TB 55-4920-389-34
a single motionless image of the black tape appears on stroboscope. Adjust the test instrument TACH CAL HIGH
potentiometer (located behind the tachometer indicator) for 4500 rpm on the tachometer.
Test Instrument Tachometer Indicator
Stroboscope (A1)
Indications (RPM)
Indications (RPM)
MIN
MAX
1500
1350
1650
2000
1850
2150
3000
2850
3150
4500
4450
4650
4-2. AC Ammeter Check.
a. Performance Check.
(1) Connect meter calibrator (A2) test leads B1 and B2 to the test instrument AC ammeter test jacks.
(2) Set test instrument AC ammeter RANGE SEL switch to LOW position.
(3) Adjust meter calibrator for 2 amperes indication on test instrument AC ammeter. Meter calibrator will indicate
between 1.925 and 2.075 amperes ac.
(4) Set test instrument AC ammeter RANGE SEL switch to HIGH position.
(5) Adjust meter calibrator for each of the test instrument AC ammeter indications as listed in table 4-2. Meter
calibrator will indicate within the limits specified.
b. Adjustments. No adjustments can be made.
TABLE 4-2. AC AMMETER CHECK
Test Instrument AC Ammeter Indications
Meter Calibrator Indication (amps ac)
(amps ac)
MIN
MAX
3
2.85
3.15
4
3.85
4.15
5
4.85
5.15
5