I had an old tiny tach that wasn't working anymore. I bought it a long time ago and at the time didn't realize that it had an internal battery that ended up dying long before I ever got to actually use it. I used a very sharp razor knife to cut around the glued seam and opened it up. The electronics inside are all enclosed in a rubber like material that holds everything in place. After removing all of that very carefully, you'd find that there is nothing more than a circuit board, the digital readout panel and a large watch type wafer battery. It's a lithium battery with the numberBR2325 made by Ray-O-Vac. It is soldered in place. Even if you were to replace the battery it would not be feasible to remount the internals back in the case and easily reseal the plastic enclosure as well as it was originally.
It was interesting to find out what was inside however. I like to know how things work and really there isn't all that much inside the tiny tach case. That's probably why it's so inexpensive and easily replaceable. I just bought another and hope to get some running time on the engine this summer. Unfortunately that's only running time, not yet flying time. That'll come in time though. Neal Hornung lt1corve...@earthlink.net EarthLink Revolves Around You.
