GTO Keypad Freezes Problem


Terry Johnson <tjohnson@...>
 

Marj, I spoke with Roland about a problem I was having with my 600GTO mount. The problem centers around the GTO keypad. I have explained the problem below in more detail. Would you please see that he gets this information. I will also provide a printed copy when I send you the equipment he requested.
 
 
The Problem
 
I was just completing a polar alignment process using the north polar alignment procedure, I was using Polaris and Vega as my two stars, as I was doing a final alignment on Vega, and was asked to press 'menu' to have the scope slew to polaris for the final time, I pressed the 'menu' key on the keypad and nothing happened. I pressed the key several more times and still nothing happened. I pressed other keys and still nothing happened. The keypad was locked on the 'press menu to exit' command.
 
I was able to get around the problem by turning off and on the power to the GTO control box. I now had to polar align again.
Since I was very near completing the alignment in the previous aligning process, it did not take long to polar align this time. After aligning, I slewed the scope to Vega. I then added the additional equipment for taking exposures(see Equipment, after polar aligning, below). I was going to slew to another location in the sky, however, the keypad was lock up again while on Vega. The problem was the same where the keypad was locked on the 'press menu to exit' key.
I gave up for this evening, packed up and went home.
 
The next night I was able to polar align correctly. I then added my guiding equipment for camera exposures (see Equipment after polar alignment, below) I slewed to arcturus to practice my guiding on a bright star. After having success on the guiding practice, I decided to take an exposure of M-13. I keyed in M-13 using the keypad, pressed the 'GOTO' key and the scope did not move, however, the keypad did display the information about M-13 as it normally does after you press the 'GOTO' key. I pressed other keys and still no response. I had to power off/on the GTO control box to clear the problem.
 
Possible Causes
  • I had accidentally reversed the 12V polarity to the GTO keypad and mount while connecting the system on the first night. After talking with Roland, he did not see this as a problem.
  • After changing the equipment before and after polar alignment, I did not re-balance the scope. I did not mention this to Roland, however, I do not believe an out-of-balance condition will cause the keypad to lock-up.
I would appreciate any advice or experience on what is causing this problem. Roland has asked that I send in my keypad, cables, and GTO control box to be checked out. I will send the equipment in tomorrow.
 
Thanks for your help in this matter...Terry Johnson
 
 
The Equipment:

While polar aligning:
  • AP130F6 scope with 2" 'Maxbright' diagonal, 2" to 1/125 reducer, and a Meade 1/125 9mm illuminated recticle
  • AP80X900 guidescope 1/125 diagonal and a Panoptic 12mm eyepiece
  • 600GTO mount
  • AP wood tripod
  • 2 nine pound, and one six pound counter weights
  • attached to an 88amp gel cell battery
    • GTO control box and control pad
After polar aligning:
  • AP130F6 scope with focusing extender, a 2" barlow, a canon 35mm camera
  • AP80X900 gusidescope with ST-4 autoguider
  • 600GTO mount
  • AP wood tripod
  • 2 nine pound, and one six pound counter weights
  • attached to an 88amp gel cell battery
    • GTO control box and control pad
    • 12V to 110V inverter for PC
    • ST-4 autoguider
 


rck <rkuberek@...>
 

Hi Terry,

Something like this has happened to me several times. I narrowed it
down to undervoltage, and since fixing that, it's ok.

Regards,
Bob Kuberek
 

Terry Johnson wrote:

Marj, I spoke with Roland about a problem I was having with my 600GTO mount. The problem centers around the GTO keypad. I have explained the problem below in more detail. Would you please see that he gets this information. I will also provide a printed copy when I send you the equipment he requested.


Terry Johnson <tjohnson@...>
 

Bob, when you speak of undervoltage, when do you consider the voltage to be too low. My 88 amp battery with all the systems connected puts out 12.8 volts when the battery is fully charged to 12.2 volts after six hours of usage.
 
Terry

----- Original Message -----
From: rck
Sent: Thursday, June 15, 2000 8:49 PM
Subject: Re: [ap-gto] GTO Keypad Freezes Problem

Hi Terry,

Something like this has happened to me several times. I narrowed it
down to undervoltage, and since fixing that, it's ok.

