Topcon GTS 800 series robotic vertical trouble
I have a Topcon GTS805 robotic. It was recently discovered that the verticals shot for topo were randomly reading low from o.03' to 0.6' Highly embarrassing to say the least. I'm wondering if anyone else has had this issue, and if so, what was the remedy ? I'm afraid to use this instrument until this can be resolved.
Topcon want me to check everything (insinuating operator error) before I send it to a topcon shop. Unless I've gone completely mad, I think I've taken the shots in a proper manor. I use Parani bluetooth with the unit and always wait for the display to register "Good" connection before accepting the shot. Cross checks to previous control were three hundreths to five hundreths, so everything seemed great. Horizontal positions checked fine as well.
Stumped by the robot
My suggestion is that you first manually collimate a prism, or any target which would give you a precise reference for the vertical. Do this manually. Record the face one reading, then reverse face and collimate the same target in that orientation.
Compare the face 1/face 2 readings. They should sum to very nearly 360°. Whatever amount they are different, either more, or less than 360° is twice your vertical circle error. If there is no correlation between the vertical area and distance, as in the error is greater the greater the length of the measurement, then there is more to look at, since your statement of what is happening seems to suggest that the error is random.
The compensation range of most Topcon Robots is +/- 6 minutes on the vertical. If there is a fairly significant difference between the face 1/face 2 vertical circle readings and 360°, say 4 minutes, meaning your vertical circle 0° point (straight up) is out 2 minutes. At 200 feet, 2 minutes of vertical circle error amounts to an error of about 0.175 feet. At 400 feet, it would be about 0.35 feet.
To remedy this, you go through a procedure that is outlined specifically in your operator's manual.
It is described on pages 9-10 & 9-11.
If you do not have the manual, I can send you a pdf of it.
Thank you for the follow up. Glad it helped to eliminate an issue for you.
For what it is worth, the collimation adjustment that you went through to eliminate this maladjustment is something that you should do routinely. Some say, daily. Others say do not do the collimation routine to adjust the vertical 0° reference point unless it needs to be done. But even then, you cannot know whether it needs adjustment unless you compare face 1/face 2 vertical circle reading on a precise reference if you do not check it regularly.
Lest it seem that a properly handled instrument should stay in adjustment, remember that reading to 1" discretion on angular display is dividing the 360° circle in 1 in 1,296,000 parts on a glass circle that somewhere between 7-8 cm in diameter. Even appropriate routine handling of the instrument and temperature fluctuation can account for the changes in collimation alignment that makes adjustment needed.
Hi Jerry. As you may have noticed on a new tgread, this food in is now having issues shooting distances during remote controlled survey. I've been told it needs a CAL adjustment ? Since I don't have a manual,I wonder if this procedure can be found on line.
poor old instrument has been around for a while.