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Using old hand me down equipment strikes again...I have been occasionally losing lock for no good reason at all while other times it works amazing.?ÿ
I noticed some weird stuff inside the original Leica grz4 360 prism.... hopefully it shows up in the picture.
Today it went into a fit where it would lose and regain lock over and over without me moving. I rotated the prism 180 and the issue went away. If the weird discoloration is facing the instrument it's not happy. I switched back to my Sokkia ATP1 360 prism and all is well (except for being 1.8mm off of the prism constant).?ÿ
I should really gave a regular round prism for backsights and high precision stuff and a 360 for my typical construction layout.?ÿ
Any suggestions?
?ÿEdit:
Forgot to post the pics. I assume I'm not supposed to see anything weird like that inside the prism.
Leica precision 360?
Hard to tell from pictures but wondering if you are referring to a blackening in the back of prism? Copper coating at back corroding my guess.
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In any case since you do mostly layout I'd be getting a gmp101 for several reasons, better centring error, lighter on pole, don't have to remember which face to point to instrument to avoid 5mm height error and far cheaper.
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A geomax version of the grz4 you have came with my Zoom90 and I've yet to use it. Done all my topo, setout and boundary work with gmp101. I find it easy enough to keep pointed at instrument and before I reach down to set a point I cover prism with my hand and then lay it down, then once point set when I stand pole up to get check it locks on again without searching for it.
That makes sense. Covering the prism keeps the instrument from turning and trying to follow the prism.?ÿ
I always use a bipod so I don't have to lay the pole down at all. The Sokkia robots I used before would never pick up lock again like that so I got to the point of never wanting to lose lock.?ÿ
Oh and it's not really a blackening. It's a weird discoloration on the inside and you can see what looks like glue in others. I feel like maybe glue leaked out for some reason. I can't properly catch it with the camera.?ÿ
360?ø prisms of that type are just 6 small prisms glued together. What you are seeing is the glue separating. A new 360?ø prism will run you $1000, maybe more.?ÿ?ÿ
As?ÿ far as loosing lock - it is likely that your problem is being caused by the sun. With the sun at your back, the instrument is seeing it through the prism ... and it doesn't like that.?ÿ
I definitely had issues more often in bright sun low in the sky, but it definitely seems happier overall when I use the newer Sokkia 360 prism.?ÿ