yamaha 30 hp trying to fit a rev counter

[xs 400]

Yamaha 30hp man start no ptt

just about to give up on this one after 2 months trying! I have posted this one before and had lot of great advice but still not managed to do it.

the issue is ..... 6 pole faria rev counter
added 12v battery

green wire from outboard to snd on rev counter
positive from battery to rev counter battery
earth from battery to rev counter, also earth from neg battery to earth on outboard.
red wire (charge positive) to positive battery.

nothing

bought multimeter ....readings red oudboard positive 6v dc tickover up to 10v dc revving
green wire 3v ac tickover to 5v revving.

The reason I need the rev counter is to find the correct prop for my boat think its Tiny tach time!

[Poly]

Originally Posted by xs 400

bought multimeter ....readings red oudboard positive 6v dc tickover up to 10v dc revving
green wire 3v ac tickover to 5v revving.

Well somethings not right there. Between the two battery terminals you should get roughly 12.5 V d.c. with the engine off. With the engine running it will rise to over 13V and potentially 14-point-something. Those voltages should be near as damn it the same at the tacho.

[9D280]

Originally Posted by xs 400

....readings red oudboard positive 6v dc tickover up to 10v dc revving
green wire 3v ac tickover to 5v revving.

What strikes me as a little suspicious there is the AC readings are exactly half the DC readings.....

I remember the big discussion but no time to dig it out & read it again today. You do have a charging kit or similar, i.e a rectifier / regulator? The tacho counts alternator pulses, not voltage, and should be plummed in on the alternator side of the rect / reg. If your regulator is gubbed or has been wired wrongly (such that one half of the AC wave is being passed through & the other totally blocked) that might explain the funny DC voltage.


Try disconnecting the red (+) between the engine & battery & see what happens. (Keep the earth or there will be no return for the tach signal)

[xs 400]

hi again, tried removing the red charge wire from outboard to positive battery .......nothing

[Davie]

Disconnect the two green wires that come from the lighting coil and put a bulb between them if this lights up it proves you have ac from the lighting coil. If this works take a red 12volt feed straight from the battery. do the same with the black for earth. If no workey your rev counter is a dud

[TrevorB]

mine is a 40Hp Yamaha manual start, so no battery

The green wires have AC on them not DC
so the frequency of the AC will increase with revs
so does the voltage and it soon popped a small 12v tail light bulb
Just reving up the engine in a water bucket so if this is a lighting coil it needs some regulating ... anyone have a current spec for it