Roy J. Gromlich wrote:
> I suppose I didn't expect much help from them, but their attitude has
> been go away & don't bother us.

I think their attitude is completely reasonable, assuming the product was
out of warranty (which I gather from your description it is).  They have met
all their obligations.  Supporting people who want to open the scanner and
monkey with it was never part of the deal.

Scanners are high volume products where every penny matters.  It is quite
reasonable to design such a product to be unserviceable in return for lower
cost per unit.  Many products are designed that way today.  The labor to
diagnose and then correct a problem exceeds the cost of building a new one.
Therefore there is no need to create the documentation and train techs,
again allowing the product to be cheaper.  You said your price for a whole
new scanner is about $80.  As you pointed out, the most expensive part of
producing a new scanner is probably the optical setup and associated test
and calibration time.  The cost of a new fully assembled circuit board is
probably around $10.

> There are no obviously overheated chips, nor caps for that matter.
> But then tantalums either show no changes, or else crack open if they
> get hot enough.  I had planned to go over the controller card looking
> for the changing voltage, and then following it back to the source.
> However, that would be a whole lot easier with a schematic to follow.

So how long have you spent on this, including time to complain about it
here?  Even if you had a schematic, how long would it take to diagnose the
problem, find the part or parts that got fried, get replacement parts,
remove the old, install the new, and hope that nothing else more subtle is
still wrong?  $80 for a new scanner sounds like a better deal.

> As for releasing schematics, I have never really understood the issue.
> In the case of a scanner, most of the complexity and cost is likely to
> be in the optical hardware, and ultimately the firmware controlling the
> hardware. If I wanted to clone the scanner it would take me longer,
> and cost a lot more, to duplicate the optical hardware & the firmware
> than to simply copy the circuit board.

But there is absolutely no upside in releasing the schematic, and a bunch of
costs, not the least of which is having to answer questions from people who
thought the schematic gave them license to screw around and ended up
breaking something.  There just is no win in it.  Look at the amount of
their time on the phone you already wasted.  Imagine how much more of that
would happen if people had the schematic in their hands.

> Let this be a warning to designers - don't rely on an external plug-in
> regulated supply alone to protect your hardware. Especially when using
> a standard plug & jack pair as would be found on any unregulated wall
> wart. Had this scanner had a voltage regulator on the main board, or a
> different type of power plug to the regulated supply, it would not have
> mattered if the wrong wall-wart was plugged into it.

In this one case, a more expensive design might have saved it.  However,
think about how many scanner would then be burdended with the more expensive
design without it ever providing an advantage.  Most people are going to
plug the thing in with the wall wart that came with it, and probably leave
it that way until they retire the unit well after its warranty expires.
Good design is about chosing the right tradeoffs, which is never "best" from
all angles.  Protecting against the 1 in 10,000 case of someone plugging in
the wrong wall wart isn't worth it.  It's better to make it a dollar cheaper
and have slightly more sales.

Also, you know you screwed up here, and it's not fair to blame the
manufacturer.  The company has delivered everything it promised for the
relatively little money you paid.  $80 for a complex piece of precision
equipment like a scanner is really amazing then you think about it.  Imagine
how much it would have to cost if the lifetime volume was only 10,000 units.

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