Access ATB420 Series Service Manual page 31

Access keyboards ATB 420/421 Multi-Function Keyboard Product Specification and Service Guide
To re-assemble the matrix back into the keyboard base, hold the matrix at the back and locate the
mouse switch PCB tangs and the chassis plate into the base moulding apertures at the front of the
keyboard. Tilt the keyboard towards you and carefully ease the TACT switches under the mouse
keys and then gently lower the matrix into position. Replace the 3 screws and locate the matrix
ribbon into its connector. Check that the tactile feel of the mouse tact switches.
7.2.4 Replacement of individual key switches.
The ATB420 uses replaceable switches and has a high quality PTH (Plated Through Hole) circuit
board, which enables switches to be replaced by an operator who is trained in desoldering
techniques. The recommended procedure for replacing a switch is as follows.
Step 1
Desolder the four pins of the switch to be removed
Step 3
Push down on the centre plastic pin of the switch.
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Step 2
Ensure that all the solder is removed around
the pins and that the pins are free to move.
Step 4
Inspect the circuit board to check that the
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