2. High-Voltage Adjustment (SN 3004A and Above)
The High-Voltage Adjustment procedure does not require the removal
or discharge of the
High-Voltage Regulator or
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.
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
V dc charge
for several days if the post-accelerator cable is improperly
disconnected.
1. Remove the ac line cord from both instrument sections.
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.
3. Connect one end of a jumper wire (made of insulated wire and
two alligator clips) to the blade of the screwdriver. Connect the
other end of the jumper wire to the metal chassis of the
Section. This grounds the screwdriver.
4. Slide the screwdriver’s blade between the CRT and the sheet metal
as shown in Figure 3-15. Gently work the tip of the screwdriver
under the post-accelerator cable’s rubber shroud. Make sure
that the screwdriver’s tip touches the connection between the
postaccelerator cable and the CRT. You should hear a cracking
sound when the cable discharges.
5. Remove the cover from the
High-Voltage Regulator assembly.
6. Touch the screwdriver’s tip to the top lead of each of the 11 large
vertical capacitors on the
High-Voltage Regulator assembly.
7. The
High-Voltage Regulator and
CRT assemblies should
now be discharged.
3-46 Adjustments