Re: [APML] (OT?) got the STV, and questions about it & Losmandy

[dtlocke <dtlocke@flex.net>]

Thanks for the detailed info. The polarity is definitely opposite and is an
accident waiting to happen!  Incidentally, in the process of checking the
polarity of my DC power connection, I found that the STV power supply is putting
out about 17.1 volts, which seems to me to be quite a bit higher than the ~14V
or so from a car battery.  I have a note into SBIG about that, too.

BTW, the clear red plastic piece that fits over the LCD to reduce brightness no
longer is attached via a hinge assembly in new STV's per SBIG.  Whatever it was
apparently broke all the time.  No wonder I couldn't find the hinge assembly in
my package!

I'll let the list know what sort of responses I get from SBIG and/or Losmandy.

-Dick

k 50 wrote:

> The issue of current draw is certainly true and is a good
> reason to not hook the STV (or your dew heaters) to the
> Losmandy controller.  You also should be aware that the
> Losmandy and STV use opposite polarity, but physically
> similar power plugs!
>
> The GM8 and G11 use virtually identical electronics boxes.
> I believe a PROM is the only difference.  In both cases,
> the "common" line to the hand controller is *not* connected
> to ground (negative side of 12V input).  Consequently
> connecting it to true ground via a typical CCD guider will
> cause a current to flow, blowing something out (in one
> case it was the 5V regulator on the Losmandy board).
> However if the guider has isolated outputs as the ST4 and
> STV do, then the connection between the two is avoided,
> and there is no electrical problem.
>
> Bottom line:
>
>    - Make sure your STV power connection is the correct
>      polarity.
>    - Don't connect the STV power cable to the Losmandy
>      electronics box.  Instead connect directly to your
>      battery or 12V power supply via a separate power cable.
>    - STV guider control lines can plug directly into the
>      GM-8 or G11 because it has relay isolation.
>
> If anyone knows why the Losmandy is designed this way, I'm
> listening.  I haven't gone so far as to trace the circuitry
> to figure out what is happening.
>
> >I'm not an EE, but it is my understanding that the STV takes
> >about 2 amps to operate.  There is a fused connection to the on-board 12v
> >supply from the losmandy.  If you draw the power through the controller,
> >you may blow fuses.
> >Try a splitter from the battery with separate fuses, or separate 120v power
> >supplies.
> >
> >Regards,
> >
> >Paul Hunsberger
> >http://www.paulandpeggy.com
> >
> >-----Original Message-----
> >From: owner-astro-photo@seds.org [mailto:owner-astro-photo@seds.org]On
> >Behalf Of dtlocke
> >Sent: Monday, February 12, 2001 9:43 PM
> >To: astro-photo@seds.org
> >Subject: [APML] (OT?) got the STV, and questions about it & Losmandy
> >
> >
> >All,
> >
> >Got my STV last week after a fairly short wait through Anacortes.  I was
> >able to get it running the first night despite zero guider/CCD experience.
> >The biggest
> >problem was figuring out how to focus while dodging the clouds (with numb
> >hands).  Haven't tried it as a guider yet, and I haven't tried the efinder
> >thing
> >as it is out of stock.
> >
> >I had a bit of panic when I found my hand controller didn't work.  I
> >realized that the splitter I bought for both the CCD input and the hand
> >controller
> >input only had 4 wire; need 6.  Anybody got an extra six pin splitter???
> >Radio Shack didn't seem to have 'em either in stock or in their catalog.
> >
> >I'm getting conflicting info on this matter and I'd like comment from
> >anyone with first hand experience:  What's up with powering a GM8 & STV
> >from the
> >same source?  One person told me he does it with no problem.  SBIG seems to
> >recommend their relay box be used, but I have an email into them with
> >specific
> >questions.  Email to Scott hasn't been returned.
> >
> >The GM8 manual has the following:  "Can I plug my SBIG auto-guider into the
> >same power source as my drive system? Yes and no. The ST-4 and ST-5 can be
> >plugged into the same power supply. The ST-6 and greater can NOT be. You
> >must have a
> >different power source, they can NOT be tide together in anyway."
> >
> >Any EE's out there care to explain why this is an issue in the first place?
> >;-)
> >
> >-Dick
>
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