T20 issues + upgrades (LCD Fault) *PICS*

[lilserenity]

Hello,

I'm fixing up my brother's rather battered T20, it's really quite a rough looking machine now but everything still works except a fault with the screen. You can still just about make out the display but the backlight is not working. He had to jiggle it about and push the back of the lid where the inverter is.

I have taken it all apart, reseated everything and no change to the display. He did note that the display may have had a slight pinkish hue before it went which could mean it is the backlight.

Does this sound indicative of that or the inverter? I plan to replace the latter this week as it's cheap to test, but the symptoms sound more like the backlight, does this sound likely?

I'm thinking that it might be easier to buy something like a faulty (motherboard wise) T22 which has a much better condition casing and place the T20's motherboard into it, and make use of the faster T22 CPU (likely to be a 900MHz PIII Mobile as they are common).

Would this work, I think they are pretty much straight swaps.

Also if I don't go that route (say it is the inverter or a duff T22 isn't around at a good price) what is the fastest PIII Mobile a T20 motherboard can take, I seem to recall there being some T20s that have issues with using a 1GHz PIII Mobile? I would look for a 256KB L2/100MHz CuMine based part, not a Tualatin one.

If anyone does have a duff T22, or even a T20/21, and is in the UK which has a good LCD, I'd be interested to hear from you as it seems to make more sense to go that route than pay £30 for a LCD, when I can pick up a duff T2x (not T23) for the same kind of money.

Thanks,

Vicky

[Stargate199]

Let me ask you this, when you do get the LCD backlight to come on, does it have a pink/reddish hue to it? If so, it would be best to replace the LCD. If it doesn't, try removing the bezel and see if the LCD backlight cable is being pinched. If there is no red hue, and the cable is not pinched, the I would simply replace the inverter. I have a T21 that has this problem, but it seems to be working for the time being.

[SMA]

Hi

To me it sounds like you have a bad lcd cable.
I doubt that it is possible to move the inverter by pushing the back of the lid, as the inverter is located below the lcd panel.
What I think has been moved by jiggling and pushing at the back of the lid has most likely been the lcd cable.
They have a bad happit of breaking. I just had two such, one in a T20, the other in a T21.

It is possible to measure whether you have a good or a bad lcd cable.
Use a multi meter and measure between pin 56 on the connecter that fits the motherboard and pin 9 on the connector that fits with the inverter. If these two pins are not connected, then the cable is defect.

I belive this is the cable wire that will break most often, at least it was in 2 of mine.

After having measured a known good cable to verify that these 2 pins are supposed to be connected, I made a temporary fix, by connecting these 2 pins with a new piece of wire, and managed to get the backlight going on both machines.

Naturally, you should not try this fix unless you are sure what you are doing.

[tfflivemb2]

If your brother is pretty sure that it had a pinkish hue, then I would say that it is the backlight. Replacing the inverter is an easy step.

I think that you are already going in the right direction. Finding a dead T22 should be relatively easy and cheap (less than $75-100)

[lilserenity]

Thanks for all of your responses so far. Very helpful indeed.

I did not see the laptop when it started playing up, I am just aware that where my brother demonstrated pushing the lid was indeed where the inverter sits.

There is no backlight working at all at the moment, you can very faintly make out the screen, windows etc., but it's far to dark as the backlight is dead/not powered.

As noted I did dismantle the entire system piece by piece (and there were a lot as many of the plastics are cracked, he really must treat it rough!!!) and reseated all of the cables including the LCD cable.

This made no improvement (thankfully didn't make anything worse lol!), so I have received the inverter this morning. It was £5, or about $10 USD at current exchange rates so it wasn't an expensive thing to try at least.

I'll try fitting it at the weekend. Unfortunately I don't have a multimeter to test the voltages but I am thinking more along the lines of resolving the issue by buying a dead but good condition T22 which I can retrofit the T20's motherboard into, with a working full LCD screen assembly, and combine the RAM, pop in the T20's hard disk and re-use the PIII 800/900 on the T20 motherboard and bin the rest. (Really, apart from the CPU, there is nothing worth saving on this really battered T20!!)

Give it some due though, he's had it seven years and apart from the LCD it hasn't missed a trick.

I'll let you know of progress,

Thanks

Vicky

[lilserenity]

Ok, it's not going great but not too awful either.

I got a replacement inverter. That did not work.

So I tried one LCD screen which I bought as working, that replicated the issue of not being backlit and it had a huge great white dead stripe down the middle of it. As such I have been refunded for that one, thankfully.

I have a second s/hand supposedly working screen on the way for £10, and also a cable for £7.50; and I am hoping the combination of new cable, inverter and screen should cover all bases!

If not, I have no idea what is going wrong with it.

If this all works, I can safely pop in a nice 60gb 5400RPM hard disk for him, and all he will need then is another 256MB module, maybe a PIII 850MHz CPU which I can get easily enough which will just eke out a little more from it.

It does sound to me though that this was an issue of a dodgy LCD cable, only time will tell though.

