HP 9020 Service Manual page 175

Assembly Access
4-75
• When storing the CRT, place it where it cannot fall or be bumped.
• The CRT envelope acts as a big capacitor when the computer is turned off. Always allow a
minute or two for the envelope to discharge before touching the anode connector.
• There is a bleeder resistor on the anode terminal. However, it is a good idea to ground the
anode before touching it. Use a screwdriver to ground it to the Aquadag of the tube, or ground
it to the chassis through a I-megohm resistor. If the screwdriver draws a fat spark, the bleeder
resistor is open.
Note
Leave the front bezel assembly in place unless its removal is required by
CRT replacement or replacement of the bezel or its glass window.
Top Cover and Rear Cover
Remove the top cover to access any assembly in the display. Remove the rear cover to access the
RFI board, graphics/digital video board, video board, CRT/yoke assembly, or fan. The top cover
must be removed to remove the rear cover.
The top cover is attached by four tab locks, two on each side (Figure 4-78). Release the locks by
pushing in with a narrow flat-blade screwdriver at a 45° angle. Release both front locks first; then
release the two rear locks. Lift the top cover off of the display.
TOP COVER
Figure 4-78. Removing Top Cover
Remove the rear cover by releasing the left side of the cover from the chassis, swinging the cover
away from the chassis, and then releasing the right side.