Regards,
Bob Kuberek
 

Terry Johnson wrote:

Marj, I spoke with Roland about a problem I was having with my 600GTO mount. The problem centers around the GTO keypad. I have explained the problem below in more detail. Would you please see that he gets this information. I will also provide a printed copy when I send you the equipment he requested.



rck <rkuberek@...>
 

You have tested it at 12.8 volts or that is what it is rated to produce?

I was getting under 12 volts when I had the problem. After I switched
to a marine deep cycle 60AH battery, no problems--I can run for 2-3
nights on one charge. Just the scope though, nothing else on it.

Regards,
Bob Kuberek
 

Terry Johnson wrote:

 Bob, when you speak of undervoltage, when do you consider the voltage to be too low. My 88 amp battery with all the systems connected puts out 12.8 volts when the battery is fully charged to 12.2 volts after six hours of usage.


Terry Johnson <tjohnson@...>
 

Bob, I have a voltage meter attached to the battery that displays the battery voltage. Do you know whether a short drop in voltage caused by connecting an additional CCD camera and PC would to the battery would cause the keypad to lock-up if the keypad was already attached to teh battery?
 
Thanks...Terry Johnson

----- Original Message -----
From: rck
Sent: Thursday, June 15, 2000 9:12 PM
Subject: Re: [ap-gto] GTO Keypad Freezes Problem

You have tested it at 12.8 volts or that is what it is rated to produce?

I was getting under 12 volts when I had the problem. After I switched
to a marine deep cycle 60AH battery, no problems--I can run for 2-3
nights on one charge. Just the scope though, nothing else on it.

Regards,
Bob Kuberek
 

Terry Johnson wrote:

 Bob, when you speak of undervoltage, when do you consider the voltage to be too low. My 88 amp battery with all the systems connected puts out 12.8 volts when the battery is fully charged to 12.2 volts after six hours of usage.



toddg18522@...
 

In a message dated 6/15/00 10:51:24 PM EST, rkuberek@ix.netcom.com writes:

<< Hi Terry,

Something like this has happened to me several times. I narrowed it
down to undervoltage, and since fixing that, it's ok. >>

I had similar problems when undervoltaged


toddg18522@...
 

In a message dated 6/15/00 11:14:46 PM EST, rkuberek@ix.netcom.com writes:

<< You have tested it at 12.8 volts or that is what it is rated to produce?

I was getting under 12 volts when I had the problem. After I switched
to a marine deep cycle 60AH battery, no problems--I can run for 2-3
nights on one charge. Just the scope though, nothing else on it. >>


try a battery that delivers 13-14v for awhile... I ran into problems under
12v I think


rck <rkuberek@...>
 

Terry,

Yes, I suspect that it would, but I don't know for sure.

Regards,
Bob Kuberek
 

Terry Johnson wrote:

Bob, I have a voltage meter attached to the battery that displays the battery voltage. Do you know whether a short drop in voltage caused by connecting an additional CCD camera and PC would to the battery would cause the keypad to lock-up if the keypad was already attached to teh battery? Thanks...Terry Johnson


 

Terry,
>>I have a voltage meter attached to the battery that displays the battery voltage. Do you know whether a short drop in voltage caused by connecting an additional CCD camera and PC would to the battery would cause the keypad to lock-up if the keypad was already attached to teh battery?<<
 
Roland said that this is likely to happen. Your meter is reading an average and will not show dips. Gel cells have internal resistance which will cause voltage drop when the load changes. When you connect an additional CCD camera and PC the load will drop below 9 volts and the keypad will reset or it may affect the GTO circuit itself and cause the keypad to lock up.
 
We recommend that you use a large marine battery that is not a gel cell and hook everything up to it before powering up the GTO.
Hope this helps. Thank you for providing me with another issue to address in the troubleshooting section of the manual.
 
Marj, Astro-Physics

 -----Original Message-----
From: Terry Johnson [mailto:tjohnson@...]
Sent: Thursday, June 15, 2000 11:35 PM
To: ap-gto@...;
Subject: Re: [ap-gto] GTO Keypad Freezes Problem

Bob, I have a voltage meter attached to the battery that displays the battery voltage. Do you know whether a short drop in voltage caused by connecting an additional CCD camera and PC would to the battery would cause the keypad to lock-up if the keypad was already attached to teh battery?
 