Vicky

[Msmax]

I think it is your cable.
I have repaired several of the T2x series with same problem as yours. Check the cable as SMA described.

In one occasion I had a bad inverter. One pin of the coil had a bad solder joint on the inverter PCB. After fixing that the inverter worked fine.

Msmax

[Robbyrobot]

Use a multi meter and measure between pin 56 on the connecter that fits the motherboard and pin 9 on the connector that fits with the inverter.

Where can you find the pinout diagrams for the connectors? I have a T21 with similar problems and would like to check the cable.

[lilserenity]

Unfortunately the postie came after I left for work so I haven't been able to try fix it today. One bonus is that the seller who sent me one screen and refunded me when it turned out to be dead (huge white stripe on the display), I ordered a second only to find he sent me two!! So if the original screen is OK on the T20, that means my brother will have two spare screens, pretty darn handy!

I have managed to replace all the screws on the t20 and managed to clean it up nicely with some Jif/cream cleaner. Looks a lot better for it. I'll leave it to defrag the slow 4200rpm 30GB hard disk tonight, though I do plan to install a 60GB 5400RPM drive into it, and then he can source another 256MB for it.

I'll let you know what happens!

Vicky

[Stargate199]

My old T21 had this problem too and I thought it was related to the inverter. After performing some tests, it turned out that is was the entire Display cable that connects to the motherboard. This is fairly simple to replace if you know how to disassemble your Thinkpad. Refer to the Hardware Maintainence Manual if you are unsure how to take apart your thinkpad. You can download it from Lenovo's website.

[SMA]

Where can you find the pinout diagrams for the connectors? I have a T21 with similar problems and would like to check the cable.

I do not have a pinout diagram for the connectors, and I have no idea of where it could possibly be found.

Would also like to note, that to be able to measure whether an lcd cable is good or bad, as I have suggested earlier, one must know how to use a multimeter and how to locate the correct pins.

[lilserenity]

Yep, it was the LCD cable. Funny as to look at it, it looks as just as good condition as the one that is broken, must be a fracture underneath the sheath.

All I need to do now is araldite a couple of fractures in the palmrest (typical right hand by Ultrabay spot and oddly behind the keyboard near the hinge cover) and the machine is ready to go back for another few years of beating by my brother

I'm going to pop a 60GB 5400RPM drive into it to replace the aging 30GB 4200RPM in it when my replacement 160GB drive arrives (The 60GB is presently in my T40), which will help. After that, if my brother wants to pop something like an 850MHz/900MHz PIII Mobile in there, and an extra 256MB RAM that's up to him. Considering that would be about a £30 upgrade, it might be worth it as I think the machine has a lot of life in it yet as I'm not convinced that he needs something like a T40 series to do the work he does; and even then he would need to find about £200 for a T40. As such I still think the T20 is an economical option for the next couple of years, and probably would stand up to the harsh beating he gives it better than a T40

Thanks!

Vicky

[Robbyrobot]

I do not have a pinout diagram for the connectors, and I have no idea of where it could possibly be found.

Would also like to note, that to be able to measure whether an lcd cable is good or bad, as I have suggested earlier, one must know how to use a multimeter and how to locate the correct pins.

Using a multimeter is no problem. Locating the correct pins is, and since you previously remarked:

Use a multi meter and measure between pin 56 on the connecter that fits the motherboard and pin 9 on the connector that fits with the inverter.

I assumed you must have some basis for the pin numbering. That was the reason for my question.

[Robbyrobot]

@SMA:

It is possible to measure whether you have a good or a bad lcd cable. Use a multi meter and measure between pin 56 on the connecter that fits the motherboard and pin 9 on the connector that fits with the inverter. If these two pins are not connected, then the cable is defect.

As unhelpful and downright impolite you were when I asked for details, I still owe you thanks for the above comment, since I just checked out a defective (no backlight) LCD cable from a T21 of mine, found the pertinent pins (which I worked out for myself) disconnected, bridged them with 0.2mm enameled wire - and now find that the backlight is functional again.

So that others won't have the problems I did determining exactly what you were talking about, I've made pictures of the mainboard and inverter plugs with the pertinent pins indicated with red arrows.

Here's the mainboard plug:


And here's the inverter plug:


For those who, like me, had problems using a multimeter on such small pins, I might note that I removed the original probes and replaced them with sewing needles soldered to the pertinent wires. That let me put the multimeter probes exactly where I wanted them.

I taped the cable to white paper to work on it. That held it flat and immobile while I did the work under a magnifying lamp. To solder the wire bridge, I tinned a short piece at the ends of a length of 0.2mm enameled wire, removed all but around 1mm, then taped the ends to the proper points on the two plugs. Then I applied a hot iron with just a trace of solder on it (0.8 mm tip) to the pertinent pins.

Now that I see that this fix worked, I'll pin the bridge with droplets of epoxy and use the cable at least temporarily.

Edit: The result looks better than I expected, and works perfectly.


Could the OP or a moderator please change the subject to warn about the images? I can't do that myself.