Front Panel Repair Procedure - HP 8340B Manual

Front Panel
Repair Procedures
FRONT PANEL DISASSEMBLY
Figure G-4 illustrates the following procedure.
1.
Disconnect the AC power
line cord.
2.
Remove the instrument top cover.
3.
Remove the
vinyl trim
from the top, front edge of the instrument (pry
a
corner loose and gently
peel the trim from the bezel).
4.
Remove
all
five screws under
the trim.
NOTE: The
length of these five
screws
is important (see
REPLACEABLE PARTS).
Longer screws
protrude through the display casting and can damage the display driver assembly.
5.
Remove either front foot
(instructions are on the foot) to release the information cards tray, and
remove the
tray.
6.
Remove three of the five
screws
on the lower, front
frame edge
(see Figure G-4), and loosen
a
fourth,
if
necessary.
NOTE:
The loosened
screw centers the RF connector
in the front panel opening. Be sure
the
con¬
nector is
recentered and secured during front panel reassembly.
7.
Gently pry the
front
panel and display
assembly from the frame. You may have to apply pressure
from behind, against the display assembly.
8.
If
you intend to remove the entire front panel,
you
must disconnect the five coaxial cables that
connect the front panel
BNC connectors
to the motherboard
8MB
connectors, and the two 50-
wire
ribbon
cables.
If
you intend to only troubleshoot the display
and/or keyboard assemblies, you must
disconnect
only the ribbon cable attached to the display assembly.
9.
Separate
the keyboard assembly from
the display assembly by removing the three screws
between the panel
castings.
10.
To
troubleshoot the keyboard, reconnect the ribbon cables and attach the display to the top of the
front casting for support.
11.
To troubleshoot the display, configure the display assemblies in the service position (Figure G-6),
reconnect the
ribbon cables, lay the display assembly on the reinstalled
top cover, and attach the
keyboard to the front panel for support.
G-16
Front Panel Repair Procedures
HP 8340B/41B