Tektronix 422, Instruction Manual

Page: 130 / 213

Performance Check/Calibration—Type 422 AC-DC
55. Check External Horizontal Bandwidth
a. Turn the HORIZ ATTEN control fu lly clockwise.
b. Connect the low-frequency constant-amplitude sine-
wave generator to the HORIZ IN connector through the
BNC to dual binding post adapter, 42-inch 50-ohm BNC
cable and 50-ohm BNC termination.
c. Set the constant-amplitude generator fo r six divisions
of horizontal deflection at 50 kilohertz.
d. W ithout changing the output amplitude, increase the
output frequency o f the constant-amplitude generator until
the display is reduced to 4.2 divisions ( - 3 dB point).
e. CHECK—Output frequency of generator must be 500
kilohertz or higher.
f. Disconnect all test equipment.
56. Check External Blanking
a. Connect the low-frequency sine-wave generator to the
INPUT 1 connector through the BNC to dual binding post
adapter, 42-inch BNC cable, the BNC T connector and the
50-ohm BNC termination.
b. Change the following control settings:
T IM E /D IV 10 ps
X I 0 MAG Pushed in
c. Set the sine-wave generator fo r a four-division display
(two volts positive, peak) at 50 kilohertz.
d. Adjust the LEVEL control fo r a stable display.
e. Connect the output of the BNC T connector the EXT
BLAN KING connector w ith an 18-inch BNC cable.
f. CHECK—The positive peaks o f the displayed signal
should be blanked w ith a normal INTENSITY control set­
ting (see Fig. 5-31).
g. Disconnect all test equipment.
57. Check/Adjust Calibrator Amplitude
PERFORMANCE CHECK O NLY
Parts a through g of this step are not applicable to a
performance check. Proceed to part h.
a. Connect the precision DC voltmeter from pin connec­
tor G on the Calibrator and Regulators board (see Fig.
5-32) to chassis ground.
b. Remove transistor Q775 (see Fig. 5-32) from its
socket.
c. CHECK—Meter reading; —2 volts ±10 m illivolts (w ith ­
in 0.5%).
Fig. 5-31. Typical CRT display when checking external blanking.
Q775
Fig. 5-32. Location of calibrator test points and amplitude
adjustment (Calibrator and Regulator board).
d. ADJUST—Calibrator Am plitude adjustment R780
(see Fig. 5-32) fo r exactly —2 volts.
e. Connect the precision DC voltmeter from pin connec­
tor J on the Calibrator and Regulators board (see Fig. 5-32)
to chassis ground.
f. CHECK—Meter reading: —200 m illivolts ± 3 m illivolts
(within 1.5%).
g. Disconnect the voltmeter and replace Q775.
5-36
h. Connect the 1X probe to the INPUT 1 connector.