TM 55-4920-431-13
MAINTENANCE
PROCEDURES
Section IV.
Gain access to inside the case for
4-7. Access to Inside Case for Maintenance.
maintenance purposes, as follows:
Turn pressure equalizer knob to OPEN.
a.
b.
Open two butterfly fasteners on front of case. Open lid, fold back, and
remove from case.
Turn pressure equalizer knob to CLOSE.
c.
d.
Remove ten screws (17, figure 5-1) and washers (18) securing front panel
assembly (16) to case (26).
e.
Lift front panel assembly from case and lay over for access to components
for maintenance.
After completion of maintenance, lift front panel assembly back into position
f.
in case aligning holes for retaining screws.
Reinstall ten screws and washers.
g.
Close lid and secure butterfly fasteners.
h.
Install lid on case.
4-8. Testing. The following paragraphs describe tests that may be performed in
conjunction with troubleshooting to isolate a faulty component or wiring.
4-9. Test Switches.
Refer to wiring diagram, figure FO-2. Test switches as follows:
a. Gain access to inside of case per paragraph 4-7.
Be sure outside electrical power is not applied
to tester during continuity checks. Damage to
meters and other components can result.
b. Test MASTER Switch (S7).
1.
Unsolder wire no. 109 at switch.
2.
Connect VOM + lead to switch (S7) center terminal and - lead to switch
(S7) lower terminal.
3. With switch toggle in down position, the VOM should read infinite ohms.
With switch toggle in up position, the VOM should read zero ohms.
4. Disconnect VOM and resolder wire no. 109.
c. Test START/RUN/STOP Switch (S1).
Connect VOM + lead to switch (S1) center terminal and - lead to switch
1.
(S1) lower terminal.
