No Power to Display

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Lenovo Thinkpad T450

Released in 2015, the Thinkpad T450 is a lightweight, sturdy 14" business notebook that ships with a 5th generation Intel processor. The device was published in 2015

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jsnelson @jsnelson

Rep: 1

Postado: 10 de fev de 2023

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No Power to Display

The computer powers on and I can hear the (very loud) chime when Windows is done loading but there’s no video on the built in display even after replacing the LCD assembly (it appeared to include the backlight board with the panel). It is usually used with an external monitor as the previous panel wasn’t working either. PC laptops are a little outside my knowledge, but I am very well-versed in Apple repairs. In Apple terms I want to reset the SMC (system management controller) but I don’t know how to do that on a Thinkpad. Does anyone know or have additional ideas? (I have tried the Microsoft troubleshooting steps for no video and they did not resolve the issue.)

Thanks!

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jayeff @jayeff Rep: 449,1 mil 11 366 1,4 mil · Answer 1 · 2023-02-10T20:32:56-07:00

Hi @jsnelson.

Did you have the battery disconnected from the motherboard just prior to removing/replacing the LCD panel?

When the laptop is on, try shining a flashlight at an angle close to the screen and check if you can detect any images. They will be very faint if they are there, so trying in a darkened room may help to see them.

If there are no images to be seen and you've replaced the LCD panel and since an external monitor works OK it may be a problem with the LCD cable (loose connection?)

If there are images then it is a backlight problem.

The backlight voltage supply is always supplied to the display and the backlights are turned on and off in the LCD panel by a signal sent on the backlight enable lead (Backlight on). This signal is controlled by the IO chipset (BIOS) and can be caused by events such as the lid closing/opening, screen timeout settings, external monitor display only selected etc.

Check fuse F7 (type 3A_32V_ERBRD3R00X) on the motherboard is OK and not blown

(click on image)

I searched for AIVLO NM-A251 REV 1.0 as searching online this seemed to be the board number for the motherboard (printed on the board itself)

Hopefully a start

Lenovo Thinkpad T450

No Power to Display

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