T420s i7 with backlight but no image - bad cable or LCD?

T400/410/420 and T500/510/520 series specific matters only
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ji2o0k
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T420s i7 with backlight but no image - bad cable or LCD?

#1 Post by ji2o0k » Wed Feb 15, 2017 11:56 am

Hi all, hoping you can help out.

I just picked up a T420s i7 that has backlight but no image. Any thoughts on what it could be?

I am hoping it is just a bad LCD cable (I have an extra one) or possibly even a bad LCD screen?

I think this will be a great candidate for the IPS WQHD screen mod when the kit becomes available....hopefully soon right RMSmajestic?

Any advice is appreciated - i'll attempt the dissemble this weekend (time permitting)

TPFanatic
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Re: T420s i7 with backlight but no image - bad cable or LCD?

#2 Post by TPFanatic » Wed Feb 15, 2017 12:48 pm

I had a similar predicament with a T410. Disassembling the lid and reseating the LCD cable where it connects to the screen fixed the issue. I had already tried reseating the cable at the motherboard connector and that didn't work.

If you can get the computer into an OS, helpful to have an external monitor, does anything display at all?
Daily driver: lenovo T500 P9700, WUXGA, 8GB
Ultraportable: IBM lenovo X60s
Home theater: lenovo T420

Enable advanced features on older Synaptics touchpads with the registry: http://forum.thinkpads.com/viewtopic.php?f=2&t=122612

ji2o0k
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Joined: Sat Oct 31, 2015 6:25 pm
Location: Toronto, ON Canada

Re: T420s i7 with backlight but no image - bad cable or LCD?

#3 Post by ji2o0k » Wed Feb 15, 2017 1:09 pm

TPFanatic wrote:I had a similar predicament with a T410. Disassembling the lid and reseating the LCD cable where it connects to the screen fixed the issue. I had already tried reseating the cable at the motherboard connector and that didn't work.

If you can get the computer into an OS, helpful to have an external monitor, does anything display at all?
Yes, I hooked it up via vga cable to an external monitor and everything boots up properly (I was able to get into bios etc)....


Ok, I'll try reseating the LCd cable...

ji2o0k
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Posts: 79
Joined: Sat Oct 31, 2015 6:25 pm
Location: Toronto, ON Canada

Re: T420s i7 with backlight but no image - bad cable or LCD?

#4 Post by ji2o0k » Tue Feb 21, 2017 10:15 am

quick update on this issue....

I took apart the T420s this past weekend.....pretty much full dissemble so I could clean out the chasis as well as re-apply some new Arctic Silver 5 thermal paste on the heatsink.....

Took apart the screen\bezel etc....cleaned it with all the dust (compressed air) and swapped out the LCD cable with a confirmed working one.....same issue....backlight works, the brightness can be adjusted using Fn + Home or End but no clear image.

I am thinking it is the LCD screen (not the inverter or a blown fuse) because the brightness works...thoughts?

Purchased the FHD IPS mod kit from RMSMajestic and will do the screen swap, hopefully everything works after the swap!

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