Section V Model 120B
Paragraphs 5-23 to 5-34
5-26. The following paragraphs, 5-27 through 5-51,
describe the adjustments necessary to align Model the
120B.
5-27. LOW-VOLTAGE POWER SUPPLY
5-28. Table 5-4 lists the tolerances of the dc volt-
age outputs of the low-voltage power supply. If any
voltage is not within tolerance it is probable that the
line voltage is abnormal, a malfunction has occurred,
or the replacement of a tube or part has caused the
misadjustment. If it is confirmed that the power sup-
ply and line voltage are normal and the voltages are
not within tolerance, adjustment is then required.
5-29. -150-VOLT ADJUSTMENT. Using a dc VTVM,
adjust potentiometer R352 (figure 5-1) for -150 volts
dc.
5-30. +19-VOLT ADJUSTMENT. There is no ad-
justment for the +19-volt output; if out of tolerance a
faulty transistor or part is indicated, or afault exists
in the -150-volt power supply.
5-31. +300-VOLT ADJUSTMENT. There is no ad-
justment for the +300-volt output; if out of tolerance
a faulty tube or part is indicated, or a fault exists in
the -150-volt power supply.
5-32. +loo- AND +99-VOLT ADJUSTMENT. There
is no adjustment for these outputs; if out of tolerance
a faulty tube or part is indicated, or a fault exists in
the -150-volt power supply.
Note
If the +300 volts is dc within toler-
ance and the +I00 and/or +99 volts
dc are not within tolerance, a fault
exists in V308 or associated parts.
5-33. HIGH-VOLTAGE POWER SUPPLY.
5-34. Adjust the high-voltage power as supply follows:
Figure 5-4. Right-Side View, Side Panel Removed, Note
Location of Parts and Adjustments Adjustment of the high voltage affects
crt deflection sensitivity, intensity,
focus, and astigmatism. Checkhor-
c. Remove socket from crt base. izontal and vertical gain adjustments
following any adjustment of the high
d. Slide crt forward and out.
e. Replace reverse in order. voltage. Intensity, and focus, astig-
matism adjustments are included in
f . Energize the Model 120B and obtain free- a
running trace. the following adjustment of the high-
g. If necessary, align graticule and trace by ad- voltage power supply.
justing SCALE control.
WARNING
5-23. ADJUSTMENTS. Voltages in excess of 2,500 volts are
present in the high-voltage power
supply. Take all possible precau-
5-24. ADJUSTMENTS FOLLOWING REPAIR. tions when performing high-voltage
measurements.
5-25. Table 5-3 lists the adjustments required fol-
lowing the replacement of a tube, transistor, or a. Connect high-voltage voltmeter between terminal
diode. If a part associated with an item listed in the 17 or 18 of transformer T302 and ground.
table is replaced, check the adjustment of the listed b. Adjust potentiometer R308 (figure 5-1) for a
item. voltmeter reading of -2500 volts. |
ACEC
