Service manual

Service Manual
Note 2: The PSU is a service replacement only item.
DANGER:
WHEN REFITTING OR FITTING A
REPLACEMENT ASSEMBLY, CHECKS
SHOULD BE MADE FOR EARTH CONTINUITY
AS DESCRIBED-IN Appendix D - Earth continuity
testing.
Main unit assembly
Assembly is generally the reverse of the disassembly
procedures, but take care with the routing of cables and
ensure that leads are not trapped when refitting
assemblies to the main unit.
Keyboard
The computer may be fitted with either one of two
keyboards:
• Panasonic (fitted on most models)
• Keytronic (on some early models). Both keyboards
are identical on the exterior; they only differ internally,
in that they have different PCBs.
Disassembly
1 Invert the keyboard and place it on a soft, level
surface.
2 Remove the eight cross-headed screws securing the
two halves of the case and carefully lift the base
moulding away.
3 The PCB in the Keytronic keyboard is fixed to the top
moulding by six No. 6 x 0.25" screws.
The PCB in the Panasonic keyboard is fixed to the top
moulding directly by four screws, and also by means of
two metal brackets (with four screws and washers).
For the Panasonic keyboard, first remove the two
screws and washers fixing the brackets to the top
moulding, then remove the remaining screws fixing the
PCB directly to the moulding (you can leave the
brackets attached to the PCB).
For the Keytronic keyboard, remove the six screws
fixing the PCB to the top moulding.
4 Note that the reset switch cap must be removed from
the original keyboard and fitted to the replacement.
Assembly
Keyboard assembly is generally in reverse order, with the
following notes:
Slot the PCB support tray under the two fixing screws at
the end furthest from the keyboard cable, then insert the
remaining screws. Check that all keys clear the cutouts in
the top moulding before finally tightening all PCB fixing
screws.
Mouse
The mouse is a service replacement only item.
Part 3 - Disassembly and assembly Issue 2, June 1991 3-3