2 Aug
2006
2 Aug
'06
3:40 p.m.
--- Tony Duell <ard at p850ug1.demon.co.uk> wrote:
r
> Ok, here's the full story :
>
>
> I have had my Amiga 600 since 2001 and have
> added a few bits over the years:
>
> - 2.5" 4GB harddrive (I can't remember the
> make and model at the moment)
>
> - 1MB RAM (in trapdoor underneath)
>
>
> I also have a 4MB PCMCIA RAM card which is
> rarely used, and 2 external floppy drives
> (one doesn't work), with only 1 connected up.
> I haven't upgraded any of the kickstart or
> ROM chips, they are the same as when I bought it
.
I run WB2.05 (and am happy with it) with
kickstart 37.300
I don't know the board revision number off-hand
but I can find out if required.
My harddrive used to power down (powersave?)
after not being used for say 20/30 mins and
happily power-up again whenever I tried to
access the drive (via WB or via AMOS BASIC).
However, around April/May this year the drive
started to randomly power down and then,
usually, almost instantly power back up again
but WB nor AMOS could access the HD. Any
attempt to do so would freeze WB or AMOS.
My first comment is that this set-up worked
correctly for almost 5 years.
This means the set-up is capable of working, and
that the fact that it
now doesn't work means something has failed (rathe than, say, an
incompatability, or a marginally-rated PSU, or...)
to
I figured (as you would) that my harddrive
Actually, I might not. My first reaction would be stick a voltmeter on
the power lines.
errr... no voltimeter here, nor do i have a clue
where to buy one from (or how to use one).
[...]
ms
I popped along to www.amiga.org and posted
my problem up there and peeps then suggested
it might be a flaky PSU. I got myself an
A500 "heavy brick" model (AFAIK it's compatible
Again, since the original PSU worked for a long
time, it would appear it
was adequate. I don't like changing parts of syste that have worked
without a good reason.
I still have the old A600 PSU, I usually keep
faulty/suspected faulty parts for spare parts.
> and gives more power if required) by chance
> (I was planning to get another A600 PSU)
> from www.amigadeals.co.uk
>
> Everything appeared to be fixed. However, my
> A600 was running hotter than normal. I have
> always put a plastic pen above the air vent
> bit at the top of the machine (by the F1-F4 keys
)
an
y
d it used to always be cold. With this
new PSU it was warm and the underside of the
Amiga 600 was hotter than normal.
I posted my concerns to either Amiga.org or
CAR and then someone suggested that it might
be a faulty resistor. He claimed that the
I doubt it very much. If it's the resistor that's
getting too hot, then
it's dissipating too much power. In a constant
voltage set-up (that would
be the most likely), it would have to fall
significantly in value for this
to haeppen. Which is not likely. I suppose a fault resistor could upset
the biasing on some other component, and thus caus
e
that to pass too much
current, but from my memory of the A500 circuit, I
can't think of any
obvious candidate.
Ahem, it's an A600 I own ;)
Have you tried running the machine with the cover
off to see what is
getting hot? It might be something as simple as a
leaking decoupling
capacitor.
I was planning too, but I had concerns about
being electricuted (spelling?) as I had never
done that before, and also becuase of the
recent hot weather - I have no patience in
hot weather and feared running it in the
extreme heat would only cause more damage.
What would the "leaking decoupling capacitor"
look like, if that was the cause?
Which is the capacitor? Anyone know?
[...]
I wish!. I'd love an Model 16, but they're not at
all common in the UK,
and would not be cheap (or easy) to ship from the
States. In a moment of
madness I did get a CoCo3 sent from the States
(brand new machine, some
16 years ago), but that was just the
keyboard/processor unit, not a CRT
monitor and drives too.
-tony
Probably best you didn't get the 16, as it's
inferior to the 12!
The 12 was actually made later than the 16
and supports various modes making it
compatible with 16 and 4 (?) software
(and hardware?). Infact I think the Model 12
was the best of the bunch.
Regards,
Andrew B
aliensrcooluk at yahoo.co.uk
> My second computer was a TRS-80 Model 1 (my
first,
> FWIW, was an MK14, yes
> I still have both). I now have a Model 3 and
Model
4, and
several CoCos.
