10. Check External Triggering
a. Equipment setup is given in step 9.
b. Remove the audia signal connection from pin H of the
Vertical Amplifier circuit board and apply the signal to both
the TRIG IN connector on the rear panel of the Type 491
adjust the output for 0.2 volts. (Monitor the output ampli-
d. Change the Type 491 Triggering SOURCE switch to
EXT position and the TIME/DIV switch to .1 s position.
e. Check external triggering. Must trigger with a 20 Hz,
0.2 volt signal applied, with the SLOPE switch in either the
+ or - positions.
kHz. Readjust the output amplitude to 0.2 volts peak to
g. Check triggering-Must trigger with a 100 kHz, 0.2 V
signal in the + and - SLOPE positions.
Fig. 6-12. Adjustments for trigger circuit
on the horizontal display
h. Remove the audio signal from the TRIG IN connector.
circuit board assembly.