Re: Unexpected slews - AP1200GTO


Hi Anthony, all,
We have similar frustrations, but likely different answers. First it
is very important to have a real power supply (like the AC power
supply AP offers) or a well maintained battery that will have low
enough source impedance and ampere hour capability to drive the
system at high speed, which requires several amps, NOT milliamps,
AND not drop under 12 VDC. I use a full size 105 AH Stowaway in a
battery case for long star parties and never run low of power.
I have a similar run-away drive problem, which I have been fighting
with for 5 years on my AP900. I have spoken to Howard about it, who
offered to check it out but I would have to lose it for a while, and
for reasons like Mars, or Jupiter or new comets, I have not sent it
in yet. Someday I will have to. But it can work fine for a while,
then one night out of the blue it will take off repeatedly and has
driven my scope into the pier several times (!!) shrieking at 1200x
rate. Only then do I ever get an overload light, for very good
reason. I have frantically started unscrewing the lock ring on the
power cord plug on more than a few nights when the stop button would
not stop it, and live in fear of that dreaded sound. It does make
for a bad night. The standard recommendations are to spread the
loose power plug split pin wider for better contact, and checking
the power and Y cable for open circuits. I have no power supply
problem and I am sure the cables and connectors are good. I have
learned to not bother recalibrating the system again after 3
failures in any one night. I could send it in for service or just
use it to track. I often just use it to track and move it by hand,
or use the key pad for motions and options, but do not push GO-TO
for fear of another runaway, which is especially freaky if I hit the
stop key. Only recently I have been getting the message of "object
below horizon", so now Go-To does not work anyway. I recently
learned here that I can fix that if I change the memory battery and
learn how to download a program into the control box.
I will be looking to see what you learn.
Fair skies,
Bob Cuberly

--- In ap-gto@..., "ayiomamitis" <ayiomami@...> wrote:
The most puzzling part of all is that everything was working
fine the
other day for the first 30-45 minutes when I started my usual
of cooling the CCD camera, finetuning focus, centering my
properly etc ... a few minutes before my intended start time
the problems started (while connected and everything humming
Hi Bill,
In my mind you have not actually verified the power source ?.
Until that
I have tried three sources of power ... my original battery with
which the problems started, the new battery purchased today as well
as one of those portable 17Ah batteries which I was using originally
with my AP1200GTO. In fact, for the latter, I tried three such 17Ah
batteries which I now use for my Kendrick dew system.
is done you might be chasing rainbows. Certainly you must have
a 110 <=>13.8 VDC power supply to run some tests with ? Even a 3

I have a transformer for 230v to 3/4.5/6/7.5/9/12v but I have no
to test the proper polarity (I am electronically illiterate). It
supplies 300mA which I recall being too low on the basis of a
message to Rolando.

supply is enough to isolate the problem. It is not enough
current to
actually use though. Batteries are notorious at not producing
voltage and or current. Roland has suggested that this should be
verified *first*. And past threads have confirmed this wisdom.
The only piece of the puzzle which I cannot confirm one way or
is my Y-cable. Now, if this was also ruled out as a potential
spot, I would be out of options.

Then again if you have done this and I missed that then I
every one of these symptoms sounds like a power problem.
Please do not apologize. I am so frustrated and desperate that ANY
suggestion and thought is most welcome.

I must wait till Monday to see what Rolando and Howard can suggest.


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