HP 54520 Series Service Manual page 105

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Chapter 6: Replacing Assemblies
To remove and replace the keyboard
To remove and replace the keyboard
Use the following procedure to remove and replace the keyboard assembly. When necessary,
refer to other removal procedures.
Disconnect the power cable.
Remove the cover.
Remove the power supply.
Keyboard cable routing
Before going further, note the routing of the keyboard cable. It should be routed next to the front
panel to just under the CRT, then directly routed to the rear of the instrument where it connects to
the main assembly. It should be kept close to the main assembly for its entire length. Avoid
routing the cable between the power supply and the acquisition circuitry on the main assembly.
From the back side of the front panel, remove the four screws that, secure the
keyboard assembly to front of the cabinet.
Use the following steps to disassemble the keyboard assembly.
a Remove the knobs. They have a friction fit on the shafts.
b Remove two screws that secure the keyboard spacer to the assembly.
c Slide the keyboard spacer down until the tabs at the top are clear of the keyboard
panel.
d_ Lift the top of the spacer away from the keyboard and slide the spacer out of its
bottom mounting.
e Lift the keyboard off of the keyboard panel and keypad.
f The Keyboard label uses self-stick adhesive. If it must be removed, peel it off.
# Ifit is necessary to replace the PC board, disconnect the keyboard cable at the
keyboard.
Replace keyboard assembly by reversing this procedure. Be sure the keyboard
cable is routed properly when reassembling the instrument. (See "Keyboard Cable
Routing" above.)
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