Section IV. TESTING REPAIRED EQUIPMENT

TM 11-6665-245-34

(2) Using a heat sink, unsolder tube

(5) Slide replacement PCB into tube

socket assembly leads from PCB.

socket clamp and reverse process of c.(1) and c.(2)

(3) Replace or repair tube socket, then

above.

solder leads back onto PCB.

d. Replacement of Tube Socket Assembly.

e. Replacement of Non-Electronic Parts.

(1) Remove PM tube from tube socket

Replace all remaining parts in kind since they are

(para. 3-12. b).

non-repairable.

Section IV. TESTING REPAIRED EQUIPMENT

(5) The meter indication should not rise

3-13. Source Test

above 250 cpm. If the meter reading exceeds 250

a. Remove the main probe "window" protec-

cpm, immediately remove the probe from the light

tive cover.

source.

b. Set the radiacmeter selector switch to 10K.

c. U n c o u p l e t h e m a i n p r o b e f r o m t h e

3-15. Calibration of the Radiacmeter

radiacmeter and position it against the check

The radiacmeter is calibrated with the main probe

source on the radiacmeter case bottom.

attached (the aux probe is not calibrated) using

d. Meter should read 6000 & 1200 cpm if the

Radiac Calibrator AN/U DM-7C. Prepare the

source is to be considered serviceable.

r a d i a c m e t e r by installing batteries (selector

3-14. Light-Leak Test

switch: OFF) and removing the cover. Locate the

two adjustable potentiometers R18 and R26 and

Main Probe.

then proceed below:

(1) Remove the main probe "window"

a. Check the mechanical zero of the meter

protective cover.

and adjust if necessary.

(2) Set radiacmeter main probe down on a

b. Turn R18 (level control fully

flat surface so that the "window" is covered.

counterclockwise.

(3) Set the selector switch in the 100K

position.

(4) Pick up the main probe and slowly ex-

WARNING

pose it to light while watching the meter. If the

High voltages are exposed when the

meter reading begins to rise when the probe face

radiacmeter case is removed and the

is exposed to light, immediately remove the probe

equipment is turned on. Locate the high

from the light.

v o l t a g e points on the circuit board

(5) There should not be any meter indica-

BEFORE truning the radiacmeteron. Be

tion when the probe is exposed to light.

careful to avoid contact with the ex-

b. Aux Probe. Test the aux probe light barrier

posed high voltage while making ad-

for light leaks by inspection rather than the elec-

justments. Injury from electrical shock

trical method used for the main probe (a. above).

may result from touching high voltage.

Use a suitable light source (flashlight or hand

lamp) in a darkened room and direct the light on

c. Set selector switch to 10K position. Meter

one side of the probe barrier while inspecting for

should read upscale a s-mall amount. Adjust R18

light leaks on the other. As an alternate method,

clockwise to reduce the meter reading to zero.

remove the four screws (Figure 3-6) that hold the

d. Refer to TM 11-6665-247-10 (AN/U DM-7C) for

cover assembly to the aux probe chamber and in-

instructions on setting up the AN/U DM-7C for

spect the cover assembly for light leaks with a

calibrating the AN/PDR-56F.

strong light.

c. X-Ray Probe.

NOTE

(1) Connect the x-ray probe to the

A l w a y s u s e t h e i n s t r u c t i o n i n TM

radiacmeter.

11-6665-247-10 for setting up or packing

(2) Cover the window of the x-ray probe to

away the calibrator.

prevent entry of light.

(3) Set the selector switch on the

e. Set up the calibrator using attenuator #1

radiacmeter to the 1K position.

and source A. Remember to remove the main pro-

(4) Pick up the x-ray probe and slowly ex-

be window guard from the main probe before set-

pose it to a suitable light source (flashlight or

ting it in the AN/U DM-7C probe positioner.

hand lamp) while watching the meter.

3-11

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