Tandon TM 502

Ade javickers at yahoo.co.uk
Wed Jul 4 05:32:39 CDT 2007

Tony Duell wrote:

> > 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.

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.

> > 
> > Where would I start in trying to diagnose & fix this drive? I have an
> > 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
> > 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.


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