Keybutton; Type A Switch Module - IBM 3277 Troubleshooting Manual

5.3.5.5 Keybutton
A keybutton should be replaced when it deteriorates in
appearance or when it fails to remain attached to the key
stem. Buttons are removed by sliding the key top puller tool
over the key top and pulling straight up.
5.3.5.6 Type A Switch Module
Steps 1-3 must
be
performed in the order listed before
removing the switch module.
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. Switch Module Removal (Except Spacebar Switch
Module):
1. Record locations of keybuttons in area of switch
module (PN 5995542) being replaced. Remove
keybutton from faulty module (and from as many
others as needed to provide work space).
2. Take the two small, flat, pointed tools from box
containing new module, and slip one down the
inside face of each D bracket (retainer) to force
brackets away from locking channels on plastic
case of old module (Diagram 5-2).
3. With flat tools in this position, grip shouldered
portion of switch module plunger with pliers, and
pull switch module straight out.
CAUTION
In the next step, do not apply the soldering iron
for longer than necessary to flo·"" the solder.
Diagram 5-2. Switch Module Removal (Type A)
4. The black plastic lead frame package is left behind
when the plunger assembly is removed. Usinp
solderwick (PN 5151439), unsolder and remOVE
excess solder from the fou r terminal pads on
printed circuit board (Diagram 5-3).
Remove lead
frame package from printed circuit board (Dia-
gram 5-4).
15-Watt Soldering Iron
Lead Frame Terminal Pads
Diagram 5-3. U nsoldering Lead Frame Terminals (Type A)
lead Frame
Package
Diagram 5-4. Lead Frame Removal (Type A)
Checks, Adjustments, and Removals 5-15