Thanks...Terry Johnson
----- Original Message -----
From: rck
Sent: Thursday, June 15, 2000 9:12 PM
Subject: Re: [ap-gto] GTO Keypad Freezes Problem

You have tested it at 12.8 volts or that is what it is rated to produce?

I was getting under 12 volts when I had the problem. After I switched
to a marine deep cycle 60AH battery, no problems--I can run for 2-3
nights on one charge. Just the scope though, nothing else on it.

Regards,
Bob Kuberek
 

Terry Johnson wrote:

 Bob, when you speak of undervoltage, when do you consider the voltage to be too low. My 88 amp battery with all the systems connected puts out 12.8 volts when the battery is fully charged to 12.2 volts after six hours of usage.





Chris Spratt
 

I use the Kendrick 17amp 12-volt battery recommended by Astro-Physics
to power their scopes. It is just adequate for my AP600E GOTO. Even
though it shows 12.9 volts on the voltmeter prior to being used this
may not be enough to power the scope. My solution (apart from getting
a larger battery)is to charge it after every observing session.

My CCD (Pixcel 237) is powered by another Kendrick 17amp 12-volt
battery. Here to the CCD won't work unless the battery has been
charged right prior to each observing session. Even if the battery
shows 12.8+ volts the CCD may not work properly.

It is best to charge after each session even if you have a larger
battery.

I feel that the the Kendrick 17amp batteries are really too small for
running a GOTO mount (or even a CCD). As for running both the mount
and CCD off one battery - a huge one is required here!



--- In ap-gto@egroups.com, "Marj" <marj@a...> wrote:
Terry,
I have a voltage meter attached to the battery that displays the
battery
voltage. Do you know whether a short drop in voltage caused by
connecting an
additional CCD camera and PC would to the battery would cause the
keypad to
lock-up if the keypad was already attached to teh battery?<<

Roland said that this is likely to happen. Your meter is reading an
average
and will not show dips. Gel cells have internal resistance which
will cause
voltage drop when the load changes. When you connect an additional
CCD
camera and PC the load will drop below 9 volts and the keypad will
reset or
it may affect the GTO circuit itself and cause the keypad to lock
up.

We recommend that you use a large marine battery that is not a gel
cell and
hook everything up to it before powering up the GTO.
Hope this helps. Thank you for providing me with another issue to
address in
the troubleshooting section of the manual.

Marj, Astro-Physics
-----Original Message-----
From: Terry Johnson [mailto:tjohnson@c...]
Sent: Thursday, June 15, 2000 11:35 PM
To: ap-gto@egroups.com;
Subject: Re: [ap-gto] GTO Keypad Freezes Problem


Bob, I have a voltage meter attached to the battery that
displays the
battery voltage. Do you know whether a short drop in voltage caused
by
connecting an additional CCD camera and PC would to the battery
would cause
the keypad to lock-up if the keypad was already attached to teh
battery?

Thanks...Terry Johnson
----- Original Message -----
From: rck
To: ap-gto@egroups.com
Sent: Thursday, June 15, 2000 9:12 PM
Subject: Re: [ap-gto] GTO Keypad Freezes Problem


You have tested it at 12.8 volts or that is what it is
rated
to
produce?
I was getting under 12 volts when I had the problem. After I
switched
to a marine deep cycle 60AH battery, no problems--I can run
for 2-3
nights on one charge. Just the scope though, nothing else
on
it.

Regards,
Bob Kuberek


Terry Johnson wrote:

Bob, when you speak of undervoltage, when do you
consider the
voltage to be too low. My 88 amp battery with all the systems
connected puts
out 12.8 volts when the battery is fully charged to 12.2 volts
after
six
hours of usage.

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Terry Johnson <tjohnson@...>
 

Chris, I believe my keypad locking problem was probably caused by a dip in
voltage after I powered on my ST-4 and 12V to 110V inverter that I use to
power my PC. I watched the volt meter when I powered up the 12V inverter/PC
and saw the battery voltage go from 13.2V to 12.6 and then settle in at
12.8. I have a feeling the GTO control box is very sensitive to power drops
and therefore causes the keypad to lock. I now plug all of my components
into the 12V 88 Amp battery first. I then connect the 600GTO control box as
the last unit, whichs seems to have taken care of the problem. Just another
learning curve.

