X200 Latitude CMOS Reset

Question

I have an X200 Latitude laptop that I would like to give to my daughter to use for college, I've made some upgrades, increased memory to 640mb, larger battery and internal wireless upgrade.  Unfortunately I let the laptop sit for about a year and this discharged the CMOS reserve battery, after replacing the reserve battery, every time I change the battery pack it gives the RTC error at boot.  I upgraded the BIOS to the latest and greatest, but it still returns the same error.  I remember their use to be a way either internally (by the CMOS reset jumper) or externally (series of keys pressed at boot) that would clear/reset the CMOS, I've tried everything I know if anyone can assist me with this it would certainly make my little girl happy...Thanks..jabmicros1

ejn63 · Answer

If this is happening when you disconnect the main battery, the CMOS battery is dead - it's not doing its job.

jabmicros1 · Answer

This is what I originally thought as well, I replaced the 4 cell 2M728 @ 4.8 volts it tested well, the replacement is the same part number 2M728 however it is a 5 cell 6.0 volt. I tested the battery after connection (2 days) and it tested good as well, the batteries are technically sound, I've encountered this before with a C610, however after installing the new CMOS battery I cleared the CMOS with the jumper and the RTC resumed normal functionality. However with this unit there are no visible jumpers on the MB, so I believe it is a boot up sequence (keystroke depression at power up) like the old days, that is why I started this thread in hopes of reaching out to the community at large to find this sequence...Thanks..jabmicros1

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leduke30 · Answer

Alt+ F on page 1 of BIOS Setup restores Factory defaults for the BIOS version you are using.

jabmicros1 · Answer

Tried it at ‘Main’ page/tab in BIOS setup, still the same results, also tried restoring factory defaults (F9), with same results. Below is the following error message I receive after removing the battery pack for approximately 5 seconds during POST:

0271: Check Date and Time Settings

Warning

0251: System CMOS Checksum Bad – Default Configuration Used

leduke30 · Answer

Well, you have done what the Service manual says to do when you replace that battery and it still is not working. The battery you replaced and the new one both check to be good. It is obviously not a short somewhere in the circuit or the batteries would be discharged. It is sounding like a no-connection problem on the board and if so you are probably looking at another board purchase or perhaps a board repair by an experienced tech. You can inspect the receptacle on the board for a bent or broken pin, but if present, that would require a tech to resolder another one as a replacement. I wish I had something more cheerful to say, BUT???

jabmicros1 · Answer

I will pull the MB and inspect the pins, visually everything looks ok, but I believe you are correct, for whatever reason it just doesn’t see the presents of a reserve battery source.  Any suggestions on where I could get this looked at?  Thank you for your help…jabmicros1.

ejn63 · Answer

Depending on whether its an 800 or 933 CPU, the boards cost about $130-150:

http://www.parts-people.com/index.php?action=category&id=140&subid=108

The CPU is soldered to the board on these, but if you can replace the board yourself the cost isn't too bad.

leduke30 · Answer

HERE is one of the better boards for $73. I doubt you will find a tech to repair your present board for less.

jabmicros1 · Answer

Thank you all for your help in resolving this, it wasn’t until I removed the MB and saw a small circular heat shrink covered part that was external of the MB that I started to investigate.  What I discovered was that this item (once I separated it from the MB) was in fact the RTC – battery, I removed the heat shrink and uncovered a 3-volt CR2025 Sony battery.  I removed the spot soldered tabs and replaced the CR2025 with a CR2032, re-soldered the tabs to the CR2032, covered with heat shrink and placed in the area reserved for this battery on the MB.  Placed the MB and parts back into the laptop and tested by setting the RTC, through the CMOS settings, stopping the system and removing the battery pack for 15 minutes, replaced the battery and restarted the laptop.  ‘Boom Shaka Laka’ that was it, the laptop is now working 100% and ready to be handed off to my daughter…jabmicros1

kostis giapanos · Answer

hi, i seem to have a similar problem with batteries with the difference that i cannot go to the bios. the screen just flash when i press the power on switch and the power led is on. also i didnt understand how the cmos is to be reset? Just by removing the main battery, for how long? Thanks

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X200 Latitude CMOS Reset

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