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Note:
If the switch mounting frame becomes
distorted during removal of the old module, form
it back to its normal position. This can
be
done by
squeezing the 0 brackets together until they will
seat firmly against the sides of the new module
housing.
B.
Switch Module Replacement:
Do not disassemble
replacement module.
Lead frame and plunger
assemblies are matched during manufacture. Proceed
as follows:
1. Check that return spring is firmly seated on spring
boss on bottom of plunger of new switch module
(Diagram 5-5). If it is not, invert switch module so
that lead frame terminals are up. Place spring on
boss. Compress and rotate spring until last coil
expands around boss. When properly seated, spring
should be parallel to long axis of switch module.
Note:
When the plunger return spring is in place,
check the lead frame terminals to see that they are
not bent and that they are parallel to the long axis
of the switch module.
Lead Frame
Terminals
I~Spring
I
, /
I(
I I
I
)
Plunger
Return
Spring
Boss
Diagram 5·5. Switch Plunger Return Spring POSitioning (Type A)
5-16
2. Insert module into keyboard switch mounting
frame, with orientation arrow on top of module
pointed in the same direction as arrows on other
modules (Diagram 5-6). As module is inserted, be
sure plunger return spring seats on raised boss on
bottom of mounting frame and that the four
terminals extend through holes in printed-circuit
board.
Diagram 5-6. Switch Module Orientation (Type A)
Once new module is in place, check for the
following conditions:
• Plunger moves freely.
• Top surface of module is even with those of
other modules.
• 0 brackets on mounting frame lock module
firmly in place.
Note:
Should it be necessary to remove the new
module to correct any of these conditions,
be
careful not to mar any portion of the plunger,
since operation of the module and/or retention
of the keybutton would be affected.
CAUTION
In the next step, do not apply soldering iron for
longer than necessary to flow the solder.
3. Solder terminals of lead frame. Use a minimum
amount of solder.
4. Reassemble key buttons on switch modules. Check
to see that correct keybuttons are returned to
correct module positions.
5. Install the assembly on the bottom pan, replace
keyboard top cover, and reconnect keyboard to
display station.
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