RE: Testing Step Motors

> -----Original Message-----
> From: PTENGIN@... [SMTP:PTENGIN@...]
> Sent: Thursday, November 18, 1999 1:37 PM
> To: dharrison@...
> Subject: Re: [CAD_CAM_EDM_DRO] Testing Step Motors
>
> I got my driverack with the DM4050
> drivers. What a mistake. MicroKinetics doesn't even filter in coming power
> in
> their design. I had my father go over the electronics and he also said the
>
> filtering on the pwr 3610 power supply was inadequate. I put in parallel
> some
> 58,000uf at 50 volt power caps and smoothed it a little but I need larger
> supplies. The lines from the input connector to the driver cards are not
> shielded on mine. I was getting all kinds of crosstalk. Lost steps,
> additional steps, all around instability. We also found that opto isolator
>
> power to the optistep card from the driverack was dirty. We put some
> filtering on the optistep card's external power line. We put a 20 amp
> inline
> filter unit on the 120 VAC input power. We also replaced the power leads
> to
> the motors with shielded cable. The DM-4050's were prone to overheating so
> we
> got AMP 7080 driver cards instead. These are 7 amp 80 volt cards from
> Applied
> Motion Products.
>

Peter;

I got the Driverack running over the holiday weekend. It misses and
gains steps just as you describe. In twenty inches of travel it gained
about a quarter inch on the X axis. You mentioned that the opto supply
voltage was dirty. This could be because Microkinetics also ties this +5V
supply to the input side of the drivers to pull up the enable lines. Very
bad idea. At rest I got about 6VAC (according to the O-scope) superimposed
on this +5V source. During axis movement nearly every wire in the box has
noise on it.

I called Microkinetics yesterday and was told no problems like this
had existed before (uh - right) and that I must be doing something wrong.
The arcing in the cabinet (which is why I sent it back the second time) was
never located or fixed. I traced it down to a 120V wire they pinched under
the heat sink of the X driver during the first repair.

The optistep board is acting up and I have been instructed to return
it for replacement. I just bought Doug Yeager's CNCpro software and look
forward to using it instead.


Doug Harrison

FOR SALE: Optistep board and Millmaster software. Dirt Cheap.
Working, yes. Functional, no.