*TB 11-6625-678-35
4-5.
Ammeter Accuracy Using AN/GSM-256
(8) Set Test Instrument TIMER switch to 4
TOPPING and observe that Test Instrument AMPERES
(1) Connect meter calibrator (A 1) output
meter indicates approximately 8.5 amperes. If not,
terminals to rear terminals of Test Instrument ammeter
perform b (2) below. Set the TIMER switch to (6) OFF,
observing
set AC POWER ON-OFF to OFF and disconnect the
correct polarity.
battery.
(2) Using meter calibrator controls in current
b. Adjustments.
mode, check the percent of error for the Test Instrument
(1) Adjust R32 for Test Instrument indication of
indication of + 10. The Test Instrument error will be
15 amperes. (R)
within 2 percent.
(2) Adjust R33 for Test Instrument indication of
(3) Repeat technique of (2) above for Test
8.5 amperes (R)
Instrument indications of +5, -5, and -10. The Test
Instrument error will be within 2 percent.
4-7. Discharge Current. a. Performance Check.
b. Adjustments. No adjustments can be made.
(1) Set Test Instrument AUTOMATIC CYCLE-
MANUAL DISCHARGE switch (S3) to MANUAL
Table 4-2. Ammeter Accuracy
DISCHARGE.
Meter test set
(2) Connect the negative lead of power supply
Test Instrument
output current (amps dc)
(B3) to Test Instrument chassis ground and the positive
ammeter indication (amps)
minimum
maximum
lead to pin 2 of AUTOMATIC CYCLE-MANUAL
+20
19.6
20.4
DISCHARGE (S3-c) switch using cable assemblies B5
+ 15
14.6
15.4
and B6. (Pin 2 is the pin connected to adjustable
+10
9.6
10.4
resistor R31.)
+5
4.6
5.4
(3) Unlock and set variable resistor R31 fully
-51
4.6
5.4
clockwise (maximum resistance).
-10
9.6
10.4
(4) Adjust power supply (B3) for an output of
-15
14.6
15.4
exactly 19 volts.
-202
19.6
20.4
(5) Adjust R31 until relay K4 energizes. (Non-
1
Reverse meter test set leads to unit under test ammeter
reportable adjustment)
2
Reconnect ammeter rear terminal lead upon completion
(6) Lock R31 at this setting, turnoff and
of this check
disconnect the power supply.
b. Adjustments. No further adjustment can be
4-6. Charge Current. a. Performance Check.
made.
(1) Set the Test Instrument AC POWER ON-
OFF switch to OFF.
4-8. Battery Low.
(2) Connect cable assembly (B4) to Test
WARNING
Instrument BATTERY CABLE connector and terminals
Discharge
capacitor
C1
before
of storage battery (B2).
performing this adjustment. DO NOT
NOTE
connect the ac input power cable and
For proper calibration of Test
Cable Assembly, Electrical CX-
Instrument charge current parameter,
9064/ASM-137.
storage battery (B2) should be a
a. Performance Check.
partly
discharged
known
good
(1) Connect power supply (B3) negative lead to
battery.
Test Instrument chassis ground and positive lead to
(3) Set Test Instrument controls as follows:
positive terminal of Test Instrument capacitor C1. (C1 is
(a) SELECTOR switch to MA-5
the large capacitor located on the top rear of the main
(b) AUTOMATIC
CYCLE-MANUAL
chassis.)
DISCHARGE switch to AUTOMATIC CYCLE.
(2) Unlock and set variable resistor R30 fully
(4) Connect the Test Instrument power cable to
clockwise (minimum resistance).
the 115 volt 60 Hz power source.
(3) Adjust power supply (B3) for an output of
(5) Set Test Instrument AC POWER ON-OFF
exactly 19 volts to energize Test Instrument relay K1.
switch to ON.
(4) Adjust R30 clockwise until relay K1
(6) Set Test Instrument TIMER switch to 2
deenergizes. (non-reportable adjustment).
MAIN CHARGE.
(5) Lock R30 for this setting, turn off and
(7) Observe that Test Instrument AMPERES
disconnect the power supply.
meter indicates approximately 15 amperes.
If not,
b. Adjustments. No further adjustments can be
perform b (1) below.
made.
4-9. Final Procedure . a. Deenergize and disconnect
all test equipment and install Test Instrument in
protective cover.
4
