Thinkpads Forum

ok, i probably should have asked this before i unscrewed my whole laptop, i think it will be very hard to put back together from here

i have the backlight problem where very feint visuals can be seen on the LCD. I would like to try and solder over the busted fuses, but i need to find them first.

Where abouts on the motherboard can they be found.

any help very very much appreciated.

I'm having the same problem and need to replace the fuse which I blew when replacing the LCD screen. There is another post describing the location of the fuse for a T400s:

http://forum.thinkpads.com/viewtopic.php?f=45&t=100169

They also list some properties of the fuse, but I don't know if that also applies to the T410 series. I am actually having a T410s, don't know if that makes a difference. Anyone already done that kind of repair who can give some hints?

How do you know it is the motherboard causing the problem and not the screen itself, or the inverter card?

Sorry, but I do not know what fuse it is on the MB

There is no inverter. An inverter is a device (transformer) to convert the DC used on the motherboard into the AC used by a CCFL backlight. T410 machines all have LED backlights, so it is a direct draw from the motherboard. The fuse numbers used to be standardized but since T410, they are not. There are generally 2 fuses involved and both are physically near the LCD connector. (used to be F8 and F7) They may be under black plastic protective sheets. The larger 2-amp fuse does the backlight and the smaller .5-amp one is involved with the LED icons on the screen bezel. I remove the board entirely and check with a meter. You need good equipment to replace fuses on the board. It is a multi-layer board and uses lead-free solder that melts at a very high temperature. At minimum, you need a quartz preheater and a good, temperature-controlled hot-air or infrared rework station.

Thanks for the clarification on that!

The part I was thinking to be the inverter is actually called "LED sub card" (FRU 63Y2121). So what does that part do then?

Sorry and trying not to derail off from the OP question......

Hi,

do that fuse have some part number ?
Or shall i just direct connect without fuse ?

i have a T410s with same problem, i havent located the fuse yet but it sounds like its the same problem.

thanks

The led sub card has the status led's and has the switch that senses when the lid is closed on some models.

The fuses are made by littelfuse. On most models, there is a 2 amp fuse and a .5 amp fuse. I think that the layout and fuse sizes are different on the T410s

Hello,

has anyone located the backlight fuse on the T410 model? I have one with a gone backlight. The screen itself is working but it's quite dark though. I don't have any HDD and operating system in atm, so it won't be a power managment issue.

Google is your friend, look for "Lenovo T410 Nozomi"

I'm not good with circuit schematics, but am I right that the F3 is the LCD backlight fuse? The fuse seems to be ok when I measured it... Hmm, so what could be the problem? Lid switch?

Edit. Added a pic of the suspected fuse.

http://oi58.tinypic.com/ogm8pj.jpg

Moderator Edit:
Warning: schematics are Confidential Property of the manufacturer and can NOT be allowed here!
Also, your pictures are WAY too big! Converted to a link.
Please read the Forum Rules:
5. IF you must add a photograph to your post, PLEASE limit the size to 50k or less and place a warning in the subject line.

Did you also check F19 to the left of it?

Yes I did. It was ok.

Faulty LED-board or even faulty screen?