Section Ill. REPAIR OF PROBES

TM 11-6665-245-34

(1) Remove A2 PCB as outline in paragraph

away from the board. The pull must be straight.

3-7.

c. Remove the four screws that attach the PCB

(2) Using 3/32 inch allen wrench, loosen the

to the main panel of the radiacmeter.

screw on the flag clamp and the switch clamp. Slide

d. Lift the PCB up from the selector switch, and

assembly and remove from meter.

away from the main panel. Use extreme caution not

(3) Unsolder meter wires. Observe wire color

to break the switch.

and polarity.

e. Install a new PCB using the reverse procedure

(4) Remove the two front hex spacer posts.

of (a) through (d) above. Use extreme caution when

(5) Remove the two rear screws holding meter

installing the new PCB on the shaft of the selector

plate. Retain two rear spacers for reassembly.

switch. Alignment of the wafer switch to the shaft

(6) Unscrew four screws holding meter to

must be exercised with great care. Replace screws

plate. Retain all hardware for reassembly.

and connector.

(7) Reassemble new meter in reverse order.

(8) Turn S1 to OFF position, reset meter flag

3-8. Removal and Replacement of

to OFF-BATT. Reset clamps and tighten setscrews.

Meter Light Assembly and Meter

(9) Check scale registration on all ranges and

(fig. 3-4)

trim meter flag as necessary using long nose pliers.

a. Meter Light Assembly. Replacement of the

3-9. Repair and Replacement of Source

meter illumination lamp bulb is accomplished as

Assembly

follows:

(fig. 3-4)

(1) Open the radiacmeter.

WARNING

(2) Remove the A2 printed circuit board.

(3) Remove two screws and two large spacers

Radioactive material used in the source

holding the meter assembly in place.

assembly can be dangerous if it is broken in-

(4) Note the position of the meter coupling on

to small pieces that can be inhaled or in-

gested. Serious injury can result if these

the rear of the meter. Loosen the meter coupling

small particles get into the body. Be careful

screw and lift the coupling off the rear of the meter.

when removing and replacing the source

This must be done with care and without undue

material. All broken pieces should be ac-

force so as not to damage the coupling or the meter.

counted for and placed in a sealable con-

(5) Loosen the screw at the top of the meter

tainer.

assembly that is used to mount the meter illumina-

a. Remove the source frame which protects the

tion lamp, DS1, to the assembly. Be careful not to

source. Use a putty knife to pry up one edge and

break the meter wire during this operation.

then pull the frame from the bottom of the

(6) Swing the small lamp bracket so that the

radiacmeter case.

lamp is fully exposed.

b. Remove the source material by using the same

(7) Push the lamp out of its mounting from the

procedure as used to remove the source frame.

front of the meter assembly panel.

c. Clean the bottom of the case using a suitable

(8) Install a new lamp by reversing the pro-

solvent.

cedure.

d. Install a new source and source frame. Use

b. Meter Replacement. Replacement of the in-

pliobond and cement to the bottom of the case.

dicating meter is accomplished as follows:

Section Ill. REPAIR OF PROBES

(3) Detach the six screws from the bottom

3-10. Repair of Main Probe and Emitter

housing plate of the light pipe assembly. This will

Follower

separate the bottom area of the light pipe from the

a. Light Pipe and Screen. The replacement of the

housing.

light pipe or screen is accomplished as follows:

(4) Remove the two screws from the light pipe.

(1) Remove the two screws attaching the emit-

(5) Lift the light pipe and screen up and away

ter follower to the light pipe assembly.

from the housing plate. Care should be taken not to

(2) Firmly grip the emitter follower housing in

damage the scintillation screen when removing it

one hand and the light pipe assembly in the other

form the housing plate.

and pull away from each other. It is preferred that

(6) Align the rubber gasket to the bottom

the dismantling of these two units be done in an ex-

housing plate.

tremely dark area so that the photo multiplier tube

(7) Install new screen assembly or light pipe to

is not exposed to light.

the housing plate by using the reverse procedure.

3-7