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      Flash recovery boot block jumper procedure - NetVista / ThinkCentre

      If power to your computer is interrupted while BIOS is being updated, your computer might not restart correctly. The Clear CMOS/Recovery jumper enables you to restart the system and recover the BIOS. To perform a Flash/BIOS recovery using the Clear CMOS/Recovery jumper, use the following procedure:

      Before proceding, be sure to review the safety information.

      1. Turn off the computer and any attached devices, such as printers, monitors, and external drives.
      2. Unplug all power cords from electrical outlets, and remove the cover.
      3. Locate the Clear CMOS/Recovery jumper on the system board.
      4. If necessary, remove any adapters that impede access to the Clear CMOS/Recovery jumper.
      5. Move the jumper from the standard position (pins 1 and 2) to pins 2 and 3.
      6. Replace any adapters that were removed.
      7. Replace the cover.
      8. Reconnect the power cords for the computer and monitor to electrical outlets.
      9. Insert the POST/BIOS update (flash) diskette into drive A, and turn on the computer and the monitor. The system will begin to beep.
      10. After the update session is completed, there will be no video and the series of beeps will end. Remove the diskette from the diskette drive, and turn off the computer and monitor.
      11. Unplug the power cords from electrical outlets.
      12. Remove the cover.
      13. If necessary, remove any adapters that impede access to the Clear CMOS/Recovery jumper.
      14. Return the Clear CMOS/Recovery jumper to its original position.
      15. Replace any adapters that were removed.
      16. Replace the cover and reconnect any cables that were disconnected.
      17. Turn on the computer to restart the operating system.
      18. You may now want to update the BIOS normally. Refer to the readme.txt file that came with your flash BIOS update.

      Additional information

      • If the power button is pressed and the power light does not come on, then boot block recovery will not work. Inspect power to the system board and replace power supply or system board based on normal problem determination.
      • If the power button is pressed, the power light comes on, but there is no video, try boot block recovery. There are several possible causes. The most common is a corrupt Extended System Configuration Data (ESCD) sector in BIOS. Boot block recovery will fix this problem.
        1. Sometimes the floppy diskette drive will not be read during boot block recovery. In this case, the fans are usually running loudly at full speed. If the floppy drive is not read, the system board must be replaced. This could happen when there are solder cracks on the North Bridge.
        2. If the floppy diskette drive is read, once boot-block finishes, and video does not return, replace the system board.
        3. If video returns, the system will have to be flashed again using the normal flash process to reset the serial number, machine type, and model number in BIOS. This could happen when there are corrupt BIOS sectors.
      • If the power button is pressed and video comes up normally, but a hang occurs in POST before the Windows splash screen, try boot block recovery. This could happen if power was interrupted during a normal flash procedure and BIOS is corrupted.
        1. If the problem remains after boot block recovery, use normal problem determination and replace the system board, if necessary.
        2. If the hang goes away, then the problem is solved.
      • If the power button is pressed and video comes up normally, but a hang occurs on or after the Windows splash screen, it is most likely a driver or operating system error and boot block recovery will not help. Run PC diagnostics. This should not be a planar problem.


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      • Alias ID: MIGR-45385
      • Document ID: HT036407
      • Last Updated :17 Jun 2014
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