Position the DC circuit breaker to OFF.
through (3) below to sectionalize the fault in the inverter
to a definite location. The checks are arranged to reduce
(2) Open front panel to gain access to the door
unnecessary work and aid in tracing the fault to the basic
interlock switch plunger located on the right side of the
unit responsible for abnormal operation.
door frame (fig. 2-1).
(1) Visual inspection.
Some faults in the
(3) Grasp the plunger and pull it out until it
inverter can be sectionalized to a specific area by merely
clicks into the extended detent. The system is now ready
observing the operating and nonoperating status of the
for power to be applied and tests can be made.
unit e.g., malfunctioning circuit breakers, damaged wires
b. To apply DC power to the inverter from the Deltec
or cables, etc.
2592 Variable DC Power Source or equivalent (para. 6-2)
(2) Operational checks.
make the connections to the input terminals A1TB1 of the
inspection fails to sectionalize a fault in the inverter to a
inverter as shown in figure 6-2.
major item, utilize the troubleshooting results contained in
c. To connect the Deltec 2951 Load Bank or
paragraph 4-10 of this manual.
equivalent (para 6-2) to the inverter make the connections
After the fault has been
to the output terminals A1TB3 (fig. 6-2).
sectionalized to a major item, it is necessary to localize
6-6. Inverter Troubleshooting Chart
the fault to a group of components or circuits within the
The localization procedures found in
troubleshooting chart (para 6-5b), will aid the repairman in
110 vdc is present in the inverter. Do
localizing faults in the inverter. In some cases the
not remove or replace parts, nor
localization procedures will isolate the fault to a
perform continuity or resistance
replaceable component, wire, or piece part. If not, the
checks while primary power is applied
localization procedure will reference the isolation
to the unit.
procedure to be used.
a. Use of the Chart. To use the chart, read down the
6-5. Operating Inverter with Front Panel Open
Symptom column of the troubleshooting chart until the
If the front panel is opened, the door interlock switch will
abnormal symptom or condition is found. Perform the
cause the inverter to shut down, refer to paragraph 5-
corrective actions indicated in the chart until the abnormal
2b(5) for detailed explanation of switch in circuit.
symptom or condition is corrected. Figures 6-1 and FO-3
are parts location diagrams which will aid the
a. Use the following procedure to override the door
maintenance man in locating designated parts.
interlock switch when it is necessary to test or
troubleshoot the inverter which the front panel is open.
b. Inverter Troubleshooting Chart.
Input fuse A1F1 blows when re-
Defective inverter drive A1A2.
Turn circuit breaker A1CB1(FO-1) off
placed or circuit breaker A1CB1
and replace input fuse A1F1 (FO-1) if
trips when reset (1973 model
necessary. Remove connector A1A2J1
(FO-3) from the inverter drive printed
circuit (PC) board and observe the
contacts of relay A1K2 (fig. 6-1) as
circuit breaker A1CB1 (fig. 6-1) is
turned on the second time. A1K2 is the
top relay mounted on the left side of the
heat sink tunnel). If the contacts of
relay A1K1(fig. 6-1) close at turn on, the
problem is probably a defective inverter
drive. Replace inverter drive A1A2 (FO-
3) in its entirety. Refer to paragraphs 6-
8 and 6-9 for repair.