T400 after disassemble extremely dark screen/no backlight

T400/410/420 and T500/510/520 series specific matters only
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revo75
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T400 after disassemble extremely dark screen/no backlight

#1 Post by revo75 » Sat Mar 24, 2012 5:49 pm

Before i knew how to get to the cmos, i started disassembling the T400. After not being able to remove the motherboard i googled and found out how to find the cmos. never needed to take it apart, d'oh! What could have happened that theres no back light. From what i saw at initial power on only the bios logo is barely visible after it goes all back. Any information and/or help would be greatly appreciated. Thanks!

twistero
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Re: T400 after disassemble extremely dark screen/no backlight

#2 Post by twistero » Sat Mar 24, 2012 6:17 pm

Did you disconnect the AC adapter and remove battery before disassembly? If not, you might have accidentally :mrgreen: the backlight fuse.
Other possibilities include the LCD cable/connector, (less likely if you haven't opened up the LCD assembly) the inverter or CCFL.
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revo75
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Joined: Sat Mar 24, 2012 5:40 pm
Location: Atlanta, GA

Re: T400 after disassemble extremely dark screen/no backlight

#3 Post by revo75 » Sat Mar 24, 2012 7:30 pm

I removed both. I will run through everything, thanks for the info! is the location of the fuse in the HMM ?

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Re: T400 after disassemble extremely dark screen/no backlight

#4 Post by twistero » Sat Mar 24, 2012 8:28 pm

The fuses are not listed in the HMM because they are tiny surface-mount components soldered on the motherboard. I assume the standard procedure for dealing with a blown motherboard fuse at Lenovo is to replace the motherboard. :roll:
Maybe you can find the relevant details online, or by looking for components marked with "F[number]" (F1, F2, etc.) on both sides of the motherboard. If you have to test them, completely remove all power sources and use a multimeter on the lowest resistance scale. If the resistance between two ends of a fuse is anything more than a few ohms, the fuse is blown.

Then again, simply reseating the LCD cable connectors might solve your issue.
X60 tablet 6363-P3U, 3GB ram, 128GB SanDisk Extreme SSD, SXGA+ screen, Intel 6300
T61 Frankenpad in 15 inch T60 body, UXGA LED-lit AFFS LCD, T9300, 6GB RAM, NVidia NVS140m, Intel 6205, 128GB Crucial M4 SSD, 1TB HGST HDD + eBay caddy in Ultrabay
701c butterfly, 75MHz 486DX4, 40MB ram, 1GB CF card

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