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KevinNZ
Posts: 7
Registered: ‎11-27-2008
Location: Auckland, New Zealand
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X61 Backlight problem

My favour that has become a nightmare! Customers daughter has (had) an X61 about 6 months old. She managed to stand on the laptop (something on the top shelf I suppose). Anyway it was immediately evident that the LCD panel was broken and I offered to replace it for her (after my recommendation to replace rather than repair was declined) along with a warning that there may be more items than just the LCD that end up needing to be replaced, and would probably anul the warranty.

1. LCD panel was purchased and installed and working fine, unfortunately a few of the indicator lights on the inverter were not.

2. I ordered a new LCD cable and inverter to be sure that the second procedure would cure the lights and any other issues. At this point the backlight suddenly stopped working. I guessed that this was probably the inverter since I already had issues with some indicator lights.

3.The new parts arrive and are installed, indicator lights are now all OK but the backlight is still dead.
- No power coming from the inverter so unlikely that there is a problem with the (new) LCD panel
- Reset BIOS incase it had become confused during the surgery
- Lid close switch is working correctly
- plugs/connections all checked

- tested to make sure that was not set to external monitor (Fn F7) 

4. Logic leads me to painfully conclude that the problem must lie on the mainboard. (Computer repair rule 1 - the most likely problem will always be the worst possible). The cost of a mainboard is going to push the parts cost to more than the cost of a new laptop so I am really, really hoping that some most kind benevolent person can prove me wrong. I am still at a loss as to why the backlight stopped working. I subsequently tried reinstalling the original inverter and all indicator lights are OK which says to me that the LCD cable was actually the culprit. Could the original inverter have developed a fault that buckled the motherboard?

Any light (pun not intentional) on the subject would be most welcome. Despite my recommendations and warnings I will still look a right idiot and could potentially loose my best customer through this. Any recomendations on swift and painless suicide may also be welcome!

Perhaps the question is whether anyone has had board level experience with the backlight circuitry on the mainboard?

ajkula66
Posts: 7,351
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Registered: ‎11-23-2007
Location: USA
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Re: X61 Backlight problem

Welcome to the forum!

 

I'm going to say that you have an excellent train of thoughts, although I doubt that this statement is helping you a lot right now.

 

Here's the thing: yes, the original inverter could've damaged the planar. Now, what happens if you connect the machine to an external LCD? If it doesn't display, case closed, you have a motherboard problem. If it does...you have a 50% chance that the new inverter is defective.

 

I'm pretty interested in your findings for my own selfish reasons...if it turns out to be the planar, I'd be looking for a blown fuse first.

 

The best of luck and keep us posted.

Cheers,

George




In daily use: T43pSF, R60F, T410, W510

Backups: T60, T61p, R500F

For sale: T60 (15" SXGA+ IPS), T61p (14" SXGA+ & 15.4" WUXGA),

Rebuilding: A31p, T42p, X24

Non-ThinkPads: Panasonic CF-31 & CF-52, HP 8760W

I build FrankenPads....scary FrankenPads...

S = SATA-mod (on T43/p units only)
F = FrankenPad
L = LED-mod utilizing an UXGA AFFS LED screen


Please DO NOT PM me with requests for individual support, but post your questions and concerns in the appropriate section of the forum where other users can benefit from them as well. Thank you.
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KevinNZ
Posts: 7
Registered: ‎11-27-2008
Location: Auckland, New Zealand
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Re: X61 Backlight problem

Hi George. Hearty thanks for the interest. The display side of the laptop is working as expected. External monitor works and it is also evident under appropriate light that the laptop display is working - its just the backlight that is faulty. (big word that "just").

 

I have confirmed that I am not getting any power from the output of the inverter (at the output plug). I have also just had a quick look at the original inverter and noted that a resistance measurement accross the pins of the transformer yields values ranging from very high to nothing at all. Also, there is a three leg SMD device that looks like it may be performing the switching for the primary that I would love to test. I need to see if I can lift a code and identify the rascal. I think I may well haul out the oscilloscope and do a bit more work on the inverter. I guess the hypothesis is that the original inverter was faulty and either it has damaged something further back; or the new inverter is also defective (which seems a bit of a long shot). I wonder what sort of signals emanate from the motherboard? Possibly various frequencies that fire the previously mentioned device depending on the required voltage? Thinking aloud here, but maybe I should be looking for waveforms around the primary circuitry.

