t23 xga screen - inverter killer? *PIC*

[Mace1]

Last week my T23 XGA screen suddenly began to flicker, then went black. I removed the inverter (could smell it had burned) and saw the last component on the inverter board just ahead of the backlight connector had burned.
The first inverter I ever had to change on this T23 went out two years ago, the same component had burned. Received a new converter today, installed it and 20 minutes later it too burned out, the same component on the inverter board had fried. The LCD worked fine, that is as long as the inverter works. The display was not dim or blinking prior the the inverter failure. Would the backlight cause this? Heres a photo of the last two inverters that failed.



Admin edit: Added PIC warning in subject line

[rkawakami]

Possibly, but what also could be happening is that the wiring to the backlight is either shorting together or is being disconnected from the backlight.

ref: http://forum.thinkpads.com/viewtopic.ph ... 03#p333603

[frankiepankie]

Are you using an original IBM AC Adapter? Maybe it spits out a voltage higher than the official 16V, and is that the reason your inverters keep burning up.

[Mace1]

I checked the backlight cable, the insulation is fine and where the wires go into the panel show no signs of ever being pulled through the cable outer sheathing. Also, I have always used the 16v - 4.5 amp IBM power adapter that came with the laptop. The recent problem reared it's ugly head last week after I removed the display to get rid of the wireless antennae I had duct taped to the inside of the lid. All the tiny display panel mounting screws are original, the same length so I'm sure they could not internally short the panel to the hinge arms.

[Mace1]

Also, I checked the power adapter, at no-load it holds at 16.7v. I'm going to buy another inverter, hopefully the last one was defective.

[Unknown_K]

Could be the backlight bulb is on the way out killing inverters. I have a T2x model with the 13.3" screen that killed inverters, the backlight bulb has one end that is black, I assume the internal wire is cracked causing hotspots and drawing more current then normal (the screen flashes when turned on with a good inverter then goes out).

A new inverter is cheap enough, but if the problem does not go away you will need a new screen (some 14" LCD panels are too much of a pain to rework).

[Mace1]

Uh,Huh. Under very close examination I discovered the connector on the end of the CCFL cable has one burned pin, it actually got hot enough to melt some of the plastic. I was not aware that no load on the inverter output could cause failure. I have no idea how to expose the backlight to see if it has a dark end.

[Unknown_K]

You would basically have to take the CFFL tube out to look, not recommended unless you know it is the problem and like to goof around. The 13.3" screen I took apart was easy to get to the bulb, on another 14.1" screen you basically had to take the whole thing apart.

You can probably find complete screen units for a T23 on ebay cheap, or maybe a whole unit. Few people would bother getting a new bulb for something that old.

[Mace1]

The display is working now! Applied a minute smear of silver conductive grease on the CCFL connector's pins with a toothpick. It's been working for 25 minutes now.

I'm happy as a rabbit in a carrot patch now!

[RealBlackStuff]

Doing that is only "delay of execution".
That CCFL needs to be replaced, with one like this below.
And look at the instructions given there over several pages: http://www.lcdparts.net/ccflDetail1.asp ... OVOIBM141R
I did a write-up on how-to, but that does not apply to the majority of the T23 LCDs. http://forum.thinkpads.com/viewtopic.php?f=31&t=88991

[Mace1]

RBS- Thanks for the links. I ordered a new CCFL this morning, hope the 9.99 shipping gets gets the new CCFL delivered in one piece. Could use some info on procedure involved in separating the LCD layers.

[RealBlackStuff]

Could use some info on procedure involved in separating the LCD layers.

That is the one thing you want to AVOID at all cost! Dust is an LCDs worst enemy.
Remove the metal frame around bottom and sides of the LCD.
Hold all layers together while you do this. Put scotch tape around the sides to keep the layers together.
Now try to remove the silicon covers at each end. Write down how they 'sit' so you can get them back in.
Once removed, unsolder the wires at each end of the CCFL, and replace CCFL with the new one.
Do NOT touch the tube itself, use a surgical glove or similar to handle it.
Reverse the above operations.

[Mace1]

UPDATE!!!
The new CCFL arrived today so not having anything better to do so I replaced the backlight. It was not hard to do, in fact it only took an hour but I spent an additional 4 hours locating 3 of the super tiny display frame screws that migrated into my carpet! In the final moments mounting the inverter (GRRR), I managed to pull one of the wires out of the two-prong plug that powers the backlight.
I don't give up easily so I soldered the wire to the inverter and on power-up I was very pleased to see the IBM post screen but that lasted only three or four seconds. Now the CCFL fires up but only stays on for a few seconds. I know the inverter that previously arced is bad and is now shutting down after a few seconds. Getting a new inverter is easy, getting another plug with pigtails attached is another matter. Might as well look for a junk T-2x on ebay. In the meantime I'm getting some use from the 15 inch monitor I use as a backup.