High-Voltage Adjustment (Sn 3004A And Above) - HP 8568B Performance Tests And Adjustments Manual

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2. High-Voltage
Adjustment (SN
Note
Note
Reference
Description
Warning

2. High-Voltage Adjustment (SN 3004A and Above)

This procedure is for IF-Display Sections with serial number prefixes
is located immediately before this procedure.
This procedure should be performed whenever the AlVl CRT or
IF-Display Section:
A lA2 Z-Axis Amplifier
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 AlA High Voltage Regulator Assembly even when the ac
line cord is disconnected. Do not attempt to remove the AlA
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 AlA 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 1OOO:l 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
voltage, which is adjusted with the AlA HV ADJUST control. When
the CRT cathode voltage is properly adjusted, the CRT filament
voltage will be +6.00 kO.05 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.
the
CRT cathode
Adjustments 3-39

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