IBM Thinkpad - Backlight screen black.. inverter replacement

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oxymore · #1 Post by **oxymore** » Sat Sep 29, 2007 2:11 pm

Hi,
Over the past year, since I upgraded the memory on my IBM R31 Thinkpad, I have had intermittent problems with my screen blacking out. It's not completely gone, just extremely dim, but I can make out the things on screen by using a torch. At first, I was able to trigger it back by leaving the lid open and never closing it, taking all the usbs and plugs out of the back, or re-starting it.

However, it seems like nothing I do will trigger it on now. I've done a search and apparently the commonest cause is that the inverter needs replacing. Would this seem like a sensible thing to buy?

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0157468577

Does anyone know where the cheapest place would be to buy from online/north-west uk?

The only thing I'm thinking now is, i've had this laptop for 5 years now!! I'm not sure if it's worth fixing or upgrading anymore. I mean, I love it, just cos it's lasted this long, i've upgraded the memory from 128mb to 384mb and i've bought a wireless card for it but would it be worth trying to buy and fix myself a new inverter or just buy a new laptop?

Thanks!!

Moderator edit: Shortened URL to prevent horizontal scrolling and moved from T2x conference

#2 Post by **rkawakami** » Sat Sep 29, 2007 3:15 pm

Welcome to thinkpads.com!

Before you spend some $$$ (or £££), you may want to try this:

http://forum.thinkpads.com/viewtopic.php?t=48910

A cheap neon bulb, and possibly a few minutes to take off your LCD bezel, and you can determine if the inverter or backlight is the problem. The inverter can go bad but given the age of the system and the screen getting dimmer, there is a good chance that the backlight (CCFL) in the LCD is dead. If you have also noticed a pink or red tint in the display when the system is first turned on, then that's another symptom of a bad backlight. The inverter is fairly cheap when compared to an LCD replacement. It is possible to change just the backlight (CCFL cost is similar to an inverter) but there's a fair amount of labour involved.

oxymore · #3 Post by **oxymore** » Mon Oct 01, 2007 12:58 pm

Thanks a lot for your reply. Can I get these neon bulbs from any supermarket? I live in England. Or is there any household device I can take it out from? I'll hopefully try this out, although i'm so frustrated at the moment, I'm thinking of buying a new laptop, they seem fairly cheap these days! I'm gonna see if I can fix this though hopefully. Thanks!

#4 Post by **rkawakami** » Mon Oct 01, 2007 1:26 pm

No, the little NE2 neon bulbs would typically be found in an electronics supply/hobbyist shop. It is the same bulb that you can find in some mains testers like this:

http://www.mackay.co.uk/webstore/acatalog/2948.html

You would need to extract the bulb out from the shell of the tester (and probably destroying the tester in the process) in order to get the bulb near enough to the inverter to light it up. If you are thinking about connecting the mains tester directly to the output of the inverter to measure the voltage, then I would caution you against that. I don't know if the bulb OR the inverter could handle that without causing any damage. The inverter puts out hundreds, if not a thousand, volts upon power up. Shock hazard is a possibility.

oxymore · #5 Post by **oxymore** » Mon Oct 01, 2007 4:52 pm

Ah alright, I'll have a look for a mains tester or NE2 bulb, thanks! Is it easy to take the bulb out? I'm rubbish at electronics, feminine trend perhaps.

Just another um little problem! I don't know what I was doing, but I was messing on the settings for the display/ monitor I think and where it gave the option for boot-up, it was set on system and i changed it to automatic so now, at start-up after the windows xp display, where it's still dim, it goes completely black at the log-in page and I can't make out anything beyond this point! Is there somewhere I can re-set this setting?

Thanks so much for your help!!

#6 Post by **rkawakami** » Mon Oct 01, 2007 5:17 pm

Usually those types of power testers have the neon bulb firmly embedded inside the plastic case. Which makes it very hard to remove them in one piece. Not sure what/where you change those settings you are talking about. Was that in the BIOS page (holding F1 down at power up)? Or was it something in Windows?

If you are having problems with the laptop's display, you can try connecting an external monitor and see if that works. There should be a 15-pin connector on the laptop somewhere (the back or side) which is generally blue in color. Any monitor with the matching plug (aka, VGA) can be used.

