Re: Akai AX60 startup


"Kurt Lochner" <kurt_lochner@xxxxxxxxxxxxxxxxx> wrote in message
news:4695AF00.1B170D07@xxxxxxxxxxxxxxxxxxxx
Gareth Magennis wrote:

<wdonzelli@xxxxxxxxx> wrote in message
news:1184113618.212235.257880@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Jul 10, 4:57 am, "Gareth Magennis" <sound.serv...@xxxxxxxxxxxxx>
wrote:

It doesn't really matter really. The one you have is faulty and what
you
see is probably some random sequence of events that happens when it
doesn't
boot up. If you can hear the chorus whooshing, chances are the audio
circuits and their power supply are OK, and it is the computer that is
not
working. Might just be the 5 volt supply. Might be much worse.

It really does matter. What I am seeing seeing is a pattern that gets
stuck at various places, never completing. By knowing what the pattern
is supposed to look like, perhaps I can find out why it is getting
stuck. Perhaps something is stopping the processor clock randomly, or
maybe a data line is acting funny - I do not know. It is clearly a
problem in some sort of grey area.


And that problem will produce totally unpredictable results, the
observation
of which will tell you nothing, or mislead you completely.

If you really want to spend some time on this I suggest you get a scope
and
look at clocks and data/address lines as you try and boot the machine.
Sometimes a faulty data/address line will just not look right (it may
clamp
at intermediate levels, or just not look right when compared to others).
If
any line has a problem, the program data is effectively corrupted and the
machine will behave randomly, halt, or cycle for ever, resulting in those
patterns you are seeing. Unfortunately, there are usually several chips
all
sharing the same buss, often via buffers, so finding the fault can be
almost
impossible unless you start methodically replacing chips one by one.

Nah, that's just plain wasteful. If the power supply is working
properly (which is the first place to look for cracked solder
joints, btw), and you think there's something wrong on the buss,
simply feel around for overly warm chips. I sometimes will use
a crayon to mark the suspects out, and only change the ones that
actively melt the wax.



So you mean you methodically replace the chips one by one? That's just
plain wasteful.



As for this Akai AX-60, I recommend a little percussive tuning,
see if the power-on bootup becomes consistent, though at this
point and from what I've read so far, it's the power supply or
some connections between the boards and supply. No harm in
talking it apart for a look-see, maybe reseat the chips and
cables too..

--My Akai X-7000 acted similarly, resoldered the power supply..


Yes, you always start with the power supply, as I have mentioned twice
already.



Gareth.


.

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