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return spring seats on raised boss on bottom of
mounting frame.
Once new module is in place, check that plunger
moves freely, that top su rface of modu Ie does not
extend above other modules, and that D brackets on
mounting frame have locked module firmly in place.
3. Reassemble key buttons on switch modules. Check
that correct keybuttons are returned to correct
module positions.
5.3.5.9 Type B Module
Steps 1-3 must
be
performed in the order listed before
removing the module.
Cleanliness is important when
working
on
the keyboard. Any particle between the key
module flyplate and the printed circuit board is a potential
problem.
Before keyboard disassembly, prepare a smooth,
clean work area by wiping contamination away with a
lint-free cloth dampened with isopropyl alcohol. Gently
tap, brush, and shake the keyboard assembly to remove
most loose particles that could get into the PC board and
flyplate area during disassembly and reassembly.
1. Disconnect keyboard from display station. (See para·
graph 5.3.5.1.)
2. Remove keyboard top cover. (See paragraph 5.3.5.2.)
3. Remove keyboard assembly from bottom pan. (See
paragraph 5.3.5.3.)
A.
Module Removal
(Including Spacebar Module):
5-18
Note:
See paragraph 5.3.5.10 for spacebar removal if
spacebar module is to be replaced.
1. Ensure that all small particles that might contam-
inate the keyboard assembly are removed from the
work area.
2. Record locations of keybuttons in area of module
that is being replaced. Remove key button from
faulty module and from as many others as may
be
required to provide enough work space.
'
3. Place keyboard assembly upside down in the
cleaned area, and loosen the screws holding base
plate and circuit board to the all-keys assembly
(Diagram 5·9). Do not remove the holding screws
at this time.
4. Place keyboard assembly right side up, and slide
one corner off the work surface edge to expose
one holding screw. With fingers, remove hblding
screw from bottom.
5. Carefully rotate keyboard assembly and remove
remaining holding screws, one at a time. Keep the
all-keys assembly and PC board together.
Diagram 5-9. Screw Loosening (Type B)
6. Lift the all-keys assembly from the circuit board,
and place the assembly right side up (keybuttons
up) in the clean area. Handle the all·keys assembly
by the sides (Diagram 5-10). Be careful not to
depress any keys while removing assembly, since a
flyplate could detach.
Circuit Board and Electronics Assembly
Diagram 5·10. Keyboard Assembly Separation (Type B)
Note:
Replace the key module if the flyplate
comes off. Do not attempt to repair the module.
Repaired modules can cause intermittent failures.
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