Socket Mobile GTOCP2 - Manual (Page 19)

19
MOUNT MAINTENANCE AND ALIGNMENT
Under normal operating conditions, minimal maintenance is required. Every 12 months the clutch knobs (4 for Dec. and 4
for R.A.) should be removed and 1 or 2 drops of light oil (3 in 1 household oil) should be put in the exposed hole. If the R.A.
and Dec. axes are attached together for a long time in outside conditions (i.e. in a permanent observatory) then the mating
surfaces should be lightly oiled or greased - if you expect to get them apart again after 10 years.
Your 1200 is a precision instrument with very accurate worm and wheel adjustments. Please be careful if you place the
mount on a flat surface, i.e. the ground or trunk of your car. The gear alignment may be affected if the R.A. and Dec.
motor/gear box assemblies sustain undue lateral force. This is true of any fine instrument. We suggest that you transport
and store the mount in a case or in a well-padded box.
TROUBLESHOOTING
Additional troubleshooting questions are in the GTO Keypad Controller manual. Please refer to them.
The LED on the GTO Control Box changes from red to yellow and the motors stop or go out completely (for
mounts shipped after 02-25-00).
1. The motors are overloaded, probably due to an unbalanced load on your mount.
Rebalance your telescope, and then press one of the N-S-E-W buttons to reset the keypad. Re-enter the last
object on your keypad and the scope will slew to the correct position. Even though your motors had stopped, the
logic in the control box retained the scope position in memory. As long as you didn’t change the pointing position of
the scope, you are still calibrated.
If the scope was moved during re-balancing, simply enter a nearby bright star on the hand controller, press GOTO
and allow the mount to finish slewing. You can then move the scope manually or with the N-S-E-W buttons to
center the star in the eyepiece, and press the #9 RECAL button. This will recalibrate the mount.
Additional explanation: The GTO drive circuit includes logic for overload protection to prevent burning out the
expensive servomotors in case of severe overload on the two axes. The primary cause is an unbalanced load in
R.A. If the extra load opposes the motor rotation, the motor must work harder to track at the sidereal rate and the
current will rise to high levels. If the current exceeds the trip point for more than a minute, the logic will shut the
motor off and tracking stops. It typically takes about 4 lb. of unbalance to trip the overload, but a very heavy load of
scopes, accessories and counterweights on the mount can decrease this unbalance threshold.
2. The voltage of your battery has probably gone below 10.5 volts.
3. The current rating of your AC-DC power supply is too low.
Additional explanation: During slewing, the two motors draw up to 3 amps from a 12 volt source. This may increase
when the temperature approaches freezing or below. It is recommended that your supply be rated at 5 amps, 12
volts DC minimum (18 volts max.). If you also power other equipment (CCD cameras, dew heaters, etc.) from the
same source, you will need a supply capable of up to 10 amps. The more equipment you have, the more current
capability you will need. For portable applications, we recommend a heavy-duty marine battery designed for deep
discharge applications. The most common problems are due to inadequate power supply.
The keypad reset (or locked up) when I plugged my CCD camera, PC (or other equipment) into the same
battery as the GTO mount was using. The battery has a meter which shows 12V.
The 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 calibrating the
GTO.
If any problems occur, please don't hesitate to contact Astro-Physics for assistance.
ASTRO-PHYSICS INC
11250 Forest Hills Road
Rockford, IL 61115
Telephone: (815)-282-1513
Fax: (815)-282-9847
[email protected]