After we drove this monitor 100 miles, it no longer has a working light. how can I determine if the fault lies with the inverter or with the bulb itself? would you please email me your answer at email@example.com. I asked a question earlier and something came back in a file format that my PC can't handle. thanks in advance, roger
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Re: backlight does not light
If I may add:
1. Your PC & display are both OK;
2. You need to determine which is at fault, the CCFLamp or the Inverter:
2.1 If the inverter is working, you would be able to read a high
frequency high voltage at the terminal connector that goes to the lamp,
if yes then it is the lamp (use a DVM set to AC 1K);
2.2 If no, then you need to check if the inverter is getting +12. If
yes, inverter is defective, if no then power supply is in question.
Offhand, I would suspect simply a loose connection somewhere
(considering that it was transported. Wiggle all connectors to make
sure they are snug and tight.). The next suspect would be the lamp.
They have a tendency to burn their ends/connectors or develop corrosion
over time which would manifest when jarred.
Hope that this be of additional help/idea. Pls post back how things turned out or should you need additional information.
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Re: backlight does not light
Sorry you are having this trouble these lcd monitors when you can still see your desck top but no light comes on then you might have blown a fuse inside the monitor the inverter is fine you have problems in the dc to ac converter in the monitor it self . how long have you had this monitor. you can take it apart and check for your self it is very easy all lcds no mater how big or small have a ac-dc converter in them small serface mount fuses that look like resistors go out also bad connections . when you take it apart you will see that the lamps are built in to the screen it is more costly to replace the lamps than to replace the monitor. get back to me and ill give you step by step to find the fusess. good luck
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This could be many things
Check all connections.
try a different known-good monitor with same video source (computer), if the second works then the fault lies in first monitor.
If the second monitor does not appear to work, the fault lies with your video source (computer).
In the former case, check power is going to the original monitor. Is the power light coming on ?
Without further information, it not possible to say much more
I have been looking at a Dell E228WFP with the same fault as previous posters on this forum. It works for a few minutes and then the back light turns off. With the PCBs out of the case it runs for a little longer. Applying heat to the inverter board using a hair dryer causes it to turn off in about 5 seconds. If you are after a quick test to see if your monitor is suffering from the R821 'resistor problem' then simply remove R820 (labelled 564), power up the monitor and heat the inverter board with the hair dryer. If it no longer turns off then R821 is probably your problem. I have shown the relevant section of the schematic below. I have not had a chance to make appropriate measurements to determine a suitable replacement value for R821. Reducing it from 1M to 560K or 470K will certainly lower the error voltage being fed back to IC801. If anyone wanted to determine a suitable value empirically then I would suggest replacing R821 with a 470K resistor in series with a small 500K preset and determining the highest value that allows it to operate correctly when heated. I would then back this value off by about 10% and fit the nearest fixed value 0603 SMT resistor. I have now carried out the above and R821 needs to be 470k to ensure reliable operation. If I had more time I would look into why this change is required....
Sounds like your backlight has gone faulty, this is a pretty easy repair, however it can be either the inverter, the power supply, or the lamp itself. You really need a service manual, to see how to do it and troubleshoot, exactly locate your fault. Otherwise,all one can do, is swap out, know good for bad, starting with the Power Supply, and working back, as if PSU isn't working 100% nothing else can do.
Hi first thing to do here is to see where the problem lies. use a vga / monitor lead from your laptop to an external monitor or lcd/plasma tv in pc mode and by pressing fn and your monitor switch key think its f5 you should be able to determine if your screen is at fault, a common problem is the screens inverter or backlight bulb, if you manage to get an image on your external source then you its sure to be screen related wether it be the inverter/backlight/or even your internal screen lead this process can save money and time, you would then need to test the inverter to see if its this, the inverter is normally the cheaper option as the backlight can be a long tricky process.
It's the backlight supply tripping out from backlight failure, but the thing still stays on. I got it to act right by switching to factory presets with some fast menu action once, but the general solution is going to involve tricking the backlight into staying on; you can look at the thing in bright ambient light to see that the display is still working, but of course without a backlight it's pretty much useless.
Since $100 buys a better and more efficient monitor, just replace it; otherwise of course you can either replace the backlight (or go for one of the projector mods) or convince its drive circuit to put up with it a bit longer. I spotted a bad capacitor but swapping that out hasn't gone well yet....
To determine if you have a video card problem or the LCD screen is at fault.
Connect an external monitor to the video port on the laptop and boot up your laptop, if you get a display on the external monitor then your video card is OK and you have a faulty LCD.
When you power your laptop without an external monitor and have a close look at the LCD screen at and you see a slight image then the fault is with the backlighting panel. This fault could be a faulty inverter or a faulty CCFL backlight lamp.
Defective CCFL backlight may has the following symptom:
Screen flashs on red/pink and off.
Picture stays on in red and slowly be come normal.
Picture flickering with dim display.
Picture flickering on and off.
The inverter can be easily replaced so can the CCFL lamp (but requires a lot more work)
For info on parts and repair service goto www.lcdparts.net
hi, i have had the privilege of work on these particular series of HP Laptops. This may sound daft, but have you tried the brightness keys? If so you have a fault with the backlight which is caused by 1) a fault on the Mainboard 2) the inverter has blown (a small circuit board the regulates the voltage from main board to the lcd screen) 3) The backlight on the lcd screen has blown. You will need to determine where the fault lies before paying out large sums. You may want to get a diagnostic done by a Local laptop company. Hope this helps.
Test your monitor. To do this, you will need another monitor.
Plug in any desktop monitor to the output port on the back of the laptop. Restart the laptop.
If you are able to use the laptop using this other monitor, then your problem lies in a part called a video power inverter.
It is possible that it could be the lcd backlight, but that is doubtful.
The power inverter is available at many online markets for a relatively small cost. Installation is generally easy enough that any person with reasonable mechanical skills and a set of small screwdrivers can do it.
I once walked an 11 year old boy through the process from 1200 miles away over the telephone.