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2. High-Voltage Adjustment (SN 3004A and Above)
2. High-Voltage
Adjustment (SN
3004A and Above)
Note
This procedure is for IF-Display Sections with serial number prefixes
3004A
and above. The procedure for serial prefixes
3001A
and below
is located immediately before this procedure.
Note
This procedure should be performed whenever the
AlVl
CRT or
AlA
High Voltage Regulator Assembly is repaired or replaced.
Reference
IF-Display Section:
A
lA2
Z-Axis Amplifier
AlA
High-Voltage Regulator
AlA
&15
V Regulator
AlA
+ 120 V,
+5.2
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
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 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
+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.
Adjustments 3-39