T61 screen woes

[rob65789]

My 14 month old t61 screen has stopped functioning. I can see a faint image, but with no backlight at all. It is 2 months out of warranty and lenovo wants $575.00 to repair. Hardly seems like a good value, so I have decided to attempt self repair, but so far no success. I am quite frustrated and would appreciate any insight.

My t61 is a Type 7662-CTO, 2.5 T9300, 160gb 7200 HD, wxga+ 1440 x 900 Type 42T0427 LG screen. I purchased a new screen that i believe to be the exact replacement LG LP141WP1 (TL) (B8). Additionally I purchased a new inverter Type 14W4178. I was able to take apart the screen bezel and remove from hinge without incident. Close visual examination of the inverter reviled a small dark spot on the circuit board near the hard drive display lamp.

The first thing I did was change the inverter and try booting. Same problem, not light from screen. I then replaced the screen and tried booting again. Same problem, not light. I then ordered another inverted thinking maybe the replacement was somehow defective, but the second replacement does not work either. I am not positive, but when I booted after installing the second inverter card, I think I may have herd a small popping sound.

It now occurs to me that maybe there could be something else at work here. Is there something that could be causing the inverter to fail? The small function lights work fine, so it appears to be receiving power. I am at my wits end with this machine and am seriously considering smashing it into little bits. (only kidding.) But, I am generally pretty good diagnosing and repairing electronics but this one has me stumped. I would be grateful for any help that would allow me to get this laptop functioning again.

[Brad]

Welcome to the forum.

The only part left to replace unfortunately is the motherboard. There could be a possibility of LCD cable failure but in my experience it is more than likely the motherboard. Which video card is on board?

If it helps I think replacing the motherboard is easier that working with the LCD which you have already done.

Brad

[i.thinkpad]

The only part left to replace unfortunately is the motherboard. There could be a possibility of LCD cable failure but in my experience it is more than likely the motherboard.
Brad

rob65789 claimed 'I can see a faint image, but with no backlight at all.'. IMO, it is unlikely to be the motherboard. To further confirm this, you may connect an external monitor with the VGA output.

I heard someone here who replaced failed backlight to save a dim LCD. You may search the forum and consult them. Good luck.

[rob65789]

Thank you for the info. I does not seem like it is the motherboard, as the laptop does function fine with an external monitor. The video is the nivda 140.

I do have two more bits of information. When I connect an external monitor, neither windows display settings or nvida control panel can detect the built in display. The only choice is the external monitor. Yet, when I power up without an external monitor connected, I can see the thinkpad splash screen in the non backlet background and the laptop does boot. Another detail is the function lights on the inverter card have stopped working except for the wireless indicator on the far left.

I did search these forums and saw something about an internal fuse, but honestly could not find much information. maybe this is what you were saying about being the motherboard? I am about to check the hardware installation manual regarding fuses, but am getting more discourage.

One more thought. I did have a problem with this machine overheating and sudden shutdowns several months back. I opened a service ticket back when the warranty was still in effect, but did not follow up because I discovered that thinkpad fan control worked effectively If I turned it on when i noticed the machine getting hot. Anyone know if overheating could cause this type of screen problem.

Thanks again for the help.

[ajkula66]

The fact that the machine displays on external monitor means next to nothing. There are two separate outputs, digital for the LCD and analog for the VGA. One can work while the other is completely shot, I've seen it many a times on a variety of ThinkPads including couple of them with symptoms being exactly the ones OP describes.

Given that we're talking about a machine with nVidia GPU, I'd be placing my bet on Brad's diagnosis.

Good luck.

[dr_st]

But the fact that there is an image on the LCD matrix, just no backlight, leads me to believe that it is NOT a GPU/mobo malfunction.

[Brad]

I would normally agree. On T61's though I have seen this before and so far motherboard replacement fixed the problem.

Brad

[dr_st]

Interesting. Perhaps it's not a problem with the GPU then, but with some power circuitry that channels power from the DC jack to the inverter. This would also explain why there is no problem with the VGA output.

[richk]

There is a fuse that can blow on the MB, but there is always some other failure thast caues the blown fuse. It can happen if you break the screen "the wrong way" or mount the wrong screen, but in your case, it sounds like the MB power circuitry

[rob65789]

Thanks for all the help guys. I am now considering that motherboard may indeed be the problem. One additional piece of information that I am not sure matters, but when in the dock, the laptop will run both a vga and dvi monitor very nicely. Its just that the option to use the built in display is gone, so I can not even direct the video card to that display.

I doubt I will try the motherboard repair, unless there is a way to purchase one inexpensively. So far, I and seeing in excess of $300. I am figuring that the laptop is worth maybe $300 broken and $600- $700 working, so why put over $300 into something that might not even work, not to mention the time and energy. I also have the mini dock, ultrabay battery, extra 7 cell, extra power adaptor and a hard drive caddy that I guess would add some value.

I must say though this thinkpad has turned out to be a pretty bad experience. This was my 6th laptop in ~15 years, (4 apples and 1 dell), and has proven to be the least reliable. I moved to a thinkpad because I herd so much about quality and value. I guess bad things can happen to good products, but sheeze, never though this. I have always been able to service my laptops with a minimum of struggle. In fact, 3 of them still work fine. I think I am going to do some new laptop shopping later today, I really do not want to spend another week working on my 9 year vintage Pismo.

Bay far and away the best thing about thinkpads has been this forum where I have been able to receive quick quality insight into the issue. I do sincerely thank all of you for that.

[agarza]

Rob, a shame what happened to your Thinkpad.
You probably are better off selling your broken Thinkpad along with the LCD assembly and inverters you bought here at the Marketplace, I'm sure somebody would be interested in acquiring those.

[rutteger]

Any luck with this issue? Or did you cut your losses? Having similar issues with a R61 (which of course if very similar to a T61) even down to the non functioning LEDs on the inverter board > http://www.thinkpads.com/forum/viewtopi ... =5&t=80159

[dzuo]

The screen will not be damage, also your motherboard...

The only cause of the failure is due the light tube aging inside the screen (on the botom of the scrren), another probable is on the inverter for this failure, but as your described, I belive the inverter is ok.


Please note 'do not touch the light tube while you make the testing after you installed the new one , the voltage between the light tube is so high ( danger: over 10,000 volt).

The replacement cost is around 5 dollars only (in my location), no need to replce the screen complete.

Attached the LIGHT TUBE replacemment guide for your reference.

http://blog.163.com/06-11-18/blog/stati ... 102232112/


Hope it can help you resolve the problem.