Wild / Leica T2002 notes
I’ve been working with Wild / Leica T2002 electronic theodolites and thought I’d share a few notes. They were eBay purchases to support a hobby project to establish some reference points for a GNSS antenna.
In general, these older electronic theodolites seem like a good fit for projects that can’t justify a new instrument.
What I’ve found out so far:
Both the user’s manual and the service manual are available from the wild-heerbrugg.com web site (may want to email the proprietor if a given document is not yet listed; I’ve no connection to the site other than as a customer). The service manual, in particular, is essential for recovering from a dead lithium cell. The instrument constants on the paper sticker in the battery compartment can just be typed in after the cell is replaced, assuming there were no problems with or adjustments to the optomechanical “physics package”. One can also verify or re-derive these constants with a procedure described in the manual, but I haven’t done that yet.
Since the instrument has a serial port, a data collector is straightforward. I’m using a small Raspberry Pi computer ($40) with an interface to the TTL (not RS-232!) levels on the Leica serial port. A smartphone or tablet can talk to the Pi over wifi. The protocol is documented.
I have a question about the T2002 internals. How exactly is the dual-axis compensator implemented? The service manual shows it as part of the vertical-circle system, and there is just a single photodiode that somehow gives both vertical and transverse compensator values. There are cryptic drawings in the service manual involving 45-45-90 triangles etched on the circle. Presumably it’s something clever.
Also, does anyone have a copy of this document:
Katowski, O. and Salzmann, W. (1983) The angle measurement system in the Wild Theomat T-2000. Wild Heerbrugg, 10 pp.
Internet searches pull up plenty of references to this white paper, but not the paper itself. There was no response to my email to Leica requesting it.
Cheers,
Peterps: I’d like to thank Dave Ingram for his help in sorting out some of these issues.
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