Another thought comes to mind for a "free" fix.... Your system should have a tiny switch or plunger located near where the LCD panel/lid meets the keyboard. Typically, there's a small piece of plastic on the LCD bezel which pushed down on a small area above the keys. That small area is actually a switch which controls power going to the LCD (among other things). If you can find it, push it down a couple of times with a tip of a pen of pencil (not too far!; maybe about 1 or 2 mm). Sometimes that switch gets stuck/dirty and prevents the backlight from turning on.

oxymore · #7 Post by **oxymore** » Tue Oct 02, 2007 7:47 am

Hi, thanks. I tried connecting the monitor and it was fine for the start-up where it was dim, until the login page, then it was completely black again.

The setting I changed was in Windows, after I had logged in, I think I right-clicked on the desktop, went into Display Properties > Settings > Advanced, and I think I went into either the adapter or monitor tab as I was trying to see if I could update the driver. The monitor tab didn't give an option to update though, it just said 'Use hardware default setting'

All I can remember was the setting I changed was something to do with a driver/monitor on start-up, and it was set on the option 'system' on a drop list until i changed it to 'automatic'. Really wish I hadn't done this now!

Can't seem to find anything in BIOS to change it either, any ideas? It's all very vague I know, I'm trying to find it on my current PC but I can't find it

Thanks!!!

#8 Post by **carbon_unit** » Tue Oct 02, 2007 8:14 am

oxymore wrote:Hi, thanks. I tried connecting the monitor and it was fine for the start-up where it was dim, until the login page, then it was completely black again.

Try pressing Fn-F7 at this point and see if you get the login screen. Fn-F7 switches the main display from the LCD to an external monitor to both and then back to the LCD.

oxymore · #9 Post by **oxymore** » Tue Oct 02, 2007 8:29 am

Thanks, but no luck

Still black.. is there a way in BIOS I can reset it? I tried safe mode too, but as it loads, it doesn't get past the list of drivers and then stalls there..

Btw, the point at which it stalls in safe mode is 'Mup.sys' I think!

tjb44 · #10 Post by **tjb44** » Wed Mar 23, 2011 11:02 am

Is it the backlight or the converter?
T42, black screen... can faintly see with flashlight.
Not pink. No dimming before it went out.
Every once in awhile the screen will come on full bright.
Shall I buy just converter(easy to install) to try it first or???

#11 Post by **RealBlackStuff** » Wed Mar 23, 2011 11:09 am

Unscrew the keyboard, lift it up at an angle towards the LCD, but leave it connected.
You'll see the fan on the left. To its right you may see an ATI 7500 or 9000 or 9600 chip.
Press on various corners while trying to start.
If it now comes on, you have a loose GPU, which needs reballing.
See also the links in my signature.

tjb44 · #12 Post by **tjb44** » Wed Mar 23, 2011 2:11 pm

So bill, you think it may not be the backlight or inverter but instead a loose
chip?
I made a spelling error in my post.
I meant 'inverter' not 'converter'.
I've replaced inverters and backlights before and thought
that when I could see the graphics of the desktop with a flashlight
that it would be either the inverter or backlight. I wondered if it
there was a way to tell which it was.

ajkula66 · #13 Post by **ajkula66** » Wed Mar 23, 2011 2:31 pm

tjb44 wrote:

I've replaced inverters and backlights before and thought
that when I could see the graphics of the desktop with a flashlight
that it would be either the inverter or backlight. I wondered if it
there was a way to tell which it was.

And it could very well be a blown fuse on the motherboard as well...

Inverter normally either work or it doesn't...and usually does not trigger the effect that you've been experiencing...a bad backlight does.

#14 Post by **rkawakami** » Wed Mar 23, 2011 7:54 pm

tjb44 wrote:Every once in awhile the screen will come on full bright.

That does not sound like a fuse, unless it's one of those thermal types. Could be the inverter; could be the backlight. Could also be the lid switch if you've set the OS to "do nothing" when the lid is closed. The only way to tell is to swap the part that might be the problem (inverter, backlight, motherboard, etc.) with a known good unit. Since the inverter is the easiest and cheapest to do, that would be where I would start but odds are you have a worn backlight.

tjb44 · #15 Post by **tjb44** » Wed Mar 23, 2011 8:21 pm

excellent help from you guys! Thx!
I think I'll order backlight then.
If I'm gonna open it up, might as well put the
backlight in and be done with it. Might even
order the converter as well from ebay since they
go for under $10 these days!