On Friday, October 21, 2011 09:31:58 PM Jon Elson did opine:
> gene heskett wrote:
> >> With only the encoders plugged into the PPMC boards the D-sub
> >> connector does not show ground.
> >> OK let make sure I am saying this right with only the encoder
> >> plugged in and my meter set to ohms, one lead on the D-sub
> >> connector and on on the chassis it shows an open circuit. If I plug
> >> in the amp to the DAC or the parallel cable my meter shows a dead
> >> short. Not that this helps of changes anything I just want to make
> >> sure I am explaining it rigth
> >
> > I would go to the far end of this cable and opern up the dsub shell
> > and break the connection there. It is making a ground loop.
>
> again I am not clear what we are talking about. But, I think Bruce
> means that
> when the DAC is plugged into the servo amps, there is a ground
> connection. This isn't at the encoder but at the servo amp.
> There MUST be a ground to the servo amp COM terminal, it is the
> reference for the velocity command!
>
>
> Jon
Sorry, been out of pocket most of the week, retrieving a 40kw rated tv
transmitter I am going to use as a linear amplifier for the local channel
5, we have perms to raise our power. Its true, you can't retire. Ever...
Back to you, and that d-sub. With the shell split, there should be 2 small
bolts holding to together, and removed (pay attention to the two screws
that attach it to the mating connector), you should find a wire soldered to
the back edge of the thin metal frame around the plastic pin carrier. It
is this connection that needs to be checked to make sure it is grounded at
the src end of the cable. Then check to see if there is a ground on the
frame of the connector it plugs into. If there is ground at both, then cut
the wire soldered to the edge of the shell frame, cut it back to the cable,
wrap a turn or two of plastic electrical tape to insulate it so it can't
touch anything and re-assemble the backshell. Don't lose the 2 screws on
the end that are used to attach it to the mating connector.
Cheers, Gene
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Hangover, n.:
The burden of proof.
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