Service manual

Part 2 - Disassembly and assembly
DANGER:
BEFORE REMOVING THE TOP COVER, ENSURE THAT
THE COMPUTER SYSTEM HAS BEEN SWITCHED OFF
AND THE MAINS PLUG REMOVED FROM THE SUPPLY.
REMOVING THE TOP COVER GIVES ACCESS TO THE
POWER SUPPLY. ALTHOUGH THE POWER SUPPLY IS
DESIGNED TO COMPLY WITH BS5850 CLASS 1, YOU
MUST STILL TAKE CARE TO ENSURE THAT NO METAL
OBJECTS FALL (OR ARE PUT) INTO THE POWER
SUPPLY UNIT THROUGH THE VENTILATION HOLES.
NOTE:
STRINGENT ANTI-STATIC PRECAUTIONS MUST BE
TAKEN ONCE YOU HAVE REMOVED THE TOP COVER.
Introduction
This chapter tells you how to break down a standard
A5000 computer into its serviceable modules, in order to
carry out basic checks and replace modules found to be
faulty.
It is recommended that you remove modules in the order
given in this chapter, to ensure, for instance, that no
cables are left connected to the particular item you wish
to remove.
The main unit houses the following:
• Backplane*
• Main PCB
• 3.5" floppy disc drive
• Hard disc drive*
• Speaker
• Power supply unit (PSU).
*Hard disc drive models only
The keyboard, mouse and monitor are separate units.
See the appropriate third-party service information for
the monitor. The mouse is a service replacement only
item. This chapter makes reference (when it gives item
numbers) to the final assembly drawing (part number
0092,100/A) which you will find at the back of this manual.
Also see Appendix G - Final assembly parts list for a list
of part numbers.
Removing the top cover
1 Shutdown the computer using one of the following two
methods:
• press F12 and type SHUTDOWN (then press Return)
• select Shutdown form the Task Manager menu
This shuts the computer down correctly and parks the
hard disc, if a hard disc drive is fitted.
2 Switch off and disconnect the computer from the
mains supply and then disconnect all peripherals,
including the keyboard.
3 Place the main unit on a work surface with a clean, soft
covering and turn it over so that it rests on its top cover.
4 Remove the six fixing screws (item 46) on the
underside of the main unit.
5 Rest the main unit on its base again and slide the lid (
item 24) backwards to the rear of the unit. Remove
the lid completely.
6 Some models of the A5000 have an EMC case shield (
item 29) which fits over the case. To remove this
shield, unscrew the five fixing screws on the right hand
side of the unit, as seen from the rear. The shield has
interleaved tabs which fit into the edges of the case.
Slide the shield off the main unit carefully; there is a
hole on the top to help you slide the shield off by
inserting a screwdriver.
Part 2 - Disassembly and assembly Issue 1, November 1991 2-1