175A - HP Archive

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