High-Voltage Adjustment (Sn 3001A And Below) - HP 8566B Adjustment Manual

2. High-Voltage Adjustment (SN 3001A and Below)

This procedure is for IF-Display Sections with serial number prefixes
3001A and below. The procedure for serial prefixes 3004A and above
is located immediately after this procedure.
This procedure should be performed whenever the AlAll High
Voltage Multiplier, AlVl CRT, or AlA High Voltage Regulator
Assembly is repaired or replaced.
IF-Display Section:
This procedure is intended for adjustment purposes only.
Voltages are present which, if contacted, could cause serious
personal injury. Approximately -4000 V dc can be present on
the AlA High Voltage assembly even when the ac line cord is
disconnected. Do not attempt to remove the AlA High-Voltage
Assembly from the instrument. Do not disconnect the CRT's
post-accelerator cable; the CRT can hold a + 18 kV dc charge for
several days.
If for any reason the AlA High Voltage Assembly or the
postaccelerator cable must be removed, refer to "Discharge
Procedure for High Voltage and CRT" at the end of this
adjustment procedure.
A 1OOO:l divider probe is used to measure the CRT cathode voltage.
First, the high-voltage probe is calibrated by comparing measurements
of the + 100 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 AlA HV ADJUST control. When
the CRT cathode voltage is properly adjusted, the CRT filament
voltage will be +4.45 f0.04 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 3-3 1