Model 122A/AR Section V
Paragraphs 5-26 to 5-34
BINPUT ............... Shorted
e. Adjust the SCALE potentiometer on the front
panel to align a finely-focused horizontal trace with B VERTSENSITIVITY VERNIER * - - CCW
the horizontal lines of the graticule. Repeat this ad-
b, Adjust spot to center of screen with B VERTI-
) justment whenever necessary due to changes in the
CAL POSITION control.
location of the instrument or the influence of fields
generated by nearby electrical equipment. c. Turn B VERT SENSITIVITY VERNIER fully
clockwise and readjust spot to center with B BAL ad-
5-26. TRIGGER GENERATOR
justing screw.
5-27. The Trigger Generator circuit must be properly
d. Repeat this sequence until there is no displace-
adjusted before the Vertical and Horizontal Amplifiers
ment of spot as VERNIER is rotated.
can be adjusted. Also, these Amplifiers must be prop-
erly adjusted before the Sawtooth Generator can be ad- e. Set B VERTICAL POSITIONcontrol to its center
justed. The Trigger Generator circuit is adjusted as (12 o'clock). Spot should now be on screen, near
follows. center.
5-28. STABILITY ADJUSTMENT. A vacumtube volt- 5-32. CHANNEL A BALANCE ADJUSTMENT. A
meter/ohmmeter (such as hp Model 410B) andasmall small screwdriver is required for this adjustment.
screwdriver are required for this adjustment.
a. Set the Model 122A/AR controls:
VERT PRESENTATION * * * - + .A a. Set the Model 122A/AR controls:
- * - * * * *
A VERT SENSITIVITY OFF A VERT SENSITIVITY * AC, 0.01 VOLTS/CM
- * - *
B VERT SENSITIVITY * - - OFF HORIZ SENSITIVITY - * - + io VOLTS/CM
AINPUT ............... Shorted
SWEEPTIME - - * - - * 5 MILLISEC/CM
SYNC. ................... INT A VERT SENSITIVITY VERNIER * .fully CCW
TRIGGER LEVEL. fullyccw, but not onAUTO
b. Adjust spot to center of screen with A VERTI-
VERT PRESENTATION * - * - - A or B
CAL POSITION control.
b. Connect the vtvm (-100 v dc range) to pin 8 of
c. Turn A VERT SENSITIVITY VERNIERcontrol
V203. Slowly rotate Stability control R228 (see Figure
---. fully clockwise and readjust spot to center withA BAL
5-2) ccw until the sweep starts free-running, then
adjusting screw.
back control off until it just stops.
d. Repeat this sequence until there is no displace-
c. Take voltage reading (which should beapproxi-
ment of spot as VERNIER is rotated.
mately - 78 volts). Adjust R228for areading 3 volts
more positive than the last reading. e. Set A VERTICAL POSITIONcontrol to its center
) (12 o'clock). Spot should now be on screen, near
5-29. EXTERNAL TRIGGER SENSITIVITY
center.
ADJUSTMENT. A wide range oscillator (such as hp
Model ZOOCD), a test oscilloscope, anda small screw- 5-33. CHANNEL B GAIN ADJUSTMENT. A Voltmeter
driver are required for this adjustment. Calibrator (suchas hpModel738B) anda small screw-
driver are required for this adjustment.
a. Set the Model 122A/AR controls:
SYNC .................. .EXT
a. Set the Model 122A/AR controls:
TRIGGERLEVEL - * * * - AUTO
VERT PRESENTATION- - * * * + -B
DC/AC.. ................. DC
B VERT SENSITIVITY AC, 0. OlVOLTS/CM
VERT PRESENTATION ........ A or B
B VERT SENSITIVITY VERNIER *. - * * CAL
Trigger Sens R247 - - * - * * fully ccw
b. Connect a 250 kHz sine-wave of 0.7 v rms to b. Connect 100 millivolt peak-to-peak signal from
the SYNC external input terminals, and observe the the Voltmeter Calibrator into channel B input terminals.
square wave by clipping the test oscilloscope probe
c. Set GAINadjustment screw of ChannelB to give
over the body of R204 (V201A plate resistor).
exactly 10 centimeters of deflection.
c. Increase Trigger Sens control R247 (see Fig-
d. Check this setting at 127 (or 254) and 103 (or
ure 5-2) until stable triggers are obtained. Check
206) volts line input. Gain should be within 3% at all
trigger sensitivity from 50 Hz to 250 kHz. Stable
line voltages. If not, check power supplies andverti-
triggering should be obtainedwith less than 0.7 v rms
cal amplifier tubes.
over this range.
d. Remove the test set-up and check the rate when 5-34. CHANNEL A GAIN ADJUSTMENT. A Volt-
the TRIGGER LEVEL control is in the AUTO position meter Calibrator (such as hp Model 738B) anda small
(should be approximately 120 f 50Hz). screwdriver are required for this adjustment.
5-30. VERTICAL AMPLIFIERS. a. Set the Model 122A/AR controls:
VERT PRESENTATION ' . ' * . 'A
5-31. CHANNEL B BALANCE ADJUSTMENT. A
A VERT SENSITIVITY * * AC, 0.01 VOLTS/CM
small screwdriver is required for this adjustment.
A VERT SENSITIVITY VERNIER * * * - CAL
a. Set the Model 122A/AR controls: b. Connect 100 millivolt peak-to-peak signal from
VERT PRESENTATION * - * * * - - B the Voltmeter Calibrator into channel A input termi-
B VERT SENSITIVITY - AC, 0.01 VOLTS/CM nals, and repeat the procedure outlined in Paragraph
HORIZ SENSITIVITY * - - * io VOLTS/CM 5-33, adjusting channel A GAIN.
00081-4 5-5 |
ACEC
HEWLETT-PACKARD
