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T400 after disassemble extremely dark screen/no backlight
Posted: Sat Mar 24, 2012 5:49 pm
by revo75
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!
Re: T400 after disassemble extremely dark screen/no backlight
Posted: Sat Mar 24, 2012 6:17 pm
by twistero
Did you disconnect the AC adapter and remove battery before disassembly? If not, you might have accidentally
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.
Re: T400 after disassemble extremely dark screen/no backlight
Posted: Sat Mar 24, 2012 7:30 pm
by revo75
I removed both. I will run through everything, thanks for the info! is the location of the fuse in the HMM ?
Re: T400 after disassemble extremely dark screen/no backlight
Posted: Sat Mar 24, 2012 8:28 pm
by twistero
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.
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.