HP 8568B, Performance Tests And Adjustments Manual, Page: 157 / 313

2. High-Voltage Adjustment (SN and Above)
16. With the front-panel INTENSITY control fully counter clockwise,
wait approximately 10 minutes to allow the high-voltage supply to
stabilize and the CRT to normalize. This
turn-on will extend
CRT life expectancy, particularly if a new CRT has just been
installed.
17. Readjust HV ADJ for a DVM indication equal to
the
voltage determined in step 15.
18. If a new CRT has just been installed do
the
following:
a. Set the front-panel INTENSITY control so the CRT trace is
barely visible.
b. Wait an additional 30 minutes for the CRT to normalize.
c. Readjust HV ADJ for a DVM indication equal to the
voltage determined in step 15.
19. Set the LINE switch to STANDBY. Remove the ac line cord from
each instrument section.
20. Wait at least one minute for
the
MAINS power-on indicator
(red LED) to go out completely before proceeding.
21. Disconnect the high-voltage probe from
22. Replace the cover on the High-Voltage Regulator Assembly.
23. The High-Voltage adjustments are now completed. If
the
assembly has been repaired or replaced, perform adjustment
procedure 3, “Preliminary Display Adjustment (SN
and
Above)“, and then adjustment procedure 4, “Final Display
Adjustments (SN
and Above)“. If the assembly
functions properly and does not require compensation, proceed
directly to adjustment procedure 4, “Final Display Adjustments
(SN
and Above)“.
Discharge Procedure
The High-Voltage Adjustment procedure does not require the removal
for High Voltage and
or discharge of the Al High-Voltage Regulator or CRT
CRT assemblies. However, if for any reason the High Voltage
Regulator Assembly,
the
CRT, or the CRT post-accelerator cable must
be removed, perform the following procedure to ensure proper safety.
Warning
This procedure should be performed by qualified personnel 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. The CRT can hold a + 9500 V dc charge
for several days if the post-accelerator cable is improperly
disconnected.
1. Remove the ac line cord from both instrument sections.
Warning
With the ac power cords disconnected, voltages can still be
present which, if contacted, could cause serious personal injury.
2. Obtain an electrician’s screwdriver which has a thin blade at least
eight inches long. The handle of the screwdriver must be made of
an
insulating material.
Adjustments 3-43