T420 no backlight

T400/410/420 and T500/510/520 series specific matters only
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mt12345
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T420 no backlight

#1 Post by mt12345 » Fri Sep 01, 2017 8:37 am

A friend of mine bought T420 with broken screen. After installing new screen it turned out there is no backlight.
Is it faulty inverter? fuse on motherboard? or lcd cable? how to find out?

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Re: T420 no backlight

#2 Post by RealBlackStuff » Fri Sep 01, 2017 8:49 am

Check the fuses F3 (3A) and F19 (0.5A) near the LCD-connector on the mobo.
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mt12345
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Re: T420 no backlight

#3 Post by mt12345 » Fri Sep 01, 2017 12:24 pm

cable connector looks bad
photo:
https://yadi.sk/i/_J_RR43k3MXTYE
would that be the issue?

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Re: T420 no backlight

#4 Post by RealBlackStuff » Fri Sep 01, 2017 1:47 pm

Looks bad indeed, those plugs usually have 30 or 40 contacts, yours looks like 35 or 37?
Also, HD and HD+ screens use different LCD-cables, be warned!
HD 04W1617
HD+ 04W1618

mt12345
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Re: T420 no backlight

#5 Post by mt12345 » Fri Sep 01, 2017 2:03 pm

yes I know about the cables, it's HD 04W1617

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Re: T420 no backlight

#6 Post by mt12345 » Sun Sep 10, 2017 7:09 am

RealBlackStuff wrote:
Fri Sep 01, 2017 8:49 am
Check the fuses F3 (3A) and F19 (0.5A) near the LCD-connector on the mobo.
it was F7 (on the other side).

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