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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.