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Model 8901B
Service
8-WAY
0
R
IENTATI ON
OF KEYCAP
M IN I AT U R E
C
0
NTACT
PADS
P.C.
BOARD
~
~~
Figure 8C-1. Ront-Panel Pushbutton
Switch Assembly
Switch
Replacement
The front-panel switches have a very high cycle life. However, if one becomes faulty and needs
replacement, follow the procedure outlined below:
1. Remove the pushbutton key cap. You will have to pull hard. Use your free hand
to
hold the board
2. Lower the front panel (refer to the F'ront-Panel Disassembly Procedure).
3. Remove the switch by chipping away the melted plastic tabs at the circuit of the keyboard which
hold the switch in place.
4. To assure long life and reliable electrical performance, the circuit board contact traces (which are
found underneath the switch) should be clean and free of surface imperfections. Clean the switch
contact pads before installing a new switch. Make sure the
LEDs
are not tilted and that there is
no excess solder around the leads.
5.
For reliable operation, any method of assembly must assure that the switch is mounted tightly
against the pc board. To facilitate the heat staking operation, specially molded support anvils
(HP
5040-6881) can be ordered.
down as you pull.
Disassembly Procedures
8C-3
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