RLM wrote:

On Tue, 25 Sep 2007 14:02:55 -0500, Pete C. wrote:

Ignoramus30458 wrote:

On Tue, 25 Sep 2007 13:45:39 -0500, Pete C. wrote:
Ignoramus30458 wrote:

On Tue, 25 Sep 2007 13:36:16 -0500, Pete C. wrote:
Ignoramus30458 wrote:

Can you clarify just what is wrong? What kind of encoder is it? Can
you replace it with a generic part?

i

I expect that there are few to no custom electronic components in any of
these machines beyond a microcontroller chip and perhaps a PAL chip.
Most of the components should be readily available from Digi-Key. I
expect the encoder in question is about $10 from Digi-Key.

When I hear "encoder", I do feel like it is probably generic. What
kind of isolation testing has the OP done so far? What makes him or
his dealer conclude that it is an encoder?

i

I found a previous thread discussing this a few months ago. In there it
is indicated as a device that looks like a pot, has three connections to
the PCB and continuous rotation. I suspect it's a $5 mechanical rotary
encoder that is quite standard, available from Digi-Key, and could be
upgraded to a more reliable optical version for a few dollars more if he
can find a 5 volt supply for the optical version.

That makes sense, but how does the OP know that it is malfunctioning?

i

The report was that the amperage set point made wild jumps when trying
to adjust, i.e. dirty mechanical encoder contact bounce. I expect either
of us could repair the machine at minimal cost in a minimal time.
Unfortunately you aren't very likely to find someone with component
level troubleshooting expertise at a welding supply shop.

You may well find someone with the ability to troubleshoot and
repair things at the component level but the management know that the
customer will complain about the cost of troubleshooting time and the
labor to replace the inexpensive component parts. The warranty will be
limited, if any, and if the failure of the one component has stressed
another component and it fails in a short time the manager eats the
warranty.
The customer looses faith in the dealer because, in his opinion, it
wasn't fixed the first time right. These are the hardest customers to
win back.

Replacing a board (card) insures the manufacturers warranty and the
manufacturer will reimburse the dealer and recall the faulty part to find
the problem and improve future models or may offer a recall on the part if
it shows chronic failure rates and possibly replace it free.

The OP should ask if perhaps there is a recall in effect that may have been
over looked. Poor management tend to pigeon hole information that they don't
understand. I've known service managers that couldn't put lead in a
mechanical pencil or were amazed that it was even possible.

There are those issues as well unfortunately...