Keithley 2520, Service Manual, Page: 94 / 137

5-4 Disassembly Model 2520 Pulsed Laser Diode Test System Service Manual
Case cover removal
Follow the steps below to remove the case cover to gain access to internal parts.
WARNING Before removing the case cover, disconnect the line cord and any test
leads from the instrument.
1. Remove handle — The handle serves as an adjustable tilt-bail. Adjust its position
by gently pulling it away from the sides of the instrument case and swinging it up
or down. To remove the handle, swing the handle below the bottom surface of the
case and back until the orientation arrows on the handles line up with the orienta-
tion arrows on the mounting ears. With the arrows lined up, pull the ends of the
handle away from the case.
2. Remove mounting ears — Remove the screw that secures each mounting ear. Pull
down and out on each mounting ear.
NOTE When re-installing the mounting ears, make sure to mount the right ear to the
right side of the chassis, and the left ear to the left side of the chassis. Each ear
is marked “RIGHT” or “LEFT” on its inside surface.
3. Remove rear bezel — To remove the rear bezel, loosen the two screws that secure
the rear bezel to the chassis, then pull the bezel away from the case.
4. Remove bottom screws — Remove the six screws that secure the case to the chas-
sis. They are located on the bottom of the case.
5. Remove chassis — To remove the case, grasp the front bezel of the instrument,
and carefully slide the chassis forward. Slide the chassis out of the metal case.
Motherboard removal
Perform the following steps to remove the motherboard. This procedure assumes that the
case cover is already removed.
1. Remove the IEEE-488, DIGITAL I/O, RS-232, and TESTHEAD CONN 1 fasten-
ers. The IEEE-488, DIGITAL I/O, RS-232, and TESTHEAD CONN 1 connectors
each have two screws that secure the connectors to the rear panel. Remove these
screws.
2. Remove the motherboard mounting screws. Remove the five mounting screws that
secure the motherboard to the chassis.