(23) Release PRESS TO TEST switch on the PFN
PFN voltage control) on the power supply control unit
and adjust (10) the PFN voltage control in the power
(24) Set LASER MODE CONTROL switch in the
supply control unit as described in the subsequent steps.
commander's control unit to OFF.
(25) Disconnect PFN charge ammeter cable from
PFN charge ammeter and power supply unit.
Do not turn PFN voltage control too high
(20) Disconnect the tester cable from the R/T tester
as damage to the laser optics might
and the PFN charge ammeter cable.
occur. Turning R10 clockwise increases
(27) Loosen the four screws (7) that secure the R/T
the energy output of the laser range
tester to the tester adapter.
finder, causing the meter needle to move
(28) Remove the three screws (3) and three washers
to the right. If it is necessary to increase
(4) that secure the tester adapter to the receiver-
the laser energy output, do so in steps
not greater than one full clockwise turn
(29) Lubricate screw (3) with grease, MIL-G4343.
at a time, to avoid damage to the optics.
(30) Install the three screws (3) and three washers
(4) on the front of the receiver-transmitter unit (8).
(20) Turn the PFN voltage control a maximum of
(31) Install PFN ADJ screw on power supply control
one full clockwise turn and observe the indication on the
RCVR-XMTR STATUS meter.
(32) Close cover assembly (2) and latch (1).
(21) Press PRESS TO TEST switch on PFN charge
(33) Install power supply control unit, power supply
ammeter. If the PFN charge ammeter indicates more
control unit ballistic connector cover, and power supply
than 82 microamperes when the R/T tester indicates in
control unit cover as described in TM 9-23-230-12.
the red band return the receiver-transmitter unit and
power supply unit to GS maintenance for repair.
2-7. Troubleshooting of R / T Control
(22) Repeat step 20 until RCVR-XMTR STATUS
meter indicates in the red. If adjustment cannot be
a. Test Setup. Set up hot mock-up as described in
accomplished, the receiver-transmitter unit must be
replaced. Go to step (24).
troubleshooting procedures for the R/T control unit are
If the above malfunction is observed at
contained in table 2-5. This table is to be used after
general support, replace the transmitter
organizational maintenance has determined the
component assembly (71, fig. 3-6) and
malfunction exists in the R/T control unit.
repeat this procedure.
Table 2-5. Troubleshooting of R/T Control C-8728/VVG-1 (A75)
Ensure that power is off when installing or removing units in hot mock-up, or installing or
removing components or assemblies in units.
Unless otherwise specified, all controls, switches, and indicators are on the A75 unit and
lamp illumination is adjusted for maximum brightness. Extender card test points are
connected to corresponding circuit card pin numbers.
RESET or RANGE lamp does
Defective lamp, defective switch, or
1. Install failed unit in hot mock-up.
2. Perform portion of checkout
3. Replace lamp associated with malfunction
4. Perform step 2. If malfunction is
corrected, remove unit from hot mock-up. If
malfunction is not corrected, continue with