Newbie here. You guys helped me out earlier in tracking down a user manual for an old Nikon C-100 total station that I just picked up, and now I'm hoping I didn't get a lemon.
Got it all set up and have been attempting to test it out with a brand new triple prism, but even when set up indoors and about 20' away, I can never get it to display a distance. If I switch to an averaging mode, I can get it to display a "Low-Signal" message when I pan off of the prism, so it seems like it's receiving a bounced back signal (and looking in the optics I can see the red laser diode illuminated).
Am I overlooking something simple? Is this kind of an error indicative of something in particular? Before I attempt to get my money back (it was listed in excellent condition), I thought I should check with the experts. Thanks in advance for any help you can provide!
Take it outside and try a reasonable distance. Old edm's had issues with short distances.
vern, post: 384922, member: 3436 wrote: Take it outside and try a reasonable distance. Old edm's had issues with short distances.
Thanks for the quick reply. I just set it up again outside, and tried shooting a distance 50' away. No difference--still just displays 0.000' for all measurements.
slyck, post: 384930, member: 11966 wrote: Thanks for the quick reply. I just set it up again outside, and tried shooting a distance 50' away. No difference--still just displays 0.000' for all measurements.
Have you tried rotating the scope through a full vertical revolution. Sometimes Zenith angles don't read corectly until the vertical circle is indexed. This could mess with a horizontal distance.
bobwesterman, post: 384933, member: 7106 wrote: Have you tried rotating the scope through a full vertical revolution. Sometimes Zenith angles don't read corectly until the vertical circle is indexed. This could mess with a horizontal distance.
Yes, I've done that. Both the vertical and horizontal angles read out properly and update as they should, but both horizontal and vertical distance stay stuck on 0.000' (and slope distance, if I toggle modes). When I pan onto the prism, I can hear the faint sound of the stepper motor inside, so I assume that it is at least recognizing that there's a reflected signal present.
I was thinking that maybe the edm "beam" had become misaligned (not coincident with the line of sight). Doe the stepper motor activity indicate it is aligned, more or less?
BajaOR, post: 384937, member: 9139 wrote: I was thinking that maybe the edm "beam" had become misaligned (not coincident with the line of sight). Doe the stepper motor activity indicate it is aligned, more or less?
It seems to be (at least as far as I can tell). When I was shooting from 20-30' away, it would "miss" the prisms if I aimed in between two of the three prisms, then I would hear stepper activity if I swung it back on to one of the three prisms. In fact, when I was shooting indoors, I tried it in low light, and I could even see the beam through the telescope, reflected in the prism.
My only thought so far (for something that could be broken), is if the stepper motor within the EDM is actually functioning properly. I can hear activity, but without knowing exactly what the inner workings are of an EDM like this, is it possible that motor is bound up, or somehow not articulating whatever it needs to fully?
You may not want to open it up...but, on my D-50; there is a mirror inside the scope that had gotten foggy. I cleaned the mirror and it fixed it.
So, I shined a light in the scope and don't see anything noticeably foggy or broken. I've attached a photo in case anyone sees anything different. Also, I can see the component that is rotating--not sure exactly what its function is, but it looks like a clear plastic disc--almost like an optical encoder or polarizer. Whenever the prism is moved into the path of the scope, that little disc starts moving (back and forth, almost like a camera trying to auto-focus). It does look like there may be some dust on it--maybe that's a problem?
[MEDIA=youtube]pa0zUi8iJzA[/MEDIA]
I haven't used Nikons for 15 years. I use to swear by them, they worked good as gold.
From my memory when the "edm" went kaput, the display read an error code. If you are reading a distance of zero, I'm gonna bet your IR tube is good. If you're getting a display without an error code, your mother board is probably good. Now I'm going to let the Scotch talk for a while.
Distances are determined by timing the infra-red signal from its emission until it is reflected and sensed. This is done actually by measuring the elapse time. I'm betting there is an internal battery on your mother board that is strictly for clocking the signal...and its shot. Anything else in my mind would return an error code on the display. Check with someone that can tell you if there is an internal battery on the mother board. Scotch out...
I don't know nuffin about it. Except, that I have managed to fix stuff. And, I have managed to get things apart permanently before!
paden cash, post: 385273, member: 20 wrote: This is done actually by measuring the elapse time.
