Re: Dirty Little Secrets (response)

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...> wrote:

>
>
> dakota8833 wrote:
>
> >deanc500 wrote:
> >
> >Hi Frank, I saw your post on the err/reset problem as I was

scouring

> >the archives for more info. I am still having major problems on

one of

> >my controllers and I am looking for possible solutions. The drives
> >fault really really easily when the err/res pins are tied together.
> >Any Ideas on a fix yet?
> >
> >Thanks
> >Dean
> >
> >
> >
> >
> >After replacing two of the drives I got my system to work with the
> >err/reset pins tied together.
> >I talked to Marriss in the past and he said to add a cap. between

the

> >err/reset and the encoder ground. He also said to try a resistor in
> >line. Since my system is working I feared tampering with it.
> >I had scoped the err/reset pin and found a lot of noise. It is my
> >belief that the noise from one drive adds to the noise already

present

> >in a drive thus causing the fault. As current demand from the

motor

> >increases so does the noise current. So far Marriss is no help. I

am

> >thinking about posting the subject called " Dirty little

secrets ".

> >It is about product reliability and what manufactures don't want

the

> >consumer to know. I know this because I'm a former auto

electronics

> >tech. I can tell you this , many electronic components failed just
> >outside the warranty period. If the failure rate was high and we

got

> >a service bulletin telling us, we replaced the components for

free.

> >We were told not to tell anyone that there was a mass problem.
> >Unfortunately the only person that can fix this problem is Marriss.
> >
> >
> Well, the G201's only have a disable input, not an error/reset

terminal.

> But, since
> there is such a problem on some other models, I did my

enable/disable with a

> multipole relay. I used one normally closed contact to disable

each

> drive unless the
> relay was energized. I don't know which Gecko drive you are using,

but

> you may
> be able to come up with a similar solution, using separate relay
> contacts to reset
> the drives, and one opto-isolator on each drive to sense the fault
> condition and
> or them together to inform the CNC control software of that

situation.

>
> Jon

I agree with Jon. The Err/Res pin is referenced to the internal
Gecko buss and should be isolated from outer inputs. Tying the pins
together would increase the possibility of cross noise issues. One
quick and simple solution would be to put a cap (small disc type)
from the Err/res pin to Encoder -. A good value to start with would
be .01 mfd. I am running my 340's on a plasma table and noise is
rampant. I have had to pay close attention to common point grounding
and bypass caps on most of the drive and power lines to get things
under control. As a component of a complex assembly it is up to the
designer of that assembly to deal with properly interfacing
components to it. Unlike finished goods (like if you paid big bucks
and bought your CNC unit completely assembled with a warranty - like
a car) the suppliers of components and sub-assemblies are not to be
held to the same level. I do not blame Mariss for my noise problems
on my design and I don't expect him to offer more than suggestions.
I have used other vendors products and the support you get from Gecko
far exceeds most others. Most of us that have chosen to build our
own machines accept the fact that we are trying to do so with the
least expense and that means using parts and pieces from various
vendors in designs that none of them have control over. I have the
expertise to design and build my own motor controller. Were I to do
so, I would face weeks of troubleshooting little design problems and
still have to pay for the components and PC boards. When commercial
mfgs were getting 350 to 600 bucks for a 5A stepper motor controller
it was a strong consideration. When they cost 114.00 it's a no-
brainer to buy vs build.

There are lots of dirty little secrets in this hobby. Gecko is not
one of them.