Land Surveyor Forum

Hi, 

I am a budding surveying professional and am trying to troubleshoot my old Nikon DTM A20lg total station. Currently riding the struggle bus as the original manual is pretty slim and not comprehensive. Most of my work is in water resource sciences, performing topographic and bathymetric surveys for river engineeirng projects.

I'm only trying to use this (old, inexpensive) TS for simple local surveys in very rugged, WET, accident prone locations, thus why I have gone with the obsolete, vintage tool. I do not have a data collector. Really just trying to get local coordinates and topographic survey scratched into a notepad and put into CAD/HEC.

I have poured through the manual and have figured out how to reset the horizontal reference angle (zenith) to 0 degrees for a local survey and set the XYZ of the TS origin/station point to 1000,1000,100. I input target height & instrument height no problem. Sokkia prism constant is set to 0mm. 

My problems arise when I shoot the prism for topo shots. When I sight the prism and take a shot, it goes through the motions with the EDM (I can hear it whirring), but it doesn't spit out the horizontal distance (HD), vertical distance (VD), or calculated XYZ coordinates of the ground shot. Instead, the output reads that the prism/target is located on the station point (1000,1000,100.83 - that extra 0.83 is weird). This happens regardless of where I move the target. When I check the measured distances of a shot using the keyboard buttons, it reads the slope distance (SD) - which appears to be accurate - but a horizontal distance (HD) of 0. Vertical and horizontal angles (VR, HR) appear to be consistent and accurate when I re-position the target back on the same ground shots.

Whats weird is it is calcuating the slope distance but not registering any horizontal or vertical distance. The slope distance appears accurate when I pull a tape from the EDM to the prism. 

Other forums have suggested trying longer and shorter distances for ground shots, rebooting, re-set initial settings, pulling the batteries and letting the unit sit overnight, then trying again. Nothing changes.

I'm going to send it in for calibration (been stored 10 years) and service, but wanted to see if folks know of anything else I should try. Its a fun little unit - when it works! The last time I know it worked well was 2 winters ago.. 

Thanks