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Dell Latitude C540/C640

Hello.. I recently received a Dell Latitude C540/640 PP01L Laptop whichwon't power on with a adapter nor a charged battery. Considered themotherboard as the culprit after a number of troubleshooting attempts..Upon disassembly & close inspection of the motherboard's powercircuit it seems the motherboard has been altered/tampered with.. onthe left of the processor socket there are 8 Fairchild (FDS) Mosfets..out of the 8 there are 4 FDS6694 30V DC Converter Powertrench Mosfetsthat are connected/soldered together via a resistor.. one resistorattached to 2 Mosfets (2 resistors used for 4) Don't really know whatpurpose this trick was used for, may be the company it went topreviously messed up just cause the customer who happens to be a closerelative won't pay them as much as they wanted? anyway, i did manage toremove the unwanted resistors & tried to see if the laptop workswithout, but it doesn't.. so im assuming i'm dealing with some shortedmosfets needing replacement? what else do i need to look for to getthis not so fortunate critter to live again?

Thanks :-)

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  • hookedonjcfj Feb 13, 2008

    C640 shut down suddenly and could't turn on. Traced defect to FL1 after the DC power connect on the motherboard. In the process of desoldering it, continuity was restored and when tested the laptop powered up. I have done this twice during the last three months due to the unavailability of a suitable replacement.

  • Rsharp79 Jul 24, 2008

    Got a PP01L As well with the same problem(s), in a Latitude C600.

    Powers up for just a few seconds, and doesn't even make it to BIOS, she took it to a shop and they asked her for her BIOS password which is common on dell laptops and almost impossible to reset, I pulled the hard drive, DVD rom, and the battery and still would not boot. Stupid dells anyone found a fix for this yet? Besides replacing the motherboard?

  • Anonymous Nov 29, 2008

    same happened on 600m and d600, anyone find out what component fl1 is:

  • rcadiz Mar 10, 2009

    Having same problem with Inspiron 1501. Also traced back to FL1. What component did this USED to be ? Little fried and disintegrated right now.

  • breezy1994 Apr 15, 2009

    I have the same problem on a Dell D600! I traced it back to the component identified as "FL1". It has no identifying marks on the chip and mine is bad. Can someone tell me what it is? If we new the specs of the component it would be simple to replace or make a suitable replacement. I figure it could be replaced with a manufactured or homemade one for far less than what a new motherboard costs.



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Ya u can try to chnag ethose how much is the mobo on ebay for one of these also new mobo may be your best bet even fixing them still may not work for u thats 50 50 chance

Posted on Jan 22, 2008

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I have similar problem with my 540/640. Doesn't start up, led doesn't indicate it's being charged.
One obvious fault I've found is the integrateg circuit next to the power supply socket on the motherboard- it's broken in half and burned through.
Could somebody tell me what is written on it, so I could find replacement.
It sais P2(?)5AZ and something else.
If you could look into it I would be greatful

Posted on Feb 09, 2010

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My Laptop charger blinks whenever i plug it witout battery. Is it possible to on Laptop withut battery. How much is the battery for the model No. PP01L C540/C640

Posted on Sep 23, 2008

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Posted on Jan 02, 2017

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Wow Buddy. I'm impressed with your work here.
I have seen many boards which were oem, which had what appeared to be 'add on' circuitry. It's common when a problem arises in a product, which they've already had a million of manufactured. Otherwise, maybe the NSA, CIA, or MA Bell doing a little snooping?
Ok just kidding.
Assuming the circuitry which was replaced was still there, I've experienced a couple of "no power" issues on these models.
Bad power board.
AC adapter socket unsoldered from board.
Dead short between motherboard and palmrest/case.
Bad memory.
Burned capacitors.
Best thing since it's apart already, just order another board and you'r good to go.
I sell the same board at my shop for 75-100.00 US.
If the processor's good, then you should be good to go.
Good luck

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