topcon gts 228

[dave2900]

I was wondering if anyone has experienced any problems with the topcon gts228. I have recently started a new job and the instrument i am using is giving me problems. When i want to set in a new station, i set up on my known point and backsight my other known point. I then come out of layout and measure my new peg using the survey measurement button. I take a reading in face left then take a reading in face right. The interesting thing is when i take my reading in face right it seems to be out by 80 or so metres in eastings. I have taken it in to the lab and the technicians can't see anything wrong with it and couldn't explain the source of the error. I showed them what happens using their targets and i also measured the distance between the targets using mlm. The distance between the targets works out to be half the distance of the eastings discrepency. Any comments would be greatly appreciated.