HP 8568B, Performance Tests And Adjustments Manual, Page: 153 / 313

2. High-Voltage Adjustment (SN and Above)
2. High-Voltage
Adjustment (SN
and Above)
Note
This procedure is for IF-Display Sections with serial number prefixes
and above. The procedure for serial prefixes and below
is located immediately before this procedure.
Note
This procedure should be performed whenever the CRT or
High Voltage Regulator Assembly is repaired or replaced.
Reference
IF-Display Section:
A Z-Axis Amplifier
High-Voltage Regulator
V Regulator
+ 120 V, V Regulator
Description
Warning
This procedure is intended for adjustment purposes only.
Voltages are present which, if contacted, could cause serious
personal injury. Approximately -2400 V dc can be present on
the High Voltage Regulator Assembly even when the ac
line cord is disconnected. Do not attempt to remove the
High-Voltage Regulator Assembly from the instrument. Do not
disconnect the CRT’s post-accelerator cable; the CRT can hold a
+ 9500 V dc charge for several days.
If for any reason the High Voltage Assembly or the
post accelerator cable must be removed, refer to “Discharge
Procedure for High Voltage and CRT” at the end of this
adjustment procedure.
A divider probe is used to measure the CRT cathode voltage.
First, the high-voltage probe is calibrated by comparing measurements
of the + 120 V dc supply voltage with and without the probe. Any
measurement error due to the use of the high-voltage probe is
calculated into the adjustment specification of
the
CRT cathode
voltage, which is adjusted with the HV ADJUST control. When
the CRT cathode voltage is properly adjusted, the CRT filament
voltage will be
V rms measured with CRT beam at
cut-off, which is required for maximum CRT life. The filament voltage
is referenced to the high-voltage cathode and can only be measured
directly with special equipment.
Adjustments 3-39