Re: Lost steps

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.