Key Modules - IBM 3279 2A Maintenance Information

3279 MIM
4.11.6 Key Modules
WamiDg: The work area must be clean during work
on the keyboard. Any particle between the key
module f1yplate
aod
the prioted circuit is
a
potential
problem.
4.11.6.1 Removal
Note: see section 4.11.7
if
the spacebar module is
to be exchanged.
. 1. Disconnect the keyboard from the display
station (see section 4.11.1).
2. Remove the keyboard top cover (see section
4.11.2).
3. Remove the keybutton from the module to be
exchanged (see section 4.11.5).
4. Remove the keyboard assembly from the base
(see section 4.11.3).
5. Invert the keyboard assembly, and place it on
the base using the locating pins on the left and
right sides.
6. Remove the screws that hold the bottom cover
and circuit board to the keyboard assembly.
7. Lift the circuit board and bottom cover from
the keyboard assembly, and place them in a
clean area. The part that remains on the base
is known as the all-keys assembly.
Note: Exchange the key module if a flyplate
comes off Do not attempt to repair the
module. Repaired modules can cause
intermittent failures.
8. Handle the all-keys assembly by the sides and
take care not to press any keys. Turn it the
correct way up onto the base, locating it on the
pins
9. Press down on the key module until it is
relegsed from the holding plate.
10. Handle the all-keys assembly by the sides and
take care not to press any keys. Invert it onto
the base, locating it on the pins
I I . Remove the module.
Chapter 4. Removal and Replacement Procedures 4-12
4.11.6.2 Repiacement
I. Ensure that the alignment tab and the angled
keystem are in the same position as those of the
other modules in the all-keys assembly.
2. Install the new module by pressing the key
module into the holding pIate by hand.
3. Clean the printed circuit board by carefully
wiping it with a lint-free cloth moistened with
isopropyl alcohol. Inspect every key module
fly-plate for any foreign matter, and carefully
clean if needed .
4. Align the holding screw holes through the
bottom cover, circuit
board,
insulator, and top
insulator (if used). Lower the circuit board and
bottom cover onto the all-keys assembly.
Secuse the circuit board· to the all-keys assembly
with the holding screws.
5. Reinstall the keyboard assembly on the base,
maintaining its original alignment.
6. Reinstall the keybutton in the correct location.
If you have removed the spacebar, see section
4.11.7.2.
7. Reinstall the keyboard cable connector and
clicker cable to the logic card. Reinstall the
keyboard top cover, and reconnect the keyboard
to the display if it was removed.
8. Use Test Mode 2 to check for correct operation
of the keyboard.