Section 5: Troubleshooting
5-3
5.6.1 Power
Power problems are related to AC and/or DC. Table 5-2 lists recommended
actions to power problems.
Table 5-2: Power Problems
Condition
Recommended Action
1. BATTERY LOW
indicator lights
steadily while NPB-
190 is connected to
AC and battery is
fully charged.
1. Ensure that the NPB-190 is plugged into an operational AC
outlet and the AC indicator is on.
2. Check the fuses. The Power Entry Module contains the
fuses as indicated in paragraph 6.3 and Figure 6-3 of the
Disassembly Guide
section. Replace if necessary.
3. Open the monitor as described in section 6. Verify power
supply’s output to the battery while on AC. Disconnect the
battery leads from the battery and connect a DVM to them.
The voltage measured should be 6.8 VDC + 0.15 and the
current should be 400 mA + 80 mA. Replace power supply
if above values are not met.
4. Check the cable connection from the bottom enclosure to
the UIF PCB, as instructed in paragraph 6.5 of the
Disassembly Guide
section. If the connection is good,
replace the UIF PCB.
2. The NPB-190 does
not operate when
disconnected from
AC power.
1. The battery may be discharged. To recharge the battery,
refer to paragraph 3.3.1, Battery Charge. The monitor may
be used with a less than fully charged battery but with a
corresponding decrease in operating time from that charge.
2. If the battery fails to hold a charge, replace the battery as
indicated in Section 6,
Disassembly Guide
.
3. BATTERY LOW
indicator on during
DC operation and
an alarm is
sounding.
There are 15 minutes or less of usable charge left on the
NPB-190 battery before the instrument shuts off. At this
point, if possible, cease use of the NPB-190 on battery
power, connect it to an AC source, and allow it to recharge.
The full recharge takes 14 hours. The NPB-190 may
continue to be used while it is recharging.
4. Battery does not
charge.
1. Replace battery if more than 2 years old.
2. Open the monitor as described in Section 6. Verify power
supply’s output to the battery while on AC. Disconnect the
battery leads from the battery and connect a DVM to them.
The voltage measured should be 6.8 VDC ± 0.15 and the
current should be 400 mA ± 80 mA. Replace power supply
if above values are not met.
