System Self-Test Function Theory

TM 9-1240-369-34

reset signals are split in two; the latter, manual reset

malfunction circuitry provides the capability to isolate

select, is applied only to the set logic card. The last

problems which occur in the system.

Certain

three signals (first, second. and last) control the counter

malfunctions are automatically detected. Then the MALF

selection logic circuits.

light is illuminated the type of malfunction will be

(2) R/T control unit. The R/T control unit consists of

indicated on the last numeral of the range (meters)

indicator. Malfunction indications and probable troubles

two switches. RANGE and RESET, with backlighted

are assigned as follows:

indicators. The RANGE switch is a pushbtutton type

switch which fires the laser. The RESET switch is also a

MALF 4 (Power Sup-

PFN Over charge

pushbutton type switch that resets the system prior to the

ply Control Unit)

PMT High Voltage

next ranging sequence after any ranging operation. The

PFN Charge (fire signal)

RESET switch has to be activated before the transmitter

MALF 3 (receiver-

A-Trigger and A-Trigger

canbe fired after the initial firing allowing system turn-on.

transmitter unit)

The R/T control unit also has two control knobs, azimuth

MALF 2 (Iower Sup-

Reply gating and

and elevation. These controls are used to center the

ply control Unit)

Counters

telescope on the target. A RTCL ILLUM control is

MALF 1 (Battery

Battery charger

provided to light the telescope reticle for low light

power supply unit)

operations.

(after lasing MALF 1 will not be present until

RESET switch on R/T control unit is pressed)

1-8. System Self-Test Function Theory.

a. General. The laser range finder contains two

The second category of self-test circuitry is used in the

categories of self-test circuitry. Malfunctions in four

test mode of operation; to provide comprehensive

specific area of the system are monitored during the

simulation of firing the laser and receiving up to four

operational mode --ON-- to provide indications of trouble

replies without actually transmitting a laser beam.

to the vehicle crew, and general clues to the trouble area

to the turret mechanic as well as the crew. The

1-10