Section V Model 175A
Paragraphs 5-21 to 5-32
5-21. CALIBRATOR. b. Connect the DO A (AC- I) Probe from
vertical INPUT to CALIBRATOR 10 VOLT output.
a. Connect the Calibration Generator to vertical
INPUT and set output for 10 volts peak-to-peak.
c. Loosen locknut at rear of probe and rotate rear
plastic flange with respect to cable. The waveform
b. Set:
should change from one with overshoot to one with
SWEEP TIME .......... 2 MSEC/CM undershoot.
HORIZONTAL DISPLAY ......... X1
Vertical SENSITIVITY ..... 1 VOLT/CM d. Adjust probe for best square wave and tighten
Vertical Sensitivity locknut. Note vertical amplitude of display.
VERNIER .......... counterclockwise
e. Disconnect probe from vertical INPUT and
c. Rotate vertical sensitivity VERNIER clockwise CALIBRATOR.
for exactly 5 cm of vertical deflection.
f. Connect CALIBRATOR 1 VOLT output directly
d. Disconnect Calibration Generator and connect to vertical INPUT. The vertical amplitude of the
CALIBRATOR 10 VOLT output to vertical INPUT. display should be equal to that noted in step d.
Vertical deflection should be 5 cm k0.05 cm if am-
bient temperature is between 15°C and 35°C (50°F g. Disconnect CALIBRATOR from vertical INPUT.
and 95°F). Vertical deflection should be 5 cm *0.15
cm if ambient temperature is between 0°C and 15°C 5-25. ADJUSTMENTS.
or 35°C and 55°C (32°F and 50°F or 95°F and
5-26. This section covers internal adjustments of
130°F). the Model 175A. If difficulty is encountered in making
5- 22. INTENSITY MODULATION. any adjustment, refer to paragraph 5-67 for trouble-
shooting procedures. A condensed adjustment pro-
a. Connect the 600-ohm output of the Square Wave cedure is given in table 5-9.
Generator to vertical INPUT and INTENSITY MOD-
ULATION INPUT.
5-27. EQUIPMENT NEEDED FOR ADJUSTMENTS.
b. Set 600-ohm output to maximum and frequency
5-28. In table 5-1, items 3 through 13 are the test
to 10 kc.
instruments recommended to make the adjustments
c. Set: outlined in this section. Equipment with equivalent
characteristics may be substituted. The special
SWEEP TIME .......... 20 pSEC/CM
Vertical SENSITIVITY .... 10 VOLTS/CM horizontal Test Plug shown in figure 5-1 is required
to test the main vertical amplifier scanner outputs.
INTENSITY MODULATION ........ EXT
Vertical POLARITY ........... +UP
5-29. LOCATION OF ADJUSTMENTS.
d. The top of the square wave should beintensified
with respect to the bottom. 5-30. Figures 5-2 and 5-3 show the location of tubes
and adjustments in the Model 175A. These diagrams
e. Disconnect Square Wave Generator. Return are screened on the inside of the top and bottom
covers of the instrument.
INTENSITY MODULATION to INT.
5-23. SWEEP AND GATE OUTPUT 5-31. PRELIMINARY SETTINGS.
(OPTIONAL FEATURE). 5-32. Install vertical and horizontal plug-in units
in their compartments in the Model 175A. If the
a. Set SWEEP MODE to FREE RUN. vertical plug-in unit has more than one channel,
select CHANNEL A and use channel A controls.
b. Trigger Test Oscilloscope with gate output
signal from Model 175A.
a. Make the following settings on the panel of the
c. Observe SWEEP OUTPUT signal on Test Os- vertical plug-in unit.
cilloscope. Signal should be a linear ramp of approx- AC-DC.. ................. AC
imately -2.5 to +2.5 volts on all SWEEP TIME
settings. VERNIER ................. CAL
d. Observe GATE OUTPUT signal on Test Oscil- b. Depending on model number, make the follow-
loscope. Signal should be approximately 4 volts for ing settings on the panel of horizontal plug-in unit:
the duration of sweep on all SWEEP TIME settings.
Model 1780A:
e. Disconnect Test Oscilloscope. SWEEP OCCURRENCE. .. .NORMAL
Model 1781A/B:
5-24. ACCESSORY PROBES. SWEEP SELECTOR .. .MAINSWEEP
Model 1782A:
a. Set:
FUNCTION ........... OFF
SWEEP TIME ......... 0.5 MSEC/CM Model 1783A:
Vertical SENSITMTY ... 0.2 VOLTS/CM TIME MARKER. ........ OFF
5-4 01526-2 |
ACEC