And schematics, etc for all of them.
-tony
Cool :) Were you ever tempted with the Model
16 or 12? 
3 Aug
3 Aug
2:32 a.m.
aliensrcooluk at yahoo.co.uk wrote:
Get yourself down to a Maplin store - whilst Maplin's don't half sell some
junk these days, they always seemed to have good deals on multimeters. The one
on www.maplin.co.uk, code GW24B, is 30 pounds and does everything you could
expect of it, plus a few 'features' like capacitance and frequency measurement.
electrocuted - close! :-)
There shouldn't be any mains voltage inside the Amiga - it's all low-voltage
DC. No problem there (just don't use anything metallic whilst the machine's on
obviously, in case you accidentally short something out!)
You can touch the tops of chips to see if any of them are getting over-warm
(that's all relative though as different bits will run hotter than others by
design; if it's too hot to keep your finger on for any length of time then
that's often a good sign that something's wrong!)
Oh, have you checked the hard disk cable, connector on the A600 board, and the
connector on the hard disk itself? Just a thought. Check for damage, bad
connections etc. - I've know hard drives do strange things when the connection
isn't quite behaving itself.
Worth taking the main PCB out of the machine itself too, just to make sure
that a particle of something metallic hasn't worked its way underneath and is
shorting out something that it shouldn't be. Those sorts of 'mechanical'
checks tend to be easy to do before reaching for any test equipment.
cheers
Jules
--
A. Because it destroys the natural flow of conversation.
Q. What's wrong with top posting ?
stick a
voltmeter on the power lines.
errr... no voltimeter here, nor do i have a clue
where to buy one from (or how to use one). Have you tried
running the machine with the cover off to see what is
getting hot? It might be something as simple as a leaking decoupling
capacitor.
I was planning too, but I had concerns about
being electricuted (spelling?) as I had never 
3:02 p.m.
I figured (as you would) that my harddrive
Actually, I might not. My first reaction would be stick a voltmeter on
the power lines.
errr... no voltimeter here, nor do i have a clue
where to buy one from (or how to use one). e
Yes, I know. I don't have an A600 circuit diagram. I am assuming the
basic design, at least around the PSU input circuitry, is going to be
similar.
that to pass too much
current, but from my memory of the A500 circuit, I
can't think of any
obvious candidate.
Ahem, it's an A600 I own ;) Have you tried running the machine with the
cover
off to see what is
getting hot? It might be something as simple as a
leaking decoupling
capacitor.
I was planning too, but I had concerns about
being electricuted (spelling?) as I had never done that before, and also becuase of the
recent hot weather - I have no patience in
hot weather and feared running it in the
extreme heat would only cause more damage.
Yes, the heat doesn't encourage one to hack :-(
What would the "leaking decoupling capacitor"
look like, if that was the cause?
It will look like any other capacitor. The 'leak' is an internal
electrical leak (a sort of weak short circuit). You'd have to find it by
doing electrical tests.
Which is the capacitor? Anyone know?
The thing about decoupling capacitors is that they provide a local source
of energy for the various chips, thus avoiding the voltage drop due to
the resistance, and more particularly the inductance, of the supply
connections. Therefore there is one (or more) next to each chip. And
there's no way _anyone_ can tell you which has failed without doing more
tests.
-tony
Probably best you didn't get the 16, as it's
inferior to the 12!
Come again? The 16 has a 68000 processor board (as well as the Z80) and
runs Xenix (along with TRS-DOS and CP/M). The model 12 is a Z80 only, and
runs CP/M and TRS-DOS, although I belive the 68K board can be added later.
The 12 was actually made later than the 16
and supports various modes making it
compatible with 16 and 4 (?) software
(and hardware?). Infact I think the Model 12
I would be very suprised if the Model 12 could use Model 4 hardware or
software. You certainly can't directly read M4 disks in an M12 (due to
the fact the former uses 5.25" disks, the latter 8"), for example.
-tony
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6678
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2 comments
3 participants
participants (3)
-
aliensrcooluk＠yahoo.co.uk -
ard＠p850ug1.demon.co.uk -
julesrichardsonuk＠yahoo.co.uk