Service manual

Service Manual
Removing cables
Note: On an R225, ignore references to cables attached
to hard or floppy drives
1 Disconnect the cables from the following plugs on the
main board:
• PL4 (floppy drive controller cable)
• PL2 (floppy drive power cable)
• PL5 (PSU power cable)
2 Remove the hard disc power cable from the rear of the
hard disc drive.
3 Disconnect the twisted pair leads for the speaker and
the green power-on LED by removing the connectors
from LK13 and LK14 on the main board.
4 Unbolt the PCB earth strap (item 42) from the drive
saddle (item 25) by removing a nut and washer (items
59 and 65). Lift the earth strap clear.
Removing the backplane
1 Remove two screws and washers (items 53 and 61)
from the backplane support bar (item 37).
2 Remove the backplane from the main board connector
SK9.
Removing the RAM and ARM
cards
1 Remove any RAM cards from the sockets SK5, 6 and
7 on the main board. (Not fitted to R225 or A540
models).
2 Remove the ARMS (PGA) PCB (item 49) from PL3 on
the main board, and remove the backplane insulation
sheet (item 40).
Note: carefully store the PCBs, ensuring that all anti-
static precautions are taken.
Removing the main PCB
1 Remove the two PCB backplate retaining screws and
washers (items 52 and 62) from the rear of the unit.
2 Carefully slide the main PCB out from the rear of the
unit.
Note: carefully store the main PCB, ensuring that all
antistatic precautions are taken.
Removing the front moulding
assembly
1 Remove the two screws (item 55) securing the front
moulding assembly (item 7) at each side.
2 Stand the unit on one side and remove from the
underside the three screws (item 56) securing the front
moulding assembly to the base metalwork (item 10).
3 Stand the unit back on its feet, grasp the front
moulding assembly at each end and use a straight,
steady pull to withdraw it half way from the front of the
unit.
4 Disconnect the amber LED cable (item 45) from the
front of the hard disc drive (item 80).
5 Completely remove the front moulding assembly.
6 For access to the indicator LEDs, locate and remove the
two self-tapping screws (item 56) at each end inside the
main front moulding and slide the sub-moulding (item
21) away from the main moulding.
Removing the floppy disc drive
1 Remove the floppy disc drive (item 22) complete with
the floppy drive bracket (item 24) by unscrewing two
screws (item 57) and plain washers (item 61) securing
the drive bracket to the drive saddle (item 25).
2 Lift the drive and bracket clear from the case.
Note: There is no floppy drive fitted to R225 models, but
the drive bracket is still present (to add rigidity to the
structure).
Removing the hard disc drive
1 Remove the SCSI hard disc drive (item 80) complete
with the hard disc bracket (item 39) by unscrewing the
two securing screws (item 57).
2 Lift the drive and bracket clear from the case.
Note: There is no hard disc fitted to R225 models
Removing the power supply unit
CAUTION: DOUBLE POLE/NEUTRAL FUSING
The PSU is fitted with a double-pole switch and
both the Live and Neutral lines are fused.
1 Turn the unit on its side and remove the four fixing
screws and washers (items 53 and 63) from the
underside of the base metalwork.
2 Stand the unit back on its feet, and slide the PSU (item
31) forward to clear the rear moulding, then lift it clear.
Note 1: When installing a PSU, the system should be
tested for satisfactory earth continuity in accordance with
BS7002/EN60950.
3-2 Issue 2, June 1991 Part 3 - Disassembly and assembly