Re: [CAD_CAM_EDM_DRO] Re: Lost steps

Been following this thread and some interesting ( and good ) ideas have been advanced but I'll throw out one more. When in doubt
drop back to basics. This assumes you have a few chips to play with or a computer with some parallel bits to play with.
Make a set of drivers so each bit switches a stepper coil off or on. Set up a bit sequence to step the motor either forward or
back. ie. some of this was shown in the discussion on the 5 phase states.

Use the computer to step thru the sequence. Try different step rates, and supply voltage, dropping resistors in series with each
winding. Since this in independent of the orginal setup, except for power supply it may give you some hint of what is picking on
you. Best of luck.

Dave

Ozzie@... wrote:

> Okay we have some discussion of wire sizes, power supply, decoupling
> caps!
> The main power supply is two transformers, 10A each in parallel,
> feeding to a rectifier and then a big capacitors, all supplied by
> Camtronics, with knowledge of what I was building.The wires supplying
> motor voltage to the boards is 18 Ga stranded wire, +and-. It's not
> shielded.There are two capacitors right at this power connection on
> the board.
>
> The motor wires coming from the board to the connectors in the back
> of
> the case are 16Ga stranded, now home shielded with foil.
>
> The signal wires from the DB25 junction board are 22Ga stranded, home
> shielded with foil. The shielding is wrapped with some bare wire and
> then grounded to the chassis.
>
> The 5V power supply is built as instructions given to me by Dan via
> e-mail. The main power supply run through a resistor, a 5V regulator,
> and two capacitors. The 5V then goes to the boards through 18Ga
> wires.
>
> All of this is redundently grounded to the chassis/case. The power
> cord is grounde, the rectifiers are grounded, the 37 Volts is
> grounded, the 5Volts is grounded, and each board is grounded on all 4
> corners to the ground trace which also grounds both power supplies.
>
> The fan runs on the transformer AC, and those wires are now home
> shielded.
>
> The driver side of the DB25 cable has all unused wires grounded and
> the port end I don't know about, but it is a very standard port card,
> screwed to the housing/case in the normal manner. It is a commercial
> cable and the pin housings show continuity to each other
>
> I don't understand decoupling caps, please explain.
>
> Hope we're getting somewhere!
>
> Jerry
>
> n CAD_CAM_EDM_DRO@egroups.com, ptengin@a... wrote:
> > In a message dated 08/21/2000 1:17:08 PM Hawaiian Standard Time,
> > jmelson@a... writes:
> >
> > << Ah, HA! Now, you are getting somewhere. Clearly, it is some
> sort of
> > interference
> > problem, radiation from the motor wires and other things are
> > contaminating
> > the step and/or direction inputs to the driver. >>
> >
> >
> > I had similar problems on mine. I installed decoupling caps and
> went
> to
> > twisted pairs of 20 or 22 ga wire for the signal, no shield. The
> problem went
> > away!! I don't recall the value of the decoupling caps but they
> must
> be small
> > as larger caps did manage to dampen the pulse when observed on a
> scope.
> > Perhaps Jon would have the value off the top of his head. I'd have
> to drive
> > out to my dad's place to look/see. Good luck
> >
> > Peter
> > THRD, Inc.
>
>
>
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