Re: Mount does not stop Update

Howard Hedlund

Hi Dean and Group,

I spoke with Dean about the issue this morning, and I thought that I
should make a few trouble-shooting comments to the group as a whole.

* We always recommend that you have the latest firmware versions
installed on your keypad. The current version, v.4.12 has been a very
stable and trouble free version. It has fixed any bugs that were in
previous versions. For any of you who have not yet upgraded, I suggest
you do so. Unlike some other software company who shall remain
nameless, our latest version really is better, and it's free!
Likewise, it is always a good idea to have the current version ROM chip
installed in your GTOCPx servo control box. These chips aren't free,
but they are very reasonable, and are relatively easy to upgrade.
* When you are having a problem with your electronics, it is
always a good idea to start with simple solutions first. Verify your
power supply. Verify the integrity of your cables. Make sure you have
good connections and that contacts are clean and free of oxidation.
Intermittent or inadequate power can cause all sorts of strange behavior
in servo control electronics, and poor connections can interrupt or
corrupt communication between various components in a system.
* Be sure that you don't have a mechanical issue. This mainly
means be sure that your motors can turn the worm. Check this by turning
the spur gear as Roland has outlined many times to this group.
* The motors in the servo drive system must be fed voltage by the
servo system to operate. Although there is a very sophisticated control
system involving communication from the motors' encoders back to the
servo, back to the motors etc., the motors or the mount cannot demand
power or "suck" voltage from the system. They can only turn if the
servo logic decides to feed them the necessary electrons. If they are
turning when they shouldn't, it is because they are being fed voltage
when they shouldn't. The question is why are they being fed?
* There are really only two possibilities here. (I left out
operator error since I have full confidence that Dean can press and
release a direction button!! ;-) Either the servo is being instructed
to feed the motors by erroneous instructions from the keypad or
computer, or else the servo is erroneously feeding voltage to the motors
without being told to do so. In this particular case, we had the
problem showing up both when the keypad was giving the instructions to
the servo and when PulseGuide was giving the instructions via an
external computer. Since it is highly unlikely that both the keypad
and PulseGuide would develop the exact same bug at exactly the same
time, we are focusing attention on the GTOCP2 servo control box.
* We decided to start by checking out all the items noted in the
first three bullets above and by upgrading the ROM chip to the latest
version - the "E1" for his GTOCP2. The chip upgrade was something Dean
could do himself, and it was a recommended item anyway. Hopefully,
replacing the chip will cure the servo. If the problem does persist,
we will have eliminated most of the potential culprits making the repair
job here at Astro-Physics much easier (and therefore hopefully a bit
cheaper too!).

This has been a rather long narrative, but I thought it might be
instructive for you to see how the problem was approached. Any of you
who follow the group will have seen the posts and will know what has
been going on. I will provide a (much shorter) follow up when Dean's
mount is performing flawlessly again.

Mag. 7 skies!

Howard Hedlund

Astro-Physics, Inc.



From: ap-gto@... [mailto:ap-gto@...] On Behalf
Of Dean Salman
Sent: Sunday, August 12, 2007 2:03 PM
To: ap-gto@...
Subject: [ap-gto] Re: Mount does not stop Update

This is now serious problem. I have changed power supplies and there
seems to be no issue with the gears. The software in the mount is
4.0x, is that the problem. This happens at any speed including 1x and
both axis. I do know someone with a 1200 mount near by so I guess I
can change out parts but this is looking like a mount issue, not the
control box or key pad.

--- In ap-gto@... <> , "Dean
Salman" <cluster@...> wrote:

When I use the keypad, sometimes the mount will continue to slew so I
have to press stop. I thought it was the key pad but PulseGuide did
the same thing without the keypad. Someone told me it was in the
controler box. So far I have not seen this using the Sky or CCD
Commander. Anyway thoughts ?


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