Service manual

Service Manual
• one end of the Econet cable marked IN to the IN
socket of the (uppermost) MIDI expansion card under
test
• the other end of this cable to the OUT1 socket of the
(lower) known good MIDI expansion card
• one end of the Econet cable marked 0/P to the IN
socket of the (lower) known good MIDI expansion
card
• monitor to the mains supply (don't switch on yet)
• computer to the mains supply (don't switch on yet).
Note: At this stage the cable marked 0/P is only
connected at one end. You will be prompted to
connect the other end as necessary.
Run the test
1 Follow the instructions in the section entitled Preparing
to run the individual expansion card tests on page 4-
15.
2 Press the space bar to see the rest of the menu.
3 Select the MIDI Expansion option.
4 Once the test program is loaded and the first part of
the test has been run, the screen displays the
following:
MIDI Podule Test Vx.xx DEALER
PASSED Rom test
PASSED IN socket test
Set Test Switch to THRU or move cable
PRESS <SPACE BAR> TO CONTINUE
Note that during this test you can use a test box to
switch leads between sockets. If you're not using a test
box, ignore any comments about the test switch.
5 Plug the free end of the cable marked 0/P into the
THRU socket of the (uppermost) MIDI expansion card
under test.
6 Press the space bar to start the test.
A PASSED or FAILED message appears.
7 When prompted, move the cable from the THRU
socket to the OUT1 socket, then press the space bar.
A PASSED or FAILED message again appears.
8 When prompted, move the cable from the OUT1
socket to the OUT2 socket, then press the space bar.
A PASSED or FAILED message again appears.
9 A final message appears telling you whether the MIDI
expansion card has passed or failed.
You have now completed the MIDI expansion card test.
Follow the instructions in the section entitled Completing
the tests on page 4-6.
Backplane tests
The backplane should be tested if you suspect it is
faulty. Likely symptoms of this are
• all installed expansion cards fail their tests
• expansion cards fail their test only if installed in a
specific slot
• a known good expansion card fails a test, but then
passes the same test on another computer.
Remove the backplane
You must remove the backplane for testing. Note the
following:
• Make a record of the positions of any expansion cards
already fitted, so you can replace them in their correct
sockets after the test.
• Full instructions for the installation or removal of
expansion cards and of the backplane are given in
Part 3 - Disassembly and assembly.
Proceed as follows:
1 Remove the top cover of the computer.
2 Ensure that the backplane and its support bar are fitted
correctly.
3 Ensure that all expansion cards are fitted correctly.
4 If no fault was visible, remove all expansion cards from
the backplane.
5 Remove the backplane from the computer.
Test the backplane
Test the backplane PCB electrically using a suitable
continuity/isolation analyser and wire harness to suit.
Note: Due to the presence of an active device no pin on
any connector may be subjected to a voltage greater than
300mV with respect to any other pin on any other
connector.
Replace the backplane
1 Replace the backplane in the computer.
2 Replace the expansion cards removed at the start of
the test in their original sockets.
3 Replace the top cover of the computer, as described in
Part 3 - Disassembly and assembly.
Ethernet I Expansion Card
The Ethernet I expansion card test should be carried out
whenever you install, repair or replace an Ethernet I card.
Note: These instructions assume that both the expansion
card and the backplane have been correctly installed
(with the Ethernet I expansion card installed in skt 1
podule slot 0). See Part 3 - Disassembly and assembly.
Connect up the equipment
It is important to connect the equipment to the computer
in the correct order. Connect the
1 keyboard to the front panel connector
2 monochrome monitor to the Mono Video socket or the
analogue RGB monitor to the Analogue RGB socket
3 monitor to the mains supply (don't switch on yet)
4 computer to the mains supply (don't switch on yet).
Run the test
1 Ensure that the Ethernet links are set for Ethernet (
towards the front of the unit), with the Ethernet I test
feedback lead connected between the Ethernet port and
the free side of the Ethernet/Cheapernet links.
Part 4 - Fault diagnosis Issue 2, June 1991 4-17