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15" versatile and affordable laptop. Has both AMD and Intel models.

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Lenovo Motherboard schematic/backlight fuse location

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I'm looking for a schematic for the motherboard in my Lenovo 81UT003WUS. The motherboard part number is 5B20S42804. Have a no backlight situation, pretty sure it's the fuse but can't find it to check. HELP!! :) Occurred after screen replacement, which I believe was faulty. Installed screen in 2 identical laptops to troubleshoot and both now have no backlight on any screen. The screen part number is NV156FHM-N61. Thanks for any input.

P.S. Laptop does display very dim image, also works fine on external display.

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Hi @moster1002 ,

Did you disconnect the battery from the systemboard before doing the screen replacement?

Sometimes you can find the schematic for a motherboard by searching for the motherboard's "board number" rather than the model or part number of the laptop i.e. search for "(insert motherboard board number) schematic"

The board number is printed on the motherboard itself.

Looking at the datasheet for the LCD display (is it a BOE NV156FHM-N61 screen?) I don’t think that it is only a fuse problem as there are 4 backlight power feeds from the motherboard to the screen so there may be more than one fuse. I think that it may also be a problem with the backlight enable lead.

Given that the display has now affected some 2-3 identical laptops there may be a problem with the replacement screen or perhaps it is the incorrect one for the model i.e. different pinout to what is needed to match the motherboard.

On p.14 is the pinout for the screen. pins 26-29 are the 4 backlight power feeds and pin 22 is the backlight enable lead.

The way it works is that there is always power supplied on the backlight leads to the screen and then a +3.3V signal is sent on the backlight enable lead (BL_ENABLE) to the screen to turn them on and off.

Where did you get the LCD panel model number from?

Looking at the parts list for a Lenovo S145 -15API (is this your model? found this by searching for Lenovo 81UT003WUS that you provided) there are two model variants, Type 81UT and Type 81V7. See the images below to view the Lenovo LCD part numbers (FRU) for all the various screen options.

Do any of the numbers match what is on the original screen or perhaps on the replacement especially in the Type 81UT model as there is a UT in the model number you posted?

I haven’t searched using the part number only to see what the actual screen was as I didn’t know which model variant you have.

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(click on images to enlarge for better viewing)

Hopefully this is of some help

Update (01/03/2021)

Hi @moster1002 ,

In that case it may be a faulty panel.

The number you posted is the Lenovo part number for the motherboard.

Using that number I found a board online and from it the board number i.e. GS440&GS540 NMC511 rev 1.0 2019-05-28 (See image below)

Verify that it is the same as yours

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(click on image to enlarge for better viewing)

At the moment the only schematic (I think it is anyway and not something else related to the motherboard) I could find is here in the 1st post but you have to pay for it. You may have better luck finding one for free.

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Thanks for the reply. 81UT would be my model variant. I bought the screen on Amazon as I had replaced the screen on the other machine we have back in August with no issues. Just reordered the same screen. I got the part number off the back of the screen. BOE NV156FHM-N61 that is the original panel that was in both machines. I didn't notice until after all this happened that the screen they actually sent me was N156HCE-EN1 Rev. C1 in a box that had the original part number on it. I'm assuming it was a compatible part though I don't know. Maybe that was the issue seeing how it has affected both computers. The fact that the old screens which were working fine now won't backlight is why I believe it could be a fuse issue. I have searched high and low using the motherboard model number to no avail. And no I didn't disconnect the battery before replacement …. Stupid I know but I've never had an issue before. Lesson learned, but still…. It’s very strange that this happened on both laptops. Either the screen they sent is not compatible or it has some issue that caused a short.

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This is my laptop

https://www.officedepot.com/a/products/7...

Mine is black not silver so not sure if the one you're looking at is the same.

完成的

@moster1002

Looking at the LCD panel model descriptions in the parts list for the Type 81UT that number is not listed.

The closest is a IN N156BGA-EA3 C2 HDT AG S NB but thatdoesn't mean that it has the same pinout as the one you have.

Nearly found the datasheet for the screen that they sent you i.e. an Innolux N156HCE-EN1. It is not a Rev. C1 but hopefully that only means a minor change and not a totally different model.

To view it you have to give an email address, which I didn't want to do but if you want to then download the datasheet and compare the pinout to the one that I linked above and see if they are the same.

If they're not then it was a compatibility issue. You may be able to contact the supplier and get recompense for sending the wrong one. Just a thought.

If they are the same then the screen may be faulty. this may be harder to prove to the supplier though that you didn't cause it

What is the motherboard board number?

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@jayeff the motherboard number is 5B20S42804. I downloaded the datasheet for the panel they sent and the pinouts look to be the same.

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@jayeff Yes that is the motherboard. I've searched by the number you provided and the Lenovo part number.I'llkeep looking but not having much luck.

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