I recently reacquired the old GTS-3b that my father purchased new in the mid-80's. The manual is missing, and I'm hoping someone here has a PDF manual. A 10+ year old thread has a link to one but it's invalid. I'm also looking for an external 12v battery adapter. It'll rarely get used and I don't want to spend the money on new batteries.
By the way, you don’t need a genuine Topcon external power adapter (e.g. the AC-5). Get a DC buck converter from Amazon (see the example linked below), some wire, and the appropriate size coaxial power plug to mate with the GTS-3B’s external power socket, and you’re good to go. I recommend converters that have a screwdriver adjustment of their output voltage, versus an easily changed knob, so as to reduce the risk of frying your total station.
Hmm, a couple of different attempts to include an Amazon link have not worked. Here’s a screen shot of the product listing:
I have re-celled handle batteries for my GTS-303b, and the 3b batteries should be much the same. Some wires have to be soldered, but the process is not all that difficult or expensive. You just need six C-size NiCads, available at Batteries Plus. If you have the original charger, you might find a re-celled handle battery more convenient than hauling around a 12-volt battery plus an adapter.