TB 9-4920-454-35
TEST INSTRUMENT
CALIBRATOR
WIDEBAND
A
D
C
B
RPM INPUT
INSTRUMENT CABLE
CONNECTOR
(9) Set RPM switch to N1.
(10) Set calibrator for a 20 mV, 70 Hz wideband output.
NOTE
It may be necessary to temporarily disconnect TI to eliminate
(11) If % RPM indicator does not indicate between 99.9 and 100.1, perform b (4) and
(5) below.
b. Adjustments
(1) Connect frequency counter to TP6 (+) and TP3 (-) on tachometer board (fig. 6). If
frequency counter does not indicate between 97 and 103 s, adjust R71 (fig. 6) for a 100 s
indication.
(2) Connect oscilloscope CH2 input between TP1 (+) and TP3 (fig. 6). If a
symmetrical square wave is not on oscilloscope, adjust R26 (fig. 6) for best symmetrical
10