...Terry Johnson

----- Original Message -----
From: "Chris Spratt" <cspratt@islandnet.com>
To: <ap-gto@egroups.com>
Sent: Saturday, June 17, 2000 6:51 PM
Subject: [ap-gto] Re: GTO Keypad Freezes Problem


I use the Kendrick 17amp 12-volt battery recommended by Astro-Physics
to power their scopes. It is just adequate for my AP600E GOTO. Even
though it shows 12.9 volts on the voltmeter prior to being used this
may not be enough to power the scope. My solution (apart from getting
a larger battery)is to charge it after every observing session.

My CCD (Pixcel 237) is powered by another Kendrick 17amp 12-volt
battery. Here to the CCD won't work unless the battery has been
charged right prior to each observing session. Even if the battery
shows 12.8+ volts the CCD may not work properly.

It is best to charge after each session even if you have a larger
battery.

I feel that the the Kendrick 17amp batteries are really too small for
running a GOTO mount (or even a CCD). As for running both the mount
and CCD off one battery - a huge one is required here!



--- In ap-gto@egroups.com, "Marj" <marj@a...> wrote:
Terry,
I have a voltage meter attached to the battery that displays the
battery
voltage. Do you know whether a short drop in voltage caused by
connecting an
additional CCD camera and PC would to the battery would cause the
keypad to
lock-up if the keypad was already attached to teh battery?<<

Roland said that this is likely to happen. Your meter is reading an
average
and will not show dips. Gel cells have internal resistance which
will cause
voltage drop when the load changes. When you connect an additional
CCD
camera and PC the load will drop below 9 volts and the keypad will
reset or
it may affect the GTO circuit itself and cause the keypad to lock
up.

We recommend that you use a large marine battery that is not a gel
cell and
hook everything up to it before powering up the GTO.
Hope this helps. Thank you for providing me with another issue to
address in
the troubleshooting section of the manual.

Marj, Astro-Physics
-----Original Message-----
From: Terry Johnson [mailto:tjohnson@c...]
Sent: Thursday, June 15, 2000 11:35 PM
To: ap-gto@egroups.com;
Subject: Re: [ap-gto] GTO Keypad Freezes Problem


Bob, I have a voltage meter attached to the battery that
displays the
battery voltage. Do you know whether a short drop in voltage caused
by
connecting an additional CCD camera and PC would to the battery
would cause
the keypad to lock-up if the keypad was already attached to teh
battery?

Thanks...Terry Johnson
----- Original Message -----
From: rck
To: ap-gto@egroups.com
Sent: Thursday, June 15, 2000 9:12 PM
Subject: Re: [ap-gto] GTO Keypad Freezes Problem


You have tested it at 12.8 volts or that is what it is
rated
to
produce?
I was getting under 12 volts when I had the problem. After I
switched
to a marine deep cycle 60AH battery, no problems--I can run
for 2-3
nights on one charge. Just the scope though, nothing else
on
it.

Regards,
Bob Kuberek


Terry Johnson wrote:

Bob, when you speak of undervoltage, when do you
consider the
voltage to be too low. My 88 amp battery with all the systems
connected puts
out 12.8 volts when the battery is fully charged to 12.2 volts
after
six
hours of usage.

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Lawrence D. Lopez <lopez@...>
 

Firstly a large deep discharge battery is the
way to go. Sam's sells deep discharge/cranking
batties (which weigh 50 #) and I have used them
for all sorts of things. Powering a home
made inverter, a trolling motor, a tractor and
finally a AP400 mount.

Of course this only works if you are a weight lifter.

Size matters.

Secondly a spike current on any battery is going
to drop the voltage.

There are three ways to get around that:

1. isolate by using a separate battery
(already mentioned).

2. Use a 12 volt DC to 120 volt AC converter.

I believe that the current crop of inverters
has a DC to DC converter followed by a DC to
AC converter. I suspect that the DC to DC
converter regulated the voltage.

With or without a 120 volt to 12 volt DC
switching converter (the type that radio shack
sells).

While somewhat less efficient you should
have very regulated voltage using this.
You should be isolated from any transient
battery effects.

Of course the 12 to 120 volt inverters
typically drop out at 10 volts.

3. An isolation diode and a big capacitor
or small battery.

The big capacitor might be one of those
things they use for car audio systems so that
the load from the audio system doesn't reset
the car computer.