I'm under the impression that IR guns -- especially old ones -- do a phase comparison between the signal from the prism and one reflected inside the gun via split prism. I thought that only lasers -- and only some of them -- calculate distance via time-of-flight.
But I don't know squat about Nikons, so maybe they're different.
Jim Frame, post: 385280, member: 10 wrote: I'm under the impression that IR guns -- especially old ones -- do a phase comparison between the signal from the prism and one reflected inside the gun via split prism. I thought that only lasers -- and only some of them -- calculate distance via time-of-flight.
But I don't know squat about Nikons, so maybe they're different.
I don't know squat either, just wondering out loud. Those things throw so may error codes up on the screen when they don't feel well I think it odd that it reads zero...hmmm...maybe we'll find out.
paden cash, post: 385273, member: 20 wrote: I haven't used Nikons for 15 years. I use to swear by them, they worked good as gold.
From my memory when the "edm" went kaput, the display read an error code. If you are reading a distance of zero, I'm gonna bet your IR tube is good. If you're getting a display without an error code, your mother board is probably good. Now I'm going to let the Scotch talk for a while.
Distances are determined by timing the infra-red signal from its emission until it is reflected and sensed. This is done actually by measuring the elapse time. I'm betting there is an internal battery on your mother board that is strictly for clocking the signal...and its shot. Anything else in my mind would return an error code on the display. Check with someone that can tell you if there is an internal battery on the mother board. Scotch out...
Hey, you can let the Scotch talk anytime you want! Following your thoughts, I did pull all of the covers off to expose the electronics. However, I can't identify any board-mount battery anywhere. As you said in a later reply, with as eager as these old stations are to throw errors, I'd think something like a dead on-board battery would be something its internal diagnostics would catch.
Jim Frame, post: 385280, member: 10 wrote: I'm under the impression that IR guns -- especially old ones -- do a phase comparison between the signal from the prism and one reflected inside the gun via split prism. I thought that only lasers -- and only some of them -- calculate distance via time-of-flight.
But I don't know squat about Nikons, so maybe they're different.
This could make sense. Is it possible that the rotating plastic disc is some kind of diffraction grating that is modulating the phase as it rotates? This is so frustrating to me, as I just lack in-depth knowledge of the functional components in this type of total station. I'm an electrical engineer by degree, so there's at least a chance that I could troubleshoot and potentially fix the issue, if I just understood the detailed principle of operation.
Found this image (Pentax, not Nikon)--I'm assuming that what I'm seeing move is the filter noted on the left side? 
Nikon C-100
http://www.ebay.com/itm/Nikon-C-100-Total-Station-/391524966439?hash=item5b28b4e027:g:R~wAAOSwZVlXo-ax
Nikon NPL 350 Prsimless:
http://www.ebay.com/itm/Nikon-NPL-350-Prismless-Total-Station-/222208924937?hash=item33bcaf1d09:g:B1YAAOSwnQhXoo~D
And, if you don't mind topcon, these are good guns.
http://www.ebay.com/itm/TOPCON-GTS-3-TOTAL-STATION-TRANSIT-/271887060616?hash=item3f4dbb4e88:m:m1yn8HDIjDvxPlSjt5voeWQ
slyck, post: 385348, member: 11966 wrote: I'm an electrical engineer by degree, so there's at least a chance that I could troubleshoot and potentially fix the issue, if I just understood the detailed principle of operation.
That does make a world of difference. Since you're a double E maybe we should start by asking if you've removed the lens cover?
Slyck - please don't take this personal,,it's just my dark sense of humor and the level of love and affection I have developed over the years for engineers...
laugh with us buddy! 😉
paden cash, post: 385416, member: 20 wrote: That does make a world of difference. Since you're a double E maybe we should start by asking if you've removed the lens cover?
Slyck - please don't take this personal,,it's just my dark sense of humor and the level of love and affection I have developed over the years for engineers...
laugh with us buddy! 😉
Maybe that's the issue! It seemed rather dim so I tried pointing it at the sun for a while...:D
slyck, post: 385419, member: 11966 wrote: Maybe that's the issue! It seemed rather dim so I tried pointing it at the sun for a while...:D
Seriously I can appreciate your confidence level to get in there and fix it. From my experience it is a whole lot easier to send them to the shop. That is such a unique circumstance that I can't help but think there's a good bench tech that might have some insight. The trick is finding one that has experience on your particular model. Good luck and keep us informed.