My gateway laptop just lost its lights on the display works well but no screen lights
On my laptop the light comes on and shuts down after about 6 seconds. It behaves exactly this way after whatever I do to engage it; turn the computer on, wake up from standby, press and release the "lid closed" detection pin, ...
There is a button on the keyboard with a light blue "Fn" on it. While holding it down I can adjust different settings such as illumination, contrast, etc.
I noticed at one occasion that pressing it right after engaging the light it shuts down prematurely (quicker than the 6 seconds I mentioned above).
So I tried to crank the illumination down and up to max (while the lights were "off"), press hold and release the "lid closed" pin and after a few attempts the lights came on and stayed on without shutting down again.
If the computer goes to standby or powersave or whatever that invokes it to shut down the display light I have to struggle this way again in order to revive it.
I also noticed that when adjusting the illumination, if I go below a certain threshold, the screen goes completely black. It seems like the lowest notches of the illumination control cannot supply enough voltage to run the display light although it doesn't show any signs of impairment once it starts working (e.g. abnormally weak light, yellowish color, flickering, ....).
Does anyone have any clue as to what is malfunctioning?
Run the PSA Diagnostics and Obtain the PSA Error Code
To run the PSA diagnostics and obtain the PSA error code, perform the following steps:
Shutdown the computer.
Press and hold the <Fn> key, then press and release the power button.
Release the <Fn> key when the lock lights above the keyboard begin to flash or Diagnostic boot selected is displayed in the upper right corner of the screen.
Release the <Fn> key.
The PSA diagnostics sequence begins.
After approximately 2 minutes the system produces a number of alert tones.
After the alert tones, the system produces either a series of low beeps or error codes.
Note:
PSA diagnostics will prompt for input during some tests. The resulting error message does not necessarily indicate hardware failure.
For example, input is required during the color bar test. Failure to input a response will eventually result in a timeout error: 1000-0333 Graphics test timed out waiting for keyboard response. This does not indicate a graphics failure has occurred.
Note the sequence of beeps or error codes.
Initialize LCD BIST Diagnostics
You can initialize the LCD Built-in Self Test (BIST) in two ways, depending on the revision of Pre-boot System Assessment (PSA) diagnostics:
PSA versions 3019 and greater run LCD BIST immediately after failing the color bar test, via user input of <N> or waiting for it to time out prior to generating the 3-3-3 or 3-3-4 error. PSA version 3019 became available in November 2005 on various Dell laptops. The PSA version is upgraded with the BIOS.
With older versions of PSA diagnostics prior to November 2005, LCD BIST runs after responding with a <Y> after receiving a 3-3-3 or 3-3-4 error code.
To initiate the LCD BIST on PSA versions 3019 and greater:
Boot to the PSA Diagnostics.
Watch the screen and listen for the color bar test prompt tones emitted by the PSA Diagnostics. If the screen is visible, one will see the PSA diagnostics draw a series of multi-colored bars across the screen. When completed, a prompt asking if the pattern was seen appears, accompanied by a brief series of tones.
Press <N> or wait approximately 30 seconds to fail the color bar test.
Watch for the LCD BIST color generation and listen for the beeps every 2 seconds that indicate LCD BIST is running.
LCD BIST runs for approximately 20 seconds, then stops. The 3-3-3 or 3-3-4 error code is then displayed when the LCD BIST is complete. If LCD BIST does not initialize, then the system may not have been upgraded to PSA version 3019.
To initiate LCD BIST on systems with PSA versions prior to 3019:
Boot to the PSA Diagnostics.
Watch the screen and listen for the color bar test prompt tones emitted by the PSA Diagnostics.
Press <N> or wait approximately 30 seconds to fail the color bar test.
The system emits a 3-3-3 or 3-3-4 PSA error after failing the color bar test. Wait for two iterations of the failure code and then press <Y>.
Note:
On a working LCD, the PSA diagnostics shows the following message:
Error Detected, continue testing? Yes or No or Retry.
Watch for the BIST color generation and listen for the single beeps that indicate LCD BIST is running.
Patterns of flashing color should appear on the screen. With every color change, an audible beep is heard. If the patterns of color do not appear, and the beeps are audible, an LCD failure may be the issue. If the patterns of color appear, a video card or motherboard failure may be the issue.
IF AN ERROR IS INDICATED, PLEASE CALL DELL SO YOU CAN SEND SYSTEM TO SERVICE DEPOT FOR REPAIR (WE'VE JUST TRIED TO ISOLATE ISSUE TO SEE IF ERROR IS CAUSED BY HARDWARE OR SOFTWARE, OR JUST SOME CONFIGURATIONS)
Thanks and Goood luck! =)
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Note that this problem does not interfere with any other functionality of the laptop. It runs like normal and if I have a strong lamp I can still use the computer when the light fails. There is no distortion whatsoever of the picture in the LCD screen when the light is out, no lag, no sluggishness.
I think this problem occurs because of one of the following reasons:
1. Faulty LCD lamp
2. Failing LCD inverter
3. Failing/oxidizing connections
4. Failing power supply circuitry (for the inverter and not the external PSU)
The question is which one it is.
I suspect that it is either (1) or (2).
The thing is that when it's on it's on, and when it's off it's off. There is nothing in-between, i.e. no distortions, abnormally weak light, tainted color/whiteness or flickering. If it was the lamp I would suspect that there would such signs as well. (Am I right ?)
The inverter is exposed to a lot of heat from its operation, it delivers high voltage and the power saving function inherent in Windows does expose it to a lot of thermal stress cooling it down and heating it up when it is turned on and off so I wouldn't be surprised that this might be starting to fail.
I ran the PSA tests you are mentioning but they are not helpful at all. The only thing they give me is whether or not there is something wrong with the display which we already have established. I'm not sure which version I have but I saw that it tested the presence of the LCD-inverter, it was there. This light problem is intermittent (i.e. it comes and goes) and the lights were working during the entire tests. Even the brightness tests were passed flawlessly (to my slight surprise).
My guess is that the lighting problem has gone away now when the circuitry has been on for a while and will come back again when they have cooled down. Perhaps this is a lamp issue although no other signs of ligh-malfunction mentioned above are showing up.
Another thing with the diagnostics software is that they usually don't pinpoint the where is the problem when a failure is indicated. For example let's say that the diagnostics indicate a failure on the gfx card. That doesn't mean that the gfx card is faulty, perhaps the card doesn't get enough power to run properly. If that's the case, a new gfx card will not solve the problem as the new card won't get enough power either. Common sense is of uttermost importance when using diagnostics software and the failure indications are merely starting points for a deeper investigation.
The problem is getting more and more intense and the duration between initiation and shutdown of the backlight is getting shorter. I couldn't manage to revive it and keep it on today as I did yesterday.
I have learned a bit more about CCFL lights and it turns out it works by the same principle as a regular fluorescent tube. The only major difference, apart from the phosphoric mixture is that it is primed by a high voltage instead of glowing filaments (and the tube is 2-3mm thin instead of 2-3cm).
Since the lamp shows no obvious indication of wear when it's on (red tint, dim or flicker) my suspicions are moving closer and closer to the inverter board.
I really hope that I won't have to replace the lamp. They are a pain in the a* to replace.
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