Page 3 of 5 SRM/RTG Manual 14 December 2007
Revision 2.0
2.) Remove the 4 screws, two each side, from the unit, and set the cover to the side. Leave the wires
attached so that there is access to the printed circuit board. Turn the unit “ON”.
3.) All voltage measurements are made relative to the unit ground. The test point for ground is adjacent to
the –15 and +15 volt test points.
4.) Use a 4-½ digit digital voltmeter such as a Keithley Model 175 Multimeter to measure the voltage on
the 30VTP. Record this voltage as V30.
5.) Measure and record the voltage at the +15V test point as V15.
6.) Calculate and record I(ref) using the formula: I(ref)= V30 * .04054
7.) Calculate and record R (tp1) using the formula R (tp1) = (V15-.236)/ (I (ref)).
8.) Calculate and record I(O) using the formula I(O) = I(ref) x 1.016), (exponent –3)
9.) Calculate and record I(6) using the formula I(6) = I(ref) * .992), (exponent –9)
10.) Turn the unit off and remove the shorting jumper connected to TP1 and its adjacent pin. Measure the
resistance between the +15V test point and TP1 lead closest to R7. Adjust P1 until the measured
resistance is equal to the calculated value RTP1 +/- 1%.
11.) Replace the jumper on TP1 and the adjacent pin. Turn the unit on. Connect a current source (e.g.
Keithley Model 220) to the side of R6 connected to the large round pad in the center of the board.
Apply a current equal to the calculated I (O). Measure the voltage on the test pin marked “OUT” and
adjust P2 until the measured voltage is 0.000 VDC +/- .050 VDC.
12.) Apply a current equal to calculated value I(6) to the same point as in step 11. Measure the voltage on
the test pin marked “OUT”, and adjust P3 until the measured voltage is 6.000 VDC +/- .050 VDC.
13.) Apply a current equal to .003^-9 amperes. Measure the voltage on the test pin marked “OUT”, and
adjust P6 for a reading of 8.5 VDC +/- .05VDC. The 10^12.5 led should be illuminated.
14.) Apply a current equal to .03^-9 amperes. Measure the voltage on the test pin marked “OUT”, and
verify a reading of approximately 7.5 VDC. The 10^12 led should be illuminated.
15.) Measure the voltage on the pin marked +8.000 VDC and adjust P4 for a reading of 8.000 VDC +/- .050
VDC.
16.) Measure the voltage on the pin marked –2.000 VDC and adjust P5 for a reading of –2.000 VDC +/-
.050 VDC.
17.) The calibration procedure is now complete. Place the cover back on the base and replace the screws.
Operating Instructions:
DO NOT operate the SRM/RTG with the battery charger connected. The charger will introduce electrical noise
which will render readings inaccurate.
Turn off the SRM/RTG when it is not being used, and charge ONLY with the supplied charger when the Low
Battery indicator is illuminated, or at the end of the day’s use. Charge for a minimum of 12 hours. Do NOT leave the
charger connected continuously.
SRM mode
1.) The SRM/RTG is extremely easy to operate. Simply turn the unit on in the “SRM” mode, and place
it on the surface to be measured. The illuminated display segment indicates the resistivity on the
surface being measured. To insure accurate readings, place small or thin samples on non-conductive
surfaces (> 10^14 ohms/sq). Ideally, a clean glass surface.
2.) Measurements in the 10^11 to 10^12.5 may require a few seconds for the illuminated display to stabilize.
RTG Mode
1.) Connect the supplied cable from the black banana jack on the rear of the unit to your ESD ground
connection, turn the unit on in the “RTG” mode, and place it on the surface to be measured and read the
display.
2.) Measurements in the 10^11 to 10^12.5 may require a few seconds for the illuminated display to
stabilize.
3.) The indicated reading will be resistance to ground readings.
4.) If grounding cable is not connected to a proper ground, several LEDs in the display may illuminate.
This is normal.
