Location Of High Voltage Adjustments - HP 8568B Performance Tests And Adjustments Manual

4. Set the LINE switch to ON. Set the front-panel INTENSITY
control fully counterclockwise (CRT beam at cut-off) to prevent
possible damage to the CRT.
5. Note the DVM indication at AlA7TP3.
6. Connect
probe to AlA7TP3.
7. Note the DVM indication.
8. Divide the DVM indication in step 7 by the DVM indication in
step 5. This gives the calibration factor needed to compensate for
high-voltage probe error.
9. Disconnect the high-voltage probe from AlA7TP3. Set the
LINE switch to STANDBY. Remove the ac line cord from both
instrument sections.
Warning
The MAINS power-on indicator AlASDSl (red LED) should
be completely off before proceeding with this procedure. See
Figure 3-13 The indicator will remain lit for several seconds after
the ac line cord has been removed, and will go out slowly (the
light becomes dimmer until it is completely out).
Warning
With the protective cover removed in the following step, do not
place hands near the AlA High-Voltage assembly. High voltage
(approximately -2400 V dc) can present even when the ac line
cord is disconnected.
10. Wait at least one minute for capacitors to discharge to a safe
level.
2. High-Voltage Adjustment (SN 3004A and Above)
V O L T A G E
R E G U L A T O R
Figure 3-13. Location of High Voltage Adjustments
the
high-voltage probe to the DVM, and connect the
DVM Indication:
DVM Indication:
Calibration Factor:
Adjustments 3-41