TB 9-6625-1185-24
Table 4. Megohms Meter Check - Continued
Resistance standard
Test instrument
final indication
Resistance
(Ohms)
standard
setting
MEGOHMS
TEST VOLTAGE
(ohms)
MULTIPLIER
VOLTS meter
meter
Min
Max
switch 1620D only
indication
indication
1.0M
1.0
0.5
2.0
.95M
1.05M
1.5M2
1.0
0.5
3.0
1.425M
1.575M
2.5M
1.0
0.5
5.0
2.375M
2.625M
5.0M
1.0
0.5
10.0
4.75M
5.25M
10.0M
1.0
0.5
20.0
9.5M
10.5M
10.0M3
1.0
0.5
2.0
9.5M
10.5M
1Perform
check on model 1620D only.
2Connect
additional resistance standard no. 3 in series with resistance standard no. 2. Include certified value of additional
resistance to final indication.
(17) Turn TI MULTIPLIER switch to X100.
(18) Remove all resistance standards from equipment setup and connect resistance
standard no. 4 for 100 MΩ to TI, using three appropriate leads.
(19) Repeat (9) above.
(20) Press and hold TEST VOLTAGE switch and adjust DC ADJUST control until
VOLT meter indicates 0.5 on upper (MULTIPLY MEGOHMS BY) scale. TI MEGOHMS
meter scale will indicate between 1.9 and 2.1.
(21) Repeat (17) through (20) above, except use MULTIPLIER X1K switch position
and resistance standard no. 5 connected for 1000 MΩ. TI MEGOHMS meter scale will
indicate between 1.9 and 2.1.
(22) Turn TI MULTIPLIER switch to X10K and remove resistance standard no. 5
from setup.
(23) Connect resistance standard no. 1 to TI RX + (plus) and RX - (minus) terminals
using appropriate cable and adapter. Connect TI GUARD terminal to resistance standard case.
(24) Repeat (9) and (20) above. TI MEGOHMS meter scale will indicate between 1.9
and 2.1.
b. Adjustments. Adjust SCALE ADJ (CHK) control (fig. 1) until TI MEGOHMS
meter pointer deflects to 2 (CHK) red line.
10. Final Procedure
a. Deenergize and disconnect all equipment. Reinstall protective cover to TI.
b. Annotate and affix DA label/form in accordance with TB 750-25.
CHANGE 1 7(8 Blank)
