SLA7062 and Re: New Article Posted

Dave,

Did your instructions discuss ground potential isolation in any
manner whatsoever? Mine didn't. Further I could not get an answer
from HCNC support on if, how and why it was necessary.

If it is needed, I'd think that either it should be stated clearly
in the instructions along with recommendations of appropriate
optoisolation boards, or the board should be redesigned to include
optoisolation of the DB25 port.

If not, perhaps some simple protocol to determine if a particular
configuration has isolation problems would be helpful. In my case,
both the PC and the power supply/HCNC board shared the same outlet
strip and thus the same ground...one would tend to think that was
adequate with properly grounded devices. Guess not.

Tom



--- In CAD_CAM_EDM_DRO@yahoogroups.com, Codesuidae <codesuidae@...>
wrote:

>
> jeffalanp wrote:
> > So it would appear that the SLA7062 is perhaps not as robust as

has

> > been previously suggested. I guess they do go 'pop' as well, if

they

> > are abused, similar to an abused A3977SED.
> >
> > This would most likely be to shorting of phases to one another

or

> > ground, as the disconnect is generally covered by the internal

diodes

> > I mentioned before.
> >
>
> I blew up a couple of mine when I first powered up my HCNC board.

In my

> case I was using a temporary non-isolated power supply and blew up

both

> the laptop computer and the HCNC board. I was aware that it would
> happen and had intended to run the laptop on batteries to avoid

the

> issue, but then forgot to do so and powered up with the laptop and
> controller board both connected to the wall. Toasted a PCB trace

killed

> the computer (an old 486 laptop) and blew the direction inputs on

two of

> the 7062's.
>
> After fixing the isolation issue and the the pcb trace I found

that all

> four axis on the controller board would power up and lock the

motors

> with the appropriate hissing noise, and that one of them worked

fine,

> two would step in one direction but not the other, and one

wouldn't step

> at all. I guessed that the direction inputs on two and at least

step on

> the other were blown. I bought three new chips, swapped them out

and it

> all worked as it was supposed to.
>
> Dave K
>