| Electronics > Beginners |
| 6V EDC cable not powering theodolite |
| (1/1) |
| rinconpaul:
[/img]I have a question in regard charging cable. I bought an old theodolite (20+ yrs old) The charger is stuffed. The theodolite has a 3 pin 6volt socket for external power input. The charger cable with the male plug to suit the 6V power input socket has a black, red and blue wire. I soldered two cables to the black and red and attached via alligator clips to a 6V lead acid battery. Unfortunately it won’t power the theodolite. There was one battery that came with the theodolite that carried a charge, so I know the theodolite works. What is the 3rd wire for and how do I get it the theodolite to accept an external power source? Cheers |
| Yansi:
What does an old theodolite need power for? |
| amyk:
1. Make sure you get the polarity correct --- never trust the colours. 2. A "6V" lead acid battery is closer to 7V fully charged. Check how that third connection is wired on the original battery; it could be a lower-voltage tap to supply some other circuitry, or a "presence" signal, or a thermistor, or something else entirely like a custom DRM chip/1-wire EEPROM (although I'm not sure if that was so common 20 years ago.) |
| Jwillis:
First guess would be a temperature sensor.Second guess is a communication wire for charge balancing .Third guess is a battery gas gauge.Without knowing the product it difficult to tell. |
| Jwillis:
--- Quote from: Yansi on September 02, 2019, 09:09:13 pm ---What does an old theodolite need power for? --- End quote --- Some have self levelling ,inclination sensors and digital readouts. |
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