tach Problems

[Bass Addict]

My tahcometer quit working last year so I replaced the gauge. Still doesnt work, I checked 12 volt source and ground. Good. I checked the pulses (AC) with multimeter and its good. Does anyone have an idea?

 

[jon the fisherman]

usually, that is the voltage regulator gone bad

 

[Bass Addict]

I checked the voltage and its charging 13.4 volts, I have 10.3 volts on the sensor pole and run a ground straight to the battery. Still doesnt work ????????
New tach head ????????????????? If the voltage regulator was bad it wouldnt charge or over charge wouldnt it ??????????? I'm stumped???????????

 

[SNUFFY]

You`d think they could come up with a simpler way to measure RPM.
On an OMC I believe it uses the rectifier somehow for the job. Don`t know what they use on anything else. And the rectifier may tied to the volatge regulator...don`t really know.
I installed one on an older boat I had and there was a place on the back of the tach to set the number of cylinders. My OMC 225 will read any where from 2k-10k at WOT...then sometimes it will read right at 6200 .I believe a rectifier costs 6-700$ and it doesen`t seem to have any other problems...so I`m just gonna read whatever it says.
Sounds like your getting the right signals though !
Maybe Bubbakat can offer something !

 

[Bubbakat]

I know on the older type of motors, you know before all the electronic hoop laa came along, about 8 to 200 you need to hook that tach to and unregulated power supply from your motor and ground it back to your motor and it would work. What kind of motor are you trying to get your tach to working on?


Snuffy on your s giving eratic readings you need to get a 2000 ohm resistor that reads one way and hook it to you sensor wire and to the ground wire and it will stop the charge loop that is taking place so yours can get a correct reading.
On the water cooled recetfier that they put on those omc and mercs that cost 400 to 800 bucks to replace can be replaced with a bridge recetfier from radio shack for less then 5 bucks.

 

[SNUFFY]

I knew you`d know something helpful.
$5 instead of $400-800 is good to know ...that thing leaks a little till it warms then seals up anyway.
Thanks BKat !

 

[Bass Addict]

Its a 1991 Johnson GT 200.