Shared Knowledge
“Pink Tinge LCD and
Backlight Replacement”
19 September 2005
Updated 20 October 2006
Several years ago my wife wanted a laptop and so we went out and bought a new Hewlett Packard (HP) N5190, which is an Intel 877MHZ, 14.1 inch TFT LCD model. She had the laptop for maybe 2 months at the most when every time she turned the laptop on, the LCD screen would have a pink tinge to it in the lower left corner, right above the laptop on\off button. The screen was not pink enough not to use it but it was obviously not right either, so we returned the laptop where we bought it and had it repaired under warranty. Of course when we picked up the repaired laptop, we were not informed as to the cause of the problem and what was done to fix it.
Recently, one day, out of nowhere, when she turned on the laptop, the LCD screen had the pink tinge back again, only this time, almost half the screen was pink. Ok, with the laptop out of warranty, time to figure out the problem and see what it would cost to repair.
First of all, a check of HP’s Internet parts store revealed that a new LCD module for the N5190 was $900, which is totally ridiculous as you can buy a used complete N5190 on eBay for $350 or maybe less. I then began an Internet search for the cause of the pink tinge and came across information, which said it is caused by a bum LCD backlight. Ok, and a backlight is? A light tube, which is usually at the bottom of the LCD, which actually provides the light of the LCD: not the data presented on the screen, just the light behind the characters or images.
So where do I go to get the backlight replaced? Again an Internet check revealed that I could either send the LCD to any one of several different companies and have them replace the backlight or I could buy the backlight and replace it myself. After reading that the backlight tube is simply slipped into a hole, slot, in the bottom of the LCD, I looked at the LCD I had and sure enough, quickly and easily removed the bum backlight. I then inserted the new backlight tube and associated metal reflector, reassembled the screen assembly, attached the screen assembly to the laptop body and was up and running with a repaired screen. Cost to repair pink tinge LCD? $39.
Ok, so it was not quite that simple as you have to get at the LCD, which means taking the screen assembly off the laptop and then removing the bezel surrounding the LCD and finally removing the LCD from the metal mounting hardware of the screen assembly but honestly it is not that hard and an Internet search should provide information on taking your laptop apart or at least getting the screen assembly apart.
20 October 2006 Update
After I wrote the above, I have now replaced the backlight in 6 or 7 HP laptop LCD's and it has turned out that replacing a backlight can be a real hassle and I suggest you first try to get a local repair done before attempting it yourself. The reasons I say this are: (1) the dam Cold Compact Fluorescent Lamps (CCFL) or backlights are so fragile, it is easy to break them in the process of installing or soldering to it; (2) Although soldering wires to the backlight is not such a big deal, getting the ends of the tube properly insulated such that the ends do not short out against the metal frame of the LCD can be a very big hassle and if you do short the tube to the case, when you apply power, you will burn out the LCD inverter board which is another $40 or so when you can find them.
My current method of replacing backlights is to use basically what is wire-wrap wire (very, very thin wire) and solder on a along piece to each of the connector wires associated with the backlight. I then use heat shrink tubing to completely insulate the wire-wrap, existing wire, junction. I then solder the wire-wrap wires to the ends of the CCFL, not right where the glass of the lamp starts but close, cutting off the excess wire of the lamp. I then use liquid electrical tape and coat both ends of the tube making sure that the soldered wires are completely insulated. I then reinsert the tube and surrounding metal shield into the LCD, reattach all surrounding metal and then using very small pins, using a voltmeter, determine if the backlight is shorted to the metal trim around the LCD or not. If shorted, take all apart and find source of short.
As I said, handling CCFL's has to be done gently or you are going to break them at the end or crack them in the middle somewhere.
If you are going to try this at home, I would suggest you buy 2 CCFL's as you might need the second after you screw-up the first.