Check External Triggering

TM-9-6625-2467-15 - index
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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

and to a test oscilloscope so the signal amplitude may be

monitored.

c. Set the Audio Signal Generator frequency to 20 Hz and

adjust the output for 0.2 volts. (Monitor the output ampli-

tude with the test oscilloscope.)

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.

f. Increase the Audio Signal Generator frequency to 100

kHz. Readjust the output amplitude to 0.2 volts peak to

peak.

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.