Hour Meter not Working

[Likato]

The hour meter on my Universal M-50 instrument panel (Novatron?) stopped working, but the tachometer still works so the unit must still be receiving electricity. Anybody have any ideas as to why it is not working? Do I need a new unit? All the other gauges are working fine.

[David M]

Is it correct in assuming the hour meter is built into the tach?

Is the power to the tach the same as the power to the hour meter? If it is not then check the voltage to the hour meter. If it is the same then the hour meter broke internally and needs replacing.

If you are really in to it you can take it apart and see if it is fixable. The combination tachs and hour meters are usually press fitted and difficult to take apart without destroying it.

[Reefmagnet]

My tach is the opposite. The hourmeter works but the tach is intermittent. To cut a long story short, it's far easier to replace the whole unit.

As David M said, the darn things are difficult to disassemble and even more so to reassemble in some cases (I know, I'v tried - and it led to heartache) and usually the circuitry for both functions is all on a single PCB.

[Likato]

Yes the hour meter is built in to the tach. I do believe they work off the same power source (I'm still tracing wires). I don't think I want to replace it and I don't want to get too creative and wreck the tach. I will log hours manually for now. A new unit is $710 (!!)

[Stu Jackson]

Originally Posted by Likato

Yes the hour meter is built in to the tach. I do believe they work off the same power source (I'm still tracing wires). I don't think I want to replace it and I don't want to get too creative and wreck the tach. I will log hours manually for now. A new unit is $710 (!!)

If it's a mechanical (rolling numbers) hour meter, they sometimes get stuck, usually irreparably. Simplest solution, since your tach is still working, is to buy a separate hour meter. If your tach is working intermittently, then check all the usual suspects first (connections at the alternator come to mind...).

[model 10]

For a dependable setup use an oil pressure switch and a Hour or Hobbs meter. Maybe $75 tops.

[De_pruis]

Your problem is quite common. Here in Europe Volvo Tachometers - supplied by VDO - are breaking down quite often. A DIY repair guide can be found here: VP MD2020 tachometer repair | verl900 . Perhaps it is useful to you. Good luck!

[svinshallah]

Do a Google search for TinyTach. They make a small unit that senses the speed with a transducer that clamps on to the diesel injector tubing. Supply 12V and it works as a tach when the motor is running and an hourmeter when the engine is stopped but 12V applied. Costs about $95. Take the old tach out, cut the back off the case, put the TinyTach in a small piece of plastic that fits in the shell of the old tach.

[Ex-Calif]

Originally Posted by svinshallah

Do a Google search for TinyTach. They make a small unit that senses the speed with a transducer that clamps on to the diesel injector tubing. Supply 12V and it works as a tach when the motor is running and an hourmeter when the engine is stopped but 12V applied. Costs about $95. Take the old tach out, cut the back off the case, put the TinyTach in a small piece of plastic that fits in the shell of the old tach.

Nice tip!

Design Technology, Inc., Home of the Tiny-Tach - Diesel Tiny-Tach Tachometer