Service manual
Also check that the main PCB links are set correctly.
See Appendix F - Main PCB links, plugs & sockets for
LK18, LK19 and LK21.
Try to format a new floppy disc and retest the drive by
attempting to read the original disc on another machine.
Note that if this fails the disc may be corrupted.
As a final measure, try substituting a known working
floppy disc drive. Depending on the outcome of this test,
return either the main PCB or the drive to an Authorised
Acorn CSW for repair.
Real time test
The screen will clear and the following menu will be
displayed:
TIME TEST VX.XX DEALER
1) CHECK THE DATE AND TIME
2) SET THE DATE AND TIME
3) CHECK THEN SET THE DATE AND TIME
Please select the required option ?
The normal procedure is to select option 1. If you want to
reset the time or date you would select 2 or 3. For
example, you can:
• type 1 to check the date and time
• check that the time is correct and the seconds are
incrementing correctly.
Then either press F5 (if correct) or F8 (if not correct),
and press the space bar to continue.
Action if real time test falls
If the test fails, refer to the section entitled Action if main
PCB fails on page 1-3.
Audio tests
Note that the audio tests are subjective tests and that
you should be familiar with the correct sounds before
running the tests.
Speaker tests
The screen clears and the following menu is displayed:
SOUND TEST VX.XX DEALER
Running Loudspeaker Test
Listen and check sound quality
Stereo Output Channel
Flashing arrow heads (««) will then point alternately left
and right depending on the stereo channel being used.
The test consists of a repeating sequence of 8 musical
notes.
1 Listen to the sequence of notes.
2 Check for any deviation from the known good sound,
and ensure that a clean sound is being emitted from
both channels.
3 Listen for any interference or background hissing from
the speaker.
Press F5 if correct, or F8 if not correct, to continue. You
cannot press a function key until at least one cycle of
each sound channel is complete. If the test fails, refer to
the following section entitled Action if audio tests fail.
Headphone tests
The headphone test is similar to the speaker test except
that the sound is sent through the headphones. The
same checks that are used for the loudspeaker test
should be undertaken. The first four notes are played in
one headphone and the next four notes in the other
headphone.
The screen will then clear and the sound test results will
be displayed. If the test fails, refer to the following
section entitled Action if audio tests fail.
Action if audio tests fail
If it appears that the speaker alone is at fault, check the
speaker connections. Ensure that the cable connecting
the speaker to the PCB is in place. Also check the
solder joints on the speaker tags and the two crimps in
the shell. Repair any bad joints and try the tests again.
For details of how to remove the speaker, refer to Part 2
-Disassembly and assembly.
If the headphones alone appear at fault, substitute a
known working pair of headphones and retest.
Also check that the CMOS RAM configuration has not
been set to mute the speaker and that the audio volume
is set to an appropriate value.
If these actions fail to restore the audio system or the
audio system is distorted or corrupted in some way, you
must remove the main PCB and return it to an Acorn
Authorised CSW.
Video tests
The display tests are subjective tests and you should be
familiar with the correct screen displays before running
these tests and make a note of any failures.
The screen will clear and the following will be displayed:
VIDEO TEST VX.XX DEALER
Running Standard Colour Tests
PRESS <SPACE BAR> to continue.
These tests consist of a series of screen displays. You
proceed through the tests at your own pace. When you
press the space bar the screen test will commence.
1-12 Issue 1, November 1991 Part 1- Fault diagnosis and repair