rectifiers to be used by the switching power supply circuits that converts this DC voltage into high frequency (around 50~100 KHz) AC for driving the step down transformer. The outputs (usually 2 outputs) of the transformer will be rectified by the diodes to produce the regulated 5vdc for the logic board, and regulated 12~20vdc (12vdc is usually for screen up to 17inch, 16~24vdc for 18~24 inch screen).

The power supply circuits are always on (unless the monitor uses the power switch that actually disconnects the power from the outlet which is rarely used these days) which means that it is running 24/7 using the monitor or not, any spikes and surge will be fed into the monitor power supply.

Common problems:
Blown fuses, bad caps (leaking/bulging tops or bottom seals, please note that bad cap may look normal but it can have high ESR (Equivalent Series Resistance). The DC filter cap should be low ESR type for using in the switching power supply; general purpose electrolytic types will not last very long in switching power supply circuits. Poor solder joints, over heated components.

Testing:
Plug the monitor in but do not activate the power switch so the backlight inverter circuits will be off. Check the 5vdc and the 12~24vdc to make sure they are OK. They should be tested with the load, you can use 6V 1A (6watts) lamp for the 5vdc, and car lamps such as 1157 (12v 8watts lo/26watts high) turn signal brake lamp using high filament connection for testing the 12~18vdc (or use two 1157 in series for 19~24vdc) for the backlight inverter circuits.
If the power supplies are working, the output voltages should be steady at the rated voltages. The power supply will go into shut down if it detects too much current draw due to false in the power supply or short circuits in the backlight inverter or in the logic board.

2) The backlight inverter circuits:
It takes the 12~24vdc and converts it to high frequency AC to drive the inverter transformers CCFL (Cold Cathode Fluorescent Lamp) assemblies. The transformers will drive the CCFL by applying the start up voltage (around 1500~2000v), when the CCFL start conducting, the voltage will drop down to about 500~800v.
The inverter has detection circuits to detect open circuit if the lamp is not attached or does not fire up after the start up voltage is applied, it will go into shut down. It will also shut down if the lamps draw too much current due to ages (when lamp gets old it will draw more current).
The inverter gets two signals from the logic board, one is the backlight ON/OFF signal, the other one is the Dimming signal for the lamps.
Common problems:
Bad filter caps, resonant caps (in the inverter output circuits), blown transistors/IC, shorted or open transformer winding.
Testing:
You should have spare lamps for testing the inverter circuits.

3) Logic board:
The logic board get the signals from the VGA (ANALOG) or DVI (DIGITAL) and processes them and feed them to the LCD panel T-CON (Timing Controller) board on the back of the LCD panel.
It also sends out two signals (backlight ON/OFF and Dimming) to the inverter circuits when the monitor is on and getting the signals from the PC.
If the logic board does not get the signal from the PC, it will put monitor into standby mode.
The 5vdc feeding it is converted to 3.3v, 1.8vdc by the switching buck converters to run the processor.
The logic board also sends the 5vd or 12vdc power for the T-CON board, if the voltage is not there, you will see white/grey glowing screen only.
Not much repair you can do on the logic board unless you have the full service manual and surface mount repair station.

4) CCFL and Inverter circuits testing:
If you don not have the inverter and lamp tester boxes you may be able to do a simple test by using these steps:
If the screen flashes on for a second, you can disconnect all the lamp connectors and connect it into one of the transformer output connector and see if you will see the flash on the screen, if you do, then try it with another transformer output connector to see if it also get the flash on the screen.
Repeat the procedure with other 3 lamps. If all the lamps do flash on for seconds then more likely the lamps are OK. If lamp only flash on one of the transformer output then you will know that the problem in that transformer inverter circuits.
If none of the lamps flash at all then the problem is in the inverter circuits, power supply, or not getting the on signal from the logic board.

Bad caps
http://i.fixya.nethttp://i.fixya.nete17e9cc.jpg

Power supply/inverter board (L), Logic bd. (R)
http://i.fixya.nethttp://i.fixya.netbc19983.jpg'

Dead T-CON bd, blown fuse. Get glowing screen only.
http://i.fixya.nethttp://i.fixya.net4fbd9e1.jpg

T-CON board's fuse F101
http://i.fixya.nethttp://i.fixya.net8506e44.jpg

Inverter board surface mounted fuses, F1 and F2

http://i.fixya.nethttp://i.fixya.net1bf6596.jpg
Bad lamps (Blackened ends, burnt /poor soldering)

http://i.fixya.nethttp://i.fixya.net5c8952e.jpg

http://i.fixya.nethttp://i.fixya.net4e5e9a1.jpg

Bad LCD panel (solid vertical lines)

http://i.fixya.nethttp://i.fixya.netffe90fe.jpg

Bad LCD panel due to bad T-CON board
http://i.fixya.nethttp://i.fixya.netef48b18.jpg
Failed TV and Monitors:
http://s807.photobucket.com/albums/yy352/budm
http://en.wikipedia.org/wiki/Capacitor_plague
Make your own test lamps: http://www.badcaps.net/forum/showthread.php?t=19987

on Sep 25, 2010 | Computers & Internet

1 Answer

Please i don't know what wrong wit LCD monitor


Could be a bad inverter board or LCD backlight. Please refer to the following article for more details:
http://www.fixya.com/support/r6430776-troubleshooting_laptop_power_failures

Jun 20, 2011 | Acer Computers & Internet

1 Answer

Hi guys! Im having problem with my Dell monitor. When i turn on my computer it will load but my monitor just display 2-3 seconds and it will turn black again..the power light is working when i turn off and...