I will let you know how I get on. The fuse that you mention sounds like it may well be my final destination. I hope you dont mind if I pick your brains as to the location of the device. I am a reasonable dabler at board level repairs but I imagine it will take some time and a bit of thrashing about to locate. Forums are wonderful; how did we manage without them?

 

Many thanks again for the advice.

 

Regards

 

Kevin

ajkula66
Posts: 7,351
Kudos: 695
Solutions: 732
Registered: ‎11-23-2007
Location: USA
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Re: X61 Backlight problem

I've never seen a X61T open for surgery, so I really can't help you there, but...

 

You may want to take a couple of pictures once you open it up, and post the links both here and on http://forum.thinkpads.com

 

I've given up on repairs of this nature years ago due to health reasons, but can still think in a straight line...or at least believe so...:smileywink:

 

Anyway, if I were to play with that ThinkPad, I'd compare resistances and such between the old inverter and the new one...just in case. I'd also try to find out more-if at all possible-about the initial "stepping on" accident.

 

That's about all I have for now, except for keeping my fingers crossed, please keep us posted.

Cheers,

George




In daily use: T43pSF, R60F, T410, W510

Backups: T60, T61p, R500F

For sale: T60 (15" SXGA+ IPS), T61p (14" SXGA+ & 15.4" WUXGA),

Rebuilding: A31p, T42p, X24

Non-ThinkPads: Panasonic CF-31 & CF-52, HP 8760W

I build FrankenPads....scary FrankenPads...

S = SATA-mod (on T43/p units only)
F = FrankenPad
L = LED-mod utilizing an UXGA AFFS LED screen


Please DO NOT PM me with requests for individual support, but post your questions and concerns in the appropriate section of the forum where other users can benefit from them as well. Thank you.
.
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KevinNZ
Posts: 7
Registered: ‎11-27-2008
Location: Auckland, New Zealand
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Re: X61 Backlight problem

An update. Finally managed to get around to chasing up on a potential fuse problem. Opened the beast up and located a bad tooth within a few minutes. The track from the fuse leads to the LCD cable connector so I am mildly confident that the problem may be solved.

 

Next challenge is to identify the suspect. In scratching around it seems as though Little Fuse (brand) are used on the Lenovo boards. Their website though has a myriad of fuses and it is going to take me some time to identify it using their website. It is labelled P if that rings bells with anybody. I have images that I will post if I can find a resident url for them somewhere. 

 

I am not too concerned with identification as I intend outsourcing the replacement job to one of the many electronics manafacturers around here. I have neither the tools nor facilities (certainly also a bit thin on the faculties) to go down to this size job. They will no doubt be well equiped to ID the fuse quite easily.

 

 

 

 

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KevinNZ
Posts: 7
Registered: ‎11-27-2008
Location: Auckland, New Zealand
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Re: X61 Backlight problem

I think I managd to identify the fuse. Looks like it is going to be a 3amp from this series of fuses.

 

http://www.littlefuse.com/data/en/Data_Sheets/467.pdf

 

Now to find someone who stocks these or an equivalent somewhere nearby.

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KevinNZ
Posts: 7
Registered: ‎11-27-2008
Location: Auckland, New Zealand
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Re: X61 Backlight problem

Problem solved. If anyone lands up with the same problem, it is fuse F2 that needs to be replaced. It is to the left of the LCD cable on the motherboard. I have images if you need a visual - just email me.
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Justintoxicated
Posts: 9
Registered: ‎04-22-2008
Location: California
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Re: X61 Backlight problem

Can you provide me the details on how to diagnose this issue?

 

I recently just bought a new LCD for my laptop (X61S w/ ultralight).  last time I checked the broken  LCD light up (but was messed up).  This was months ago and the laptop has mostly just been sitting ever since, I did use it once or twice once I had removed the old screen.  

 

I went to put the new screen in and it seems to turn on but does not light up, neither does the old screen so it is unlikely it is a bad CCFL. I want to determin if the inverter is bad, or if the problem exists before the inverter.  (no power at the plug where the screen plugs into the inverter, but the inverters LED's DO light up).

