WBJI DSM-502
PAGE 9
6.0
MAINTENANCE
GENERAL:
The DSM-502 Digital Survey Meter has an Internal Probe that operate independently as
CPM/CPS RATEMETER, DOSE CALIBRATED RATEMETER, SCALERWITH TIMED
COUNTING FUNCTIONS . Once the instrument has been calibrated the only operator
intervention required is to select the probe with the MAIN SELECTORS SWITCH ON THE
FRONT PANEL. No external devices are required to calibrate the system except a NIST
traceable radioactive source and electronic pulse generator. ALL CONTROLS
NECESSARY TO CALIBRATE THE DSM-502 ARE LOCATED ON THE PC BOARDS OF
THE SYSTEM.
6.1
LOCATION AND FUNCTION OF CALIBRATION CONTROLS
GENERAL:
The calibration procedure for the DSM-502 utilizes only 3 potentiometers and 2 switches to
calibrate all of the DSM-502 functions. FIGURE 1 SHOWS THE GENERAL LOCATION
OF THESE CONTROLS. SW4 located on the left side of the top pc board (next to SW5)
selects the function to be calibrated. These switch positions are as follows:
POSITION 0 NORMAL OPERATING POSITION
POSITION 1 DISPLAY & EDIT COUNT TIME 0 - 2550 SECONDS (10 SECOND INCREMENTS – ADJ
–
P1
POSITION 2 DISPLAY & EDIT OPERATIONAL ALARM (5% - 95%) ADJ – P1 COARSE – P2 FINE
POSITION 3 DISPLAY & EDIT OVER RANGE ALARM ADJ – P1 COARSE – P2 FINE
POSITION 4 DISPLAY & EDIT CALIBRATION CONSTANT – ADJ – P1 COARSE – P2 FINE – P3
TENTHS
POSITION 5 DISPLAY & EDIT DEAD TIME - ADJ – P3
POSITION 6 DISPLAY & EDIT HIGH VOLTAGE - MAIN SELECTOR TO #1 PROBE – ADJ #1 HV
POSITION 7 DISPLAYS SOFTWARE NUMBER INSTALLED IN INSTRUMENT
POSITION 8 DISPLAY & EDIT FAST & SLOW TC – SET TO FAST ADJ P1 TO (10 – 250 SECONDS)
SET TO SLOW ADJ P1 TO (10 – 250 SECONDS
POSITION 9 DISPLAY & EDIT LCD REFRESH RATE (8 = 0.8 SECONDS TO 30 = 3.0 SECONDS)
ADJ P1 TO DESIRED REFRESH RATE
SW5 (located next to SW4) is utilized to ACTIVATE & SAVE CALIBRATION SETTINGS
(
CAL is visible in the upper center of the display when SW5 activates the calibration
function
) the function selected by SW4 and then save the data once the function has been
calibrated into the meters data base. Once a function has been selected by SW4 and
activated by SW5 the potentiometers P1, P2 & P3 are utilized to input the calibration data.
Once these potentiometers have calibrated the function SW5 is depressed and the data is
saved. This process is repeated for each SW4 position using the same P1, P2, & P3 for all
data input.
FIGURE 2 SHOWS THE LOCATION OF ALL THE CALIBRATION COMPONENTS.
6.2
ADJUSTING THE METER FOR CPM/CPS AND R/Sv OPERATION
6.2.1
The switches that adjust the DSM-502 for Roentgen or Sieverts are located on the LCD pc
board. To access these switches remove the DSM-502 from its housing . Looking at the
bottom of the instrument with the LCD at the top the CPM/CPS switch is on the left side of
the LCD pc board. The side of the board near the LCD will have CPS and CPM slide the
small black switch lever towards the type operation desired.
6.2.2
The switch that selects Roentgen or Sieverts is on the right side of the LCD pc board is
located directly above the push button switch SW5. Slide the small black switch lever in the
direction of the desired units of measurement (mR/hr or Sieverts).
6.2.3
This completes the adjustment of the DOSE UNITS AND COUNTING UNITS THAT WILL
BE DISPLAYED ON THE LCD.