Early 90 hp Yamaha tachometer wiring diagram

[circlehook]

 

[circlehook]

Does anyone know what screws are the power 12v, trigger screw, & ground screw

 

[circlehook]

Does anyone know what screws are the trigger, ground, and power screws it’s a early Yamaha tachometer
Thanks bob

 

[Bondo]

Ayuh,..... I'm Guessin' the 12/ B is 12 volts, battery, 'n the G is ground, which would mean the 4 is for the trigger wire,.....

 

[dwco5051]

Looks to me like the jumper is from b to 12 pole, it would be switched over for a 4 pole. That leave the two in the top center for +12v and the other for signal. Hook the G to -12v and touch one of the top two to +12v. If the needle jumps to zero that is the power. If not try the other. The instrument light is separate.

 

[circlehook]

So is “b” for power, “4” is for trigger, “g” is for ground does that sound correct

 

[dwco5051]

So is “b” for power, “4” is for trigger, “g” is for ground does that sound correct

No. The jumper bar between b and (12 or 4) is to set the number of pulses expected from the alternator. the two in the top-center are trigger (usually marked with a S for signal) and positive power usually sent from the ignition key switch. The G is negative from the battery. The power from the ignition switch should be purple, the negative would be black, and the signal from the motor gray if wired my marine mfgs code. It was more than likely made for different engines with smaller ones only having 4 pulse alternators and the larger ones 12 pulses.

 

[circlehook]

So then “b” doesn’t get a wire, “g” is ground, and the (2) top center are the positive & trigger. I will try that.

 

[circlehook]

Oh it came off a early 90 hp Yamaha, and I would like to see if I can get it to work on my 1980 135hp Mercury

 

[dwco5051]

Oh it came off a early 90 hp Yamaha, and I would like to see if I can get it to work on my 1980 135hp Mercury

Should work as it is since your Merc is a 12 pulse. Here is a listing on what the output is for various motors. https://fariabeede.com/site_manuals/IS0012_A.pdf

 

[circlehook]

I tried this and also reversed the trigger/
Gray lead and the 12v red lead both ways and nothing the black lead was ground

 

[circlehook]

I know there is a Signal I called CDI Electronics and they said to use a DVA meter and from the gray/Signal wire & ground I should have 8-20 volts I had 11.9 so the signal is there I am just not hooking the tachometer correctly

 

[dwco5051]

Next step, try red to "B" on tach and see if the needle moves to zero. Then there are the top two left to find which is signal.

 

[sam am I]

Shot gunning where the wires might go is risky, might have fired something already by reversing polarity and such ..........Can you open the unit up (spin off a few nuts) and take some decent pics of the insides?, e.g., wiring points, printed circuit board, trace side, component side and such?