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Old 09-10-2019, 10:04 AM   #9
kchace
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City: Brookline, NH
Vessel Name: Shalloway
Vessel Model: Defever 44, twin Perkins
Join Date: Sep 2013
Posts: 2,260
Quote:
Originally Posted by BradC View Post
While trying to figure out why neither my FB nor Salon helm tachometers are working, I came across this capacitor that is not attached to anything. Anyone know what this is originally for and if it needs to be wired into something?

(For some reason when I attach any pic, it rotates it on it's side...)

Attachment 93799

Still haven't figured out the Tach's either...

If both tachs aren't working and they were before, its likely that either the alternator is not working or the tach feed between the alternator and the tachs has broken.

As has been stated its absolutely true that if your battery(ies) is totally charged - the alternator may not come on and this will cause the tachs to display nothing. This can especially happen if you have solar panels connected. In that case - putting a load on that battery should cause the alternator to turn on.

The alternators on a Lehman are usually set up with a field power switch that is activated by oil pressure. That pressure activated switch should have 12VDC to one side of it (all the time as long as the battery switch for that engine is on) and once there is oil pressure - apply that 12V to the other side which should then go directly to the alternator field winding. The oil pressure activated switch is pretty close to the alternator so its easy to trace.

Its also easy to tell if the alternator is working by testing the battery voltage when the engine is running. It should be at least 13+ volts unless the battery is extremely low, but even then it should come up after a little running.

If you can see the voltage rise as the engine is running, then the alternator is working and the tachs should also be working. At that point, its a problem with the wiring to the tachs. On my boat and probably most/all there is a separate power wire to the tachs which also needs to be on for them to work - and of course a return (ground).


Ken
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