This is a problem with the CCFL bulb (the back light) or the inverter that powers it. This bulb is inside the lcd pannle and requires great care to replace. Some local PC Repair shops will be able to fix it however most will not. The inverter which is (most likely) the problem can be found on ebay for $20-30 USD and is easily replaceable it is general a small curcit board below the lcd pannle hidden in the bevel. However same times the board is merged into a much larger board which will be tricky to replace as it is specific to the monitor.

Don't forget to rate below.

May 10, 2011 | Computers & Internet

1 Answer

Monitor goes black on screen while using The only ay to bring it back up is to turn it off and back on


There is a problem with the backlight controller inside the monitor. It may be due to bad capacitors or the inverter transformer may be faulty. Bad capacitors can be replaced or you can replace the backlight inverter board with a universal inverter board if you have some electronics knowledge.

Mar 01, 2011 | Computers & Internet

1 Answer

I have a hp laptop. was on line and screen went black. and will not show again. it strats up sounds but black screen.what do i do


1) Do you have a VGA monitor that you can use for an external monitor?
{VGA monitor is also referred to as a CRT monitor. Looks like a small TV}

The back of the laptop, or side, has a VGA port. The VGA monitor is plugged into it.
{Laptop off}
Then the VGA monitor is turned on, and allowed to 'come to life'.

Now turn on the laptop. Press the Fn key down on the keyboard, and hold it down.
Now press the Monitor toggle over key.
Since you did not state the HP laptop Model Name, and Model Number, I can only give you generic guidance on this.

The monitor toggle over key has a monitor screen symbol on it. It will be one of the F keys.

(It's an External Monitor toggle key.
Press it one time and the display toggles over to an external monitor.
Press it again, and both the laptop LCD screen, and the external monitor have a display on them.
Press it once more, and the display goes back to the laptop's LCD screen )

If display shows up on the external monitor, you have a problem with the display of the laptop.

Primer:
An LCD screen cannot produce enough light by itself. It needs an additional light source.
A Backlight is used as an additional light source.

A Backlight is a CCFL.
Cold Cathode Fluorescent Lamp {Bulb}
Similar to the fluorescent lighting used in homes and businesses, but on a MUCH smaller scale.

{Average Backlight is 3 to 5 inches long, and half the diameter of a No.2 pencil.
The Backlight is located on one edge of the LCD screen}

An Inverter is used to provide power for the LCD screen, and the Backlight.

90 percent of the time the problem is the Inverter.

Inverters are relatively cheap, and if I knew the Model Name, and Model Number of your HP laptop, I could give you a link to HP Support where you could download the Service Manual for free.

This way you would have a manual to show, and detail how to replace the Inverter, and I could guide you.

I could also give links for your perusal for Inverters.

There is one more thing however.

HP Pavilion DV2000, DV6000, and DV9000 series laptops, have a graphics chip overheating problem.
The laptop comes on, the blue indicator LED lights light up, but the LCD screen is black.

This video explains why, shows a solution to fixing the problem, and details out a lot more than I am privileged to state here,

http://www.youtube.com/watch?v=bnkQNmKauEc

Have further questions regarding any of the above, please state in a Comment.
(Believe upper right of your page)

Regards,
joecoolvette

Dec 02, 2010 | Computers & Internet

1 Answer

My lcd desktop monitor only displays a black screen and the green power light on it flashes, what can do to solve this?


The power board that distributes power throughout the monitor has died, this component is a circuit board that is inside the case and powers the inverters for the backlight as well as other components. You will have to find a vendor to supply this part to repair the monitor.

Jan 21, 2010 | Computers & Internet

1 Answer

Hello, I have a viewsonic 19 inch LCD panel. When I turn it on, the screen just goes black after 3 seconds.Whats wrong?


Hi there. It's probably your backlight inverter that has gone bad. What model is it ? The inverter can be on a seperate board, or on the main board on that viewsonic LCD. Is it a VX922 ? Common problem on these..

Nov 26, 2008 | Computers & Internet

2 Answers

Php-x19w keeps switching off after a few minutes


I've just spent ages tracking this one down. In my case it is the protection circuit in the backlight invertor. The tubes are worn out (they are pink when they first come on) and need replacing :((.
If the picture disappears and the blue light in the ON switch stays on, you've probably got the same trouble.

Oct 22, 2008 | Computers & Internet

1 Answer

Monitor goes black but the green light stays on. I turn the power button off and then back on and it comes back on. It may stay on for a few seconds to several minutes.


Check to see if the image is Dimmed. Chances are the power supply on the FPD is either dead or not supplying power to the back lights.

Your problem is the back lights are not being powered. There is a signal going to your FPD because the power light remains on green, but the back lights are what helps support an image from the Front Panel Display.
The only way to fix this is to open it up.

If its got 3 boards inside((logic-->video, Inverter, Power)) The problem is the Inverter. Replace it.
The inverter is the board that supplies power for the backlights to turn on. The backlights
provide a light.for the LCD Panel(provides color and is the logic. ... similar to a projector.
If its got 2 boards inside ((Logic-->video, Power)) The problem is the power supply. The inverter is embedded onto it.

Simply replace the part with a known good one, and you got a spanking new monitor.

Sep 18, 2008 | Computers & Internet

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