Cheers for the reply. I have no reason to suspect that Dell replaced the screen when they did the motherboard (they didn't tell me they had and if they did I'm sure they would have charged me!). However there is no real way of knowing if they have or not...
To me it just looks like they have left the screen displaying the Dell Diagnostics start menu all weekend, and it has somehow burnt this image into the display (but again I didn't think this was possible with LCD's?).
All in all I seem to have had every single component of the laptop replaced over the last year....the only thing that hasn't been replaced is the Dell logo on the lid (and I'd give anything to swwap that for a Sony or Compaq!)
I suspect that your LCD burn-in is the result of a "Old Lamp for New" situation. This is not base on fact but suspicion because I also have an Inspiron 8600 purchased about the same time and now my LCD is not functional. From web postings; the LCD backlight and/or inverter are very prone to failure...AND considering the outsourced "Dell Techincal Support" that can understand your problems outside of the scripted "technical help"; my guess as to your problem chronologically are as follows:
1. Your first instance of LCD problem; Dell probably replaced it with a refurbished one.
2. When you ran the "F12" reboot w/diagnostic; My belief is that the diagnostic doesn't tell you where the actual problem is.
3. Your last LCD problem: Dell probably switched the entire LCD assembly with another (used) one and therefore now you notice the burn-in whereas it didn't exist before. From what I could gather from the web and this forum; Hitachi and Samsumg were the major supplier for the Insipron during '04.
This reply doesn't really help you in anyway; but I just needed to vent. I truely appologize for this
Message Edited by cpm-buzzy on 09-12-2005 11:27 PM
LCD displays operate on a relatively low frequency alternating current (AC) squarewave which drives the backplane of the LCD and switches the thousands of pixels on and off. The AC waveform or backplane driver is generated by associated LCD driver circuitry. All LCD's have such circuitry or else the pixels would be unable to display an image. This has nothing to do with backlighting or the backlight inverter circuitry.
The backplane AC waveform causes the LCD pixels to switch on and off and to refresh themselves at a design frequency of let's say 50-100 hertz. When the AC squarewave is interrupted for an extended period of time while an image is on screen, the image will be permanently retained within each pixel as a "ghost" image because the pixels become permanently damaged.
This ghosting is caused by a steady state direct current (DC) applied to the LCD instead of the proper AC backplane waveform. The DC voltage is usually a result of either a failed backplane driver circuit or, as in the case of motherboard troubleshooting and replacement, an intentional or inadvertent interruption in voltages and/or signals being sent to the LCD driver circuitry. There are several easy ways for a tech to interrupt the backplane squarewave and quickly destroy an attached LCD.
The DC voltage applied to the LCD backplane either burns out the image-producing pixels or, in your case, permanently damages them so that they can no longer refresh completely, leaving this ghost image on your screen.
Thanks very much for that! I figured it must have been caused by some clumbsyness when it was being plugged in/out of the motherboard, so I appreciate the technical description of what may have caused it. I have the Dell technician coming round this afternoon to have a look and see whether they will take it back and fix (I'll make sure they will!).
Now I have the technical explanation they won't be able to fob me off and claim it was something I have done. I'll post back later to let you know if they agree to replace it free of charge.
jash_uk
1 Rookie
•
14 Posts
0
September 13th, 2005 03:00
Cheers for the reply. I have no reason to suspect that Dell replaced the screen when they did the motherboard (they didn't tell me they had and if they did I'm sure they would have charged me!). However there is no real way of knowing if they have or not...
To me it just looks like they have left the screen displaying the Dell Diagnostics start menu all weekend, and it has somehow burnt this image into the display (but again I didn't think this was possible with LCD's?).
All in all I seem to have had every single component of the laptop replaced over the last year....the only thing that hasn't been replaced is the Dell logo on the lid (and I'd give anything to swwap that for a Sony or Compaq!)
cpm-buzzy
8 Posts
0
September 13th, 2005 03:00
Hi Jash_UK:
I suspect that your LCD burn-in is the result of a "Old Lamp for New" situation. This is not base on fact but suspicion because I also have an Inspiron 8600 purchased about the same time and now my LCD is not functional. From web postings; the LCD backlight and/or inverter are very prone to failure...AND considering the outsourced "Dell Techincal Support" that can understand your problems outside of the scripted "technical help"; my guess as to your problem chronologically are as follows:
1. Your first instance of LCD problem; Dell probably replaced it with a refurbished one.
2. When you ran the "F12" reboot w/diagnostic; My belief is that the diagnostic doesn't tell you where the actual problem is.
3. Your last LCD problem: Dell probably switched the entire LCD assembly with another (used) one and therefore now you notice the burn-in whereas it didn't exist before. From what I could gather from the web and this forum; Hitachi and Samsumg were the major supplier for the Insipron during '04.
This reply doesn't really help you in anyway; but I just needed to vent. I truely appologize for this
Message Edited by cpm-buzzy on 09-12-2005 11:27 PM
asd34567
112 Posts
0
September 13th, 2005 11:00
Here's your scientific answer.......
LCD displays operate on a relatively low frequency alternating current (AC) squarewave which drives the backplane of the LCD and switches the thousands of pixels on and off. The AC waveform or backplane driver is generated by associated LCD driver circuitry. All LCD's have such circuitry or else the pixels would be unable to display an image. This has nothing to do with backlighting or the backlight inverter circuitry.
The backplane AC waveform causes the LCD pixels to switch on and off and to refresh themselves at a design frequency of let's say 50-100 hertz. When the AC squarewave is interrupted for an extended period of time while an image is on screen, the image will be permanently retained within each pixel as a "ghost" image because the pixels become permanently damaged.
This ghosting is caused by a steady state direct current (DC) applied to the LCD instead of the proper AC backplane waveform. The DC voltage is usually a result of either a failed backplane driver circuit or, as in the case of motherboard troubleshooting and replacement, an intentional or inadvertent interruption in voltages and/or signals being sent to the LCD driver circuitry. There are several easy ways for a tech to interrupt the backplane squarewave and quickly destroy an attached LCD.
The DC voltage applied to the LCD backplane either burns out the image-producing pixels or, in your case, permanently damages them so that they can no longer refresh completely, leaving this ghost image on your screen.
The only solution: replace the LCD display.
jash_uk
1 Rookie
•
14 Posts
0
September 14th, 2005 03:00
Thanks very much for that! I figured it must have been caused by some clumbsyness when it was being plugged in/out of the motherboard, so I appreciate the technical description of what may have caused it. I have the Dell technician coming round this afternoon to have a look and see whether they will take it back and fix (I'll make sure they will!).
Now I have the technical explanation they won't be able to fob me off and claim it was something I have done. I'll post back later to let you know if they agree to replace it free of charge.
Cheers again, I owe you a beer!