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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.
I'd always like these Seco Mini-Prisms for a number of reasons.
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
