Question about Motherboards

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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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Re: Dell Latitude C540/C640

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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Re: Dell Latitude C540/C640

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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Re: Dell Latitude C540/C640

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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Dude, Can you send me a Bootable ISO CD of Dell Asset/Service Tag BIOS Reset Tool........Please

Hello, you can download this tool here:


The official method is to contact Dell Technical Support. Dell Technical Support will request the Service Tag and Express Service Code from the bottom of the Latitude. If the current user is not the original Latitude owner, Dell will transfer the used Latitude's registration from the original owner with only the Service Tag and Express Service Code from the tag on the laptop.
  • Dell Inspiron 5100: eeprom 93lc46, password in scan code at 0x310
  • Dell Inspiron 7500: eeprom 24c164
  • Dell Inspiron 8100: eeprom 24c02
  • Dell Latitude C600: eeprom 24c02, password in scan code at 0x00, 0x10 and 0x90
  • Dell Latitude C610: eeprom 24c02, password in scan code at 0x00, 0x10, 0x80 and 0x90
  • Dell Latitude C640: eeprom 24c04, password in scan code at 0x100 and 0x180
  • Dell Latitude CPI: eeprom 24c02, password in scan code at 0x00, 0x10, 0x80
  • Dell D600: eeprom 24c04, password in scan code at 0x110
  • Dell Optiplex: Remove the PSWD jumper
  • For most Dell Dimension desktops, the steps to reset a BIOS password and clear all CMOS settings are:
    • Locate the 3-pin CMOS password reset jumper on the system board.
    • Remove the jumper plug from pins 1 and 2.
    • Place the jumper plug on pins 2 and 3 and wait approximately 5 seconds.
    • Replace the jumper plug on pins 1 and 2.

Try the backdoor password: Dell

The another method is: by Using the Motherboard Jumper: In most motherboards CMOS battery is soldered, which makes it difficult to remove the battery. In this case we use another method.
Almost all motherboards contain a jumper that can clear all CMOS settings along with the BIOS password. The location of this jumper varies depending upon the motherboard brand. You should read your motherboard manual to check its location. If you don't have the manual then look for the jumpers near the CMOS battery. Most of the manufacturer label the jumper as CLR, CLEAR, CLEAR CMOS, etc.
When you find the jumper, look carefully. There will be 3 pins and the jumper will be joining the center pin to either left or right pin. What you need to do, is remove the jumper and join the center pin to the opposite pin. e.g. if the jumper joins center pin to left pin, then remove it and join center pin to right pin. Now wait for a few seconds and then again remove the jumper and join the center pin to left pin.
Make sure to turn the PC off, and remove the battery and power cord
( if it is a laptop ) before you continue.

Here is a picture how it looks like:

The default setting is:pin 1 to 2, to clear cmos: 2 to 3.

Best of luck :-)

Feb 05, 2013 | Motherboards

1 Answer

Having trouble with the cmos, model#PP01L

Remove the Harddrive

Remove the Memory Module Cover.

Disconnect the Reserve Battery cable's connector, from the side of the Reserve Battery. Remove, and replace Reserve Battery.
(CMOS Battery)

Memory Module
Reserve Battery

For additional questions please post in a Comment.


Sep 11, 2012 | Dell Motherboards

1 Answer

Power light flash but laptop will not power up


you can look this page, i think you should consider buy a new battery Dell Latitude D830 , mabe this is a very short moyen.

Nov 12, 2011 | Dell Latitude D830 (HN195 - GU095 - T497J...

1 Answer

I have a Dell Latitude D800. I want to run it on AC power. Do I have to take the battery pack out of it before I ru it on AC power?

Hello Paula, Hi Never remove the battery out when powering with AC, your Dell will get busted, run ac with the battery. The AC power produces a voltage above the normal operating voltage of the Dell, the over voltage is for charging the battery and powering the DELL, if you remove the battery, the over voltage will bust the laptop in seconds. So operate the laptop with AC and battery.

Feb 11, 2011 | Motherboards

1 Answer

D600 Powers up via Adapter / Batteries good / Never charges

This is a motherboard issue. Go to Dell's website and click the Technical Service link ...

You can check to see if it is still under warranty and depending on whether it is or not, proceed from there.

Any Dell Certified Tech can easily replace your board for you in a matter of about an hour.

Jun 12, 2009 | Dell (04U621) for Latitude D600, Inspiron...

2 Answers

Dell latitude c600, battery not charging even charging sign is shown in windows (battery is ok and checked by another dell laptop) whats problem?

hi im josh in cebu phils.may i help you. friend try to check the small wire white near the batt.or check the connections if it is not shorted or disconnected. or try to replace new batt. good luck

Feb 22, 2009 | Dell C600 (002UH) Motherboard

1 Answer

Install battery on dell latitude C640 laptop

The reserve ( or CMOS ) battery for this model is attached to the motherboard. To gain access to this, you must first remove all of the following....

Remove the following components first:
Then you will have access to the battery. see photo.
If you are not familiar with Laptop disassembly and repair, this is a huge job, and you may want to consider having a technician install this for you.

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Oct 16, 2008 | Motherboards

2 Answers

DELL d600 model pp01l

If your motherboard traces are damaged, I would highly recommend replace the board. This model laptop can have considerably high current running through that jack and traces. if anything is weak it will burn through.

Or take it to a electronics specialist.

Oct 11, 2008 | Dell C600 (002UH) Motherboard

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