 

I located F2 but could not detect any current flowing across it.

 

Not sure where to go from here so any help is appreciated.  I have turned on email notifications.

 

Thanks,

Justin.

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KevinNZ
Posts: 7
Registered: ‎11-27-2008
Location: Auckland, New Zealand
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Re: X61 Backlight problem

Hi Justin,

It was a while back, but will try and get the old head into memory recall mode. There are a bunch of things that can go wrong. Probably not the inverter - the lights that you see have nothing to do with the inverter circuitry - they relate status of hard drives, power etc, and are fed by different circuitry. It is far more likely that the inverter is not being supplied with power from the main unit. Be careful checking the output of the inverter - it is probably around 600V when healthy - and also very vulnerable. If you must check the inverter, rather tackle the supply side (heavier circuitry to the left)

 

Some basics (forgive me if this sounds really obvious). Make sure that your graphics are being directed to the LCD screen and not the external connector (changed with the Fn button and key(s) along the top of the keyboard if I remember correctly). Do you get graphics if you connect an external monitor? If you do not have an external monitor available, you should be able to make out that there is some output to the LCD panel if you look carefully in the right light. If you are not getting any graphics output, than your problem may have nothing to do with the LCD panel at all. If this is the case I would probably start by taking to the board (switched off) with a multimemter and testing continuity of the fuses in that part of the board (there are quite a few if you look carefully).

 

If you are not getting any voltage on either leg of the fuse, and the above is not true, then the problem must lie further back in the circuitry - and "rest of the fuses check" applies. When you say you are trying to measure voltage on the fuse...check that you are using a valid reference for the negative (assuming that the voltage on the fuse is +ve). The backlight may have its own independant power supply. Best way to check the fuse is a continuity test (Ohms - should be zero or very close to it) accross the fuse with power switched off.

 

If we assume that the fuse and graphics engine is OK and there is in fact not a problem with the main board; the other strong possibility is that the connector cable between the unit and the panel is faulty (the plastic strip thingy with tracks). I have cured problems twice in the past by replacing these and in neither case was it at all obvious that the connector was a goner. Gut feel is that this is the most likely reason given that you said it was working. They do not seem to take kindly to being worked on.

 

Good luck and let us know how you get on. I am in New Zealand by the way, so replies may not be immediate!

 

Cheers

Kevin

 

 

 

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Justintoxicated
Posts: 9
Registered: ‎04-22-2008
Location: California
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Re: X61 Backlight problem

Kevin, thanks for the reply.  There is indeed a signal going to the screen as I can see the windows and bios screens, but they are not illuminated by the backlight, so they are  pretty unusable.

 

I'm not sure what the fuses look like, I didn't see anything that looks like a typical fuse.  Are these fuses soldered to the mainboard?  I did identify something that said F2 next to the ribon cable but it looked more like an SMT capacitor.  I'm Not an electrical engineer, I know only some of the basics.  Also if there is no voltage coming out of the inverter where exactly should I try to get a reading from next? is there a place I can test without taking apart the base of the laptop?  The inverter is pretty sealed up in some kinda plastic thing so I don't think I can easily get to components on it.

 

I'm not sure how to unplug the ribon cable from the mainboard or from the power inverter.  It was easy to unplug the LCD but I was afraid to mess with the rest of it. I'm thinking to buy a new ribbon and power inverter, since if neither of these fix the problem it would not be worth replacing both the main board $320, and LCD $215 since I can just get a new laptop for that much.

 

The one LCD is indeed bad, but it used to at least light up, the other LCD is brand new (Finally found an ultralight panel for $215 instead of $430)  Lenovo charges way to much for a 12.1" LCD....

 

I put it all back together last night so as to avoid losing parts.  Spent hours working on this, and now a couple hundred dollars as well.  It sounds like my best bet would be to find out if the ribbon cable is bad or the inverter.  I need to get on the ball though because I only have a few days where I can still return the new LCD (it's worthless to me if the Mainboard is bad).

 

 

The old LCD is bad because I spilled a drink on it, it still worked but looked terrible on the portion that got liquid in it.