Semi-OT: IDE & SATA to USB "dongles"

[Tony Duell]

> 
> Tony Duell wrote:
> Thing is, the electronics of the older drives uses simpler ICs, and =
> fewer
> custom parts. I would much rather repair an ST412 (for which I have
> schematics anyway) than the IDE thing I've just looked at.
> -----------------------------------------------------
> Billy:  I've data from 3 different disk drive companies over 20 years =
> and
> 100+ million failed drives, that show the same thing:  PCB failures are =
> less
> than 1% of the total field return failures.  The vast majority are =

This does not mean electronic failures do not happen. The last 'classic' 
drive that failed here was a Micropolis 1200 series (8" Winchester-type). 
The fault was the servo amplifier chip, an LM379. Getting a replacement 
was 'fun' (and it has to be that device, the unit uses the property that 
the 'bottom end' of the output stages of the 2 amplifiers are brought out 
to separate pins), but fitting it was trivial.

> tribology
> related (heads and media).  I know a few specialty companies that can
> recover data from crashed drives.  But I know of none that try to repair
> crashes.  The cost is hundreds of times greater than buying a new disk.

But hos does it compare to building an interface circuit to use the 
current drives on a machine that was never designed to use them? Perhaps 
you'd like to design a PERQ EIO card -> SATA interface. 


> ------------------------------------------------------
>  > circuitry in the surplus stores. But it's the heads and platters that =
> =3D >
> wear > out and ferrite heads and oxide media are gone. Occasional bits =
> and=20
> 
> True. But other problems inside the HDA would be much easier to repair =
> on an
> older drive with a much larger head flying height. I think it would be
> possible to make a 'clean box' to open up ST412s at home and repair them =
> and
> expect the repaired HDA to be reliable enough to use. That is not the =
> case
> with modern drives.=20
> -------------------------------------------------------
> Billy: I'm not certain what you think can be repaired in an old ST412.  =

>From your comments below I am not even sure you've seen an ST412.

> I
> know you can't make the media or rewind the heads, so I assume you are =
> only
> talking of substituting parts from another unit.  Which may be in just

I was thinking of spindle motors problems, positioner problems, track 0 
sensor problems, etc.

And yes, moving parts from other units. I've I've got 2 dead drives, I 
might well have enough good heads and platters to make one working one 
out of the bits. This is one reason I keep old/defective modules.
 =
> as
> bad condition.  And even if you could put a new platter in, how do you =
> do
> servo track writing?

That's what makes me think you've never seen an ST412. What servo track? 
It uses a stepper motor positioner. There is no servo data on the 
platters, period.

> 
> Disk drives are not designed for decades of  life.  They're designed to =
> last
> until the next new tech is available - cheaper and faster.  Their =

Fine, if the machine you're using can take the cheaper/faster drives 
(this PC, for all it's a much hacked PC/AT, has an IDE controller and 
drive, not the origianl ST412-interfaced one). Not so good if you're 
talking about a classic computer that depends on getting the raw 
bitstream that comes over an ST412-like interface.

> solder joints, power consumption electronics, connectors, etc.  So you =
> can
> find the odd ST412 that you recover.  But is it fun?  Is it worth the =

TO me that _is_ fun...

> time
> you spend vs buying a =A320 IDE drive and having time to use your =
> system? =20

You can't possibly attempt to account for the time you spend on hobbies. 

> 
> I know we share a love of understandable electronics and hands on =
> computing.
> And especially building our own design out of logic.  But repairing old
> disks because you do not want to learn new technology seems to me to be
> counter-productive.

Not when (a) you enjoy repairing things (as I do) and (b) it's the 
simplest way to keep the computer working.


> dealing with the first electric lamps .)  It seems to me that you are
> severely limiting your fun by ignoring all the new technology that is =
> out
> there.

How can you possiibly tell me what I enjoy and what I don't? If you don't 
like gabbing a soldering iron and 'scope and diving into the logic fine, 
but don't try to critisse those of us who do.

-tony