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    AST RESEARCH, INC.         TECHNICAL BULLETIN # 0974                9-14-94

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                BRAVO NB AND ADVANTAGE! EXPLORER BATTERY CHARGING ISSUE

    PROBLEM:        The Bravo NB and the Advantage! Explorer system batteries can
                    discharge below the minimum voltage threshold due to lack of
                    use.

                    The problem is observed when the AC adapter is plugged-in and
                    the battery charge light stays on approximately 12 minutes.
                    The battery LED then begins to blink at about 2 times per
                    second.

                    Battery packs stored outside of a system for an extended time
                    will discharge to a voltage of approximately 5 volts, while
                    packs that remain in systems can get as low as 1 volt.

    CAUSE:          This discharge is a normal characteristic of battery
                    technology.  While inserted in the system, with the system
                    off, the system is sourcing about 0.44mA from the battery.
                    This current powers the circuitry needed to detect the power
                    switch activity.

                    The system trickle charges the battery for approximately 12
                    minutes and looks at the battery voltage.  If the voltage is
                    above the threshold, full charge begins.  If below the
                    threshold, the pack is thought to be defective and the twice
                    per second blink is to indicate a problem.  The minimum
                    voltage threshold is used to prevent full current charging of a
                    defective pack.

    SYSTEMS
    AFFECTED:           AST
                    PART NUMBER             DESCRIPTION

                    501262-XXX      ADVANTAGE! EXPLORER 486SX/25 MONO
                    501263-XXX      ADVANTAGE! EXPLORER 486SX/25 COLOR
                    501264-XXX      ADVANTAGE! EXPLORER 486SX/25 COLORPLUS
                    501404-XXX      ADVANTAGE! EXPLORER 486SX/33 MONO
                    501405-XXX      ADVANTAGE! EXPLORER 486SX/33 COLOR STN
                    501247-XXX      BRAVO NB 486SX/25 MONO
                    501248-XXX      BRAVO NB 486SX/25 COLOR
                    501249-XXX      BRAVO NB 486SX/25 COLORPLUS
                    501373-XXX      BRAVO NB 486SX/33 MONO/COLOR STN

    SPARE PARTS
    AFFECTED:       501253-001      BRAVO NB NiMH BATTERY
                    501268-001      ADVANTAGE! EXPLORER NiMH BATTERY (BLACK)

    SOLUTION:       To bring the battery up to the minimum voltage threshold for a
                    full charge, plug the AC adapter and then reinsert it, and
                    allow 12 more minutes of trickle charging (until the battery
                    LED starts to flash rapidly).  By the fourth cycle, the battery
                    should be at the minimum voltage threshold to allow for a full
                    charge.

                    Once the battery begins charging (beyond the 12 minute cycle
                    time), and the main battery LED will not flash rapidly, the
                    system will charge the battery.  If the battery LED light
                    continues to flash rapidly after the fourth trickle charging
                    cycle, call AST Product Support at 1-800-727-1278 for a
                    replacement battery.

                    NOTE: To optimize battery performance refer to your user’s
                    manual.