RE: [CAD_CAM_EDM_DRO] MAXNC 10

> -----Original Message-----
> From: Alan Marconett KM6VV [mailto:KM6VV@...]
> Sent: Thursday, November 08, 2001 1:50 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: Re: [CAD_CAM_EDM_DRO] MAXNC 10
>
>
> Hi Chris,
>
> I get 5V from mine! I have a 1K pull-up for the probe line
> (pin 13). I
> need to add another pair for limit switches (not that I'll
> necessarily
> add them to the Sherline), and a E-stop switch (this I think I WILL
> add).
>
> I agree, the design is on the "low cost" end. Reminds me of
> a story in
> the late 60's about how Muntz tv's were supposedly designed.
> Story goes
> that "Mad Man Muntz" start with a TV design (perhaps a
> competitors), and
> start removing parts, continuing to remove parts until all
> that could be
> removed without the TV failing were removed.
>
> Alan KM6VV
>
>
> Christopher Coley wrote:
> >
> > Has anyone looked at the control box on the MAXNC. Last
> night I was looking
> > for a 5V source in the control box to add a pull-up
> resistor for Limit and
> > Digitizer inputs.
> >
> > The controller card has a five volt regulator but when
> measured the output
> > was only 2.3V. This is used to power three SN7400 NAND
> chips that are used
> > as buffer inverters to drive the drive transistors,
> DIRECTLY no limit
> > resistor, with a 1K pull-up to VCC (2.4V). This is where
> the load is that
> > is limiting the VCC.
> >
> > I ended up rewiring and modifying the controller so that
> it now has the
> > SN7400 output go through the resistor to the transistor
> without the pull-up.
> > Now I have a real 5V in the box.
> >
> > Has anybody else experieanced these issues. I think that
> MAXNC screwed up
> > majorly and thier configuration is bound to fail eventually.
> >
> > Chris.
>
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