My series 2 tachometer has been dropping out on occasions, seems to go out for a few minutes then comes back up
i have been looking for the AC generator off the cam shaft but can not find it.
any ideas?

 

If your engine ignition system is fine when needle fluctuates, then it is most likely the tach itself.
You could try cleaning the (W) wires terminals at # 2 terminal of ignition SW, Tach, both side of the ballast resister and the (+) side of ignition coil.
Rgds
David

 

Thank you David, I will try that tonight

 

Terry,
If you decide to open up the tach and look for the problem inside, he are some comments from others forum members of problems areas:Quote
1. As the meter movements wear, lose their lubrication or get dirty, they require more energy to deflect the meter. Try sewing machine oil to improve the meter movement.

2. Check for cracked solder joints

3. A common failure mode is failure of the main timing capacitor C2. Failure of this cap. has caused tachs to be erratic, temperature sensitive or just plain dead. If you suspect your tach to have this problem, locate the capacitor, carefully un-solder the capacitor, and replace it with a new one. I have been occasionally able to locate a supply of 0.25uF capacitors, but available 0.22uF to 0.27uF capacitors work fine.

4. Some tachs have a failed input transistor. The germanium transistors used in the Smiths design have a very low threshold voltage. Silicon transistors have a much higher threshold voltage. It is likely that replacing the germanium transistors with silicon transistors could really change the characteristics of the tach. However, I would stick with the germanium transistors. The HEP 253 number is still a good number for finding a germanium replacement, although they are hard to find. You sure can't get them from Radio Shack anymore. There are some small electronics distributors who still do carry them. Another good part number is NTE158. Quote

Other forum members may have a favorite repair shop for Smiths Tachs, if you just want to send it out.
Rgds
David

 

I changed the capacitor and the gauge works much better, in fact it is scary steady.
i have the transistor on order from the US, I cold not find a Geranium (spelling) transistor in local electronic distributors.
thanks for the advice.
now the car is leaking oil, seems one thing after another.