4 Jul
2007
4 Jul
'07
3:32 a.m.
Tony Duell wrote:
I'm guessing it is: There's an external motor in one corner of the unit; I
can't read most of the label, but the "0.9 deg./st" that I can see would
suggest it's a stepper.
It spins up,
by the sounds of it, but is not talking to the computer.
There's no head noises of any description.
Is it old enough to be a stepper motor positioned? Some of those do not
restroe to cylinder 0 at power-on, so the heads won't move unless told to do
so by the controller board. It's possible there's a problem with the
controller, therefore. >
> Where would I start in trying to diagnose & fix this drive? I have an
elderly
> oscilloscope, but little else in the way of
diagnostic tools (no logic
> analyser, for example). Or am I better off considering it scrap & trying to
> find a working replacement? Personally, I'd prefer to resurrect this one if
I
> can.
I assume this is a normal ST506 interface. I'd
start by looking at the
signals there -- is the machine trying to select thr drive, does it send
STEP pulses, and so on. At lest then you'll know which drvice (controller
or deive) has the problem
OK, that will give me something to work on, once I've figured out how to
re-assemble the thing whilst leaving the control board accessible....
I couldn't tell you if this was a normal ST506 i/f. The control board on the
drive has "TM600 uP 187345" printed on it; the Sirius' controller board has
only "XEBEC SYSTEMS INC." and "Assy 104526 rev-07" as identifying
marks.
Does any of that help at all? I've not looked for any schematics yet, I guess
that's the next thing to do.
Cheers,
Ade.
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4 Jul
4 Jul
2:49 p.m.
I'm guessing it is: There's an external motor
in one corner of the unit; I
can't read most of the label, but the "0.9 deg./st" that I can see would
suggest it's a stepper.
It certainly sounds like it :-)
>
> Where would I start in trying to diagnose & fix this drive? I have an
elderly
> oscilloscope, but little else in the way of
diagnostic tools (no logic
> analyser, for example). Or am I better off considering it scrap & trying to
> find a working replacement? Personally, I'd prefer to resurrect this one if
I
> can.
I assume this is a normal ST506 interface.
I'd start by looking at the
signals there -- is the machine trying to select thr drive, does it send
STEP pulses, and so on. At lest then you'll know which drvice (controller
or deive) has the problem
OK, that will give me something to work on, once I've figured out how to
re-assemble the thing whilst leaving the control board accessible....
I couldn't tell you if this was a normal ST506 i/f. The control board on the
drive has "TM600 uP 187345" printed on it; the Sirius' controller board
has
only "XEBEC SYSTEMS INC." and "Assy 104526 rev-07" as identifying
marks.
Do the cables look like an ST506/ST412 interface? (34 pin control cable,
20 pin data cable). I am pretty sure an unmodified TM502 has that
interface, Xebec were known for making ST412 controllers, so I am
guessing it is.
Does any of that help at all? I've not looked for
any schematics yet, I guess
that's the next thing to do.
Somewhere (and it'll take some finding) I have my own hand-drawn diagrams
of the floppy-drive version of the machine. No help on the hard disk
controller, but at least I'd have the interface connector pinout.
From what I remmeebr (and I hope I'm remembering
the Sirius and not some
other IBM-incompatible), the data bus is multiplexed with
the low half
of the address bus on the interface connector -- in other words it's a
buffered version fo what you get on the 8088's pins. The add-on card has
to latch the address, etc.
-tony
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