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N-550B
Table 6: Power Problems
Condition
Battery Low indicator
lights steadily while
-
N
550B is connected to
AC and battery is fully
charged.
-
The N
550B does not
operate when
disconnected from AC
power.
Battery Low indicator
on during DC operation
and an alarm is
sounding.
Recommended Action
Ensure that the N-550B is plugged into an operational
AC outlet and the AC indicator is on.
Check the fuses. The fuses are located in the Power
Supply PCB as indicated in Separating Top and Bottom
Cases on page 54. Replace if necessary.
Open the N-550B as described in Separating Top and
Bottom Cases on page 54. Verify the power supply's
output to the battery while on AC. Disconnect the
battery leads from the battery and connect a DVM to
the battery leads. The voltage measured should be 13.8
VDC to 14.2 VDC and the current should be 500 mA to
600mA with the Power switch off and 750 mA to 830
mA with the Power switch on. Replace power supply if
above values are not met.
Check the cable connection between the Top Enclosure
and the Front Panel PCB. If the connection is good,
replace the Front Panel PCB. See Front Case
Disassembly on page 57.
The battery may be discharged. To recharge the battery,
refer to Battery Charge on page 8. The N-550B may be
used with a less than fully charged battery, but with a
corresponding decrease in operating time from that
charge.
Replace the battery as indicated in Battery Removal on
page 66.
There are 15 minutes or less of usable charge left on the
-
N
550B battery before the
point, if possible, cease use of the N
power, connect it to an AC source and allow it to
recharge (approximately 6 hours). The N
continue to be used while it is recharging.
Troubleshooting
N-550B
shuts off. At this
-
550B on battery
-
550B may
45
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