T21 LCD

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fleamourian · #1 Post by **fleamourian** » Sun Oct 28, 2007 6:16 am

Hi

I need some pointers in the right direction.

The screen powers up but you can only see an image under scrutiny. There appears to be no back lighting at all. Is this an inverter problem? In which case what are my options? It has just suddenly happened this morning & I am having to use an external monitor to write this. The inverter card looks fairly simple to replace having recently replaced the keyboard bezel because of a corner crack.

Is my diagnosis correct? Please advise.

losmeme · #2 Post by **losmeme** » Sun Oct 28, 2007 7:14 am

It is a backlighting problem, replace the backlight, or replace the entire LCD screen.

joester · #3 Post by **joester** » Sun Oct 28, 2007 8:33 am

I would start with carefully checking the cables and connections.

Next would be the inverter board, followed by contacting jamiphar about bulb replacement.
for what he charges, this would be my preferred choice unless the screen has scratches or pixel issues.

Joe

Msmax · #4 Post by **Msmax** » Sun Oct 28, 2007 11:20 am

If the backlight does not come up then you can have:
- mainboard failure
- LCD cable failure
- inverter board failure
- defect backlight tube

Hav erepaired several of T2x machines already, most of them had LCD cable failures. Replacing the cable fixed this problem in many cases. In one case I had to replace the inverter board.

Msmax

#5 Post by **rkawakami** » Sun Oct 28, 2007 12:18 pm

See this:

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

for a non-invasive way to check if the inverter board is firing up and delivering any high voltage. If the neon bulb flickers on for a brief time but you do not see the backlight turn on, then the backlight is probably dead. Note that you must get the neon bulb as close as possible to the inverter board's output connector or coil. If the neon lamp does not turn on, then the problem is in the inverter, the LCD cable, the connections of the cable to the motherboard and/or inverter, or the motherboard itself.

Website · #6 Post by **tfflivemb2** » Sun Oct 28, 2007 12:40 pm

losmeme wrote:It is a backlighting problem, replace the backlight, or replace the entire LCD screen.

I'm not so sure.

Was this a sudden outage? Did you have a bright screen before hand, or did you have a pinkish/reddish tint in the LCD?

If the screen had been nice a bright before hand, then I would try replacing the inverter first. Normally, they either work or they don't. If it was sudden then the odds are in your favor that it is the inverter, unless the laptop had been dropped, which could have killed the backlight.

doylnea · #7 Post by **doylnea** » Mon Oct 29, 2007 8:34 am

I'm considering swapping the LCD from a SXGA T21 I just purchased with an XGA from a T41, as the recipient of the T21 will only ever use the XGA setting of the SXGA LCD.

However, I read a comment somewhere that the T21's can only use T21 LCDs, whereas some of the later T-Series can use an LCD from other models? Is that the case, or did I misread a post?

fleamourian · #8 Post by **fleamourian** » Tue Oct 30, 2007 7:45 am

This was a sudden outage. No pinkish/redish tinge & I've never dropped my laptop. I've ordered an inverter from eBay for £12, should arrive soon.

fleamourian · #9 Post by **fleamourian** » Tue Oct 30, 2007 11:20 pm

Well stayed up till four in the morning, outa work=no routine, taking apart me laptop. It is now in pieces awaiting the new inverter, here's hoping!!!

I guess I'll re-assemble the bare minimum to test it, jst in case.

fleamourian · #10 Post by **fleamourian** » Thu Nov 01, 2007 10:44 am

Well got new inverter thru post from Finland of all places!!! No dice, will now test both inverters with neon LED (I shoulda done this in first place.)

Meanwhile here is a pic of a mystery bracket thingy which for the life of me I can't figure out where it goes?!?

http://i218.photobucket.com/albums/cc93 ... CN0838.jpg

Anyone out there recognize it!?! Where does it go & what does it do? I assume it's non-essential.

Oh, & the next thing I'll be trying is the LCD cable. Can someone confirm that the screen on a T21 type 2647 8BG is XGA before I buy. The screen itself is a good one with no dead pixels or scratches only a few minute hot spots. So if it comes to it I'm thinking it may be best to get scrn repaired by, hopefully, Jamiphar.

Moderator edit: 125KB image is a little too big (try to stay around 50KB). And without a *PIC* note in the subject line. Changed to link.

Msmax · #11 Post by **Msmax** » Thu Nov 01, 2007 1:20 pm

That goes under the screw which will fasten the LCD cable to the systemboard.

Msmax

fleamourian · #12 Post by **fleamourian** » Tue Nov 06, 2007 12:24 pm

Thanks Msmax!

On closer examination of the black wire from the bottom right hand corner of LCD to the inverter. There was a flash of silver where the wire had been worn through under stress. This was directly where rib of outer LCD lid housing came in contact with the wire. all it took was some 12p insulation tape to wrap around the black wiring & voilà!!! The screen fired up a beauty!

So joester was right in saying check all the connections first.

PS. What do u guyz use to re-stick the black plastic circles that cover the LCD screws?

joester · #13 Post by **joester** » Tue Nov 06, 2007 12:33 pm

fleamourian wrote: So joester was right in saying check all the connections first.

Follow me on this one -
Start out with the cheapest possible fix. Always.

Little sticky pads - I use NON-FOAM double sticky tape and carefully trim to fit.

Joe

vanaya · #14 Post by **vanaya** » Tue Nov 06, 2007 2:37 pm

Sticky circles - 3M adhesive spray. My dad uses it for commercial printing supplies, costly but works great.

fleamourian · #15 Post by **fleamourian** » Wed Nov 07, 2007 12:55 pm

I spoke too soon!!!

She's down again! she worked for a whole afternoon & evening then went to switch on this morning & no back light again!

Could this point towards a loose connection somewhere???

joester · #16 Post by **joester** » Tue Nov 13, 2007 12:18 pm

I would go back to the black wire and start there. Meter the wire while bending it, verify that there is no loss of continuity. check all adjacent wires in that area for mid-wire breaks.
Examine solder joints. If the screen comes back to life, run it for a while with the cover off, shut it down, and immediately feel the components on the inverter board. Warm is OK, HOT is not.

I have a feeling it's not component related. More like a wire issue or bad solder joint.

Joe

#17 Post by **rkawakami** » Tue Nov 13, 2007 2:23 pm

fleamourian wrote:Could this point towards a loose connection somewhere???

When the screen's backlight is off again, try pushing down (carefully) on the lid switch in front of the right side hinge.

Stargate199 · #18 Post by **Stargate199** » Tue Nov 13, 2007 9:43 pm

It looks like the cable leading to the bulb from the inverter is the culprit. Still if no success, try replacing the LCD cable harness. It seems like most of my T21 backlight problems was due to a bad LCD cable.

fleamourian · #19 Post by **fleamourian** » Wed Nov 14, 2007 6:33 am

I have carefully tried your suggestions. I have no multi meter as of yet however there is no power present in either inverter with neon test. Swapping LCD cables produced nothing. It has not jumped back into life again.

I want to check the solder joints of the pink & black wire connection to bottom right of LCD scrn, to get a good view I need to unscrew metal casing. Anyone know what size screwdriver that is to avoid buying whole set?

fleamourian · #20 Post by **fleamourian** » Wed Nov 21, 2007 6:11 am

Woo-hoo!!!

Well swapped out the mobo for a IBM factory refurbished one & now she works a goodun.

T21 LCD

T21 LCD

Success!!!

Re: Success!!!

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