1GM10 Tachometer

[Peter_spring]

Anyone know if its possible to use a car (12v) tachometer in a boat?

I would like to fit one to know the revs of my Yanmar 1GM10. Run from the Alternator, if its possible how to wire it up?

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[paulrossall]

I have a Yanmar 2GM20 and fitted a tachometer last year. Bought one at a boat jumble (new) for £35 and got the local car auto engineers to put the neccesary lead onto my alternator(Hitachi) for £5 cash. If you do a search on yanmar tachometer you will get the name of the tachometer as I have just returned from the local and cannot remember it but did make a posting on this subject last year.

<hr width=100% size=1>" there is nothing-absolutely nothing-half so much worth doing as simply messing about in boats".

 

[steve28]

i have just fitted a durite one which are available from lsuk ,mine has an hour meter and cost 60.00. the ones without the hour meter are about 10.00 cheaper.
The alternator needs a wire putting in but that takes about 20 mins to do and is simple.
the gauge is then setup via a switch on the back which is calculated with a formula that comes with the gauge.
if you get one and want any info on the setup i can help.


steve

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[Alex_Blackwood]

The Tacho needs to be connected to the "W" connection of the alternator, if you have one! If not you have to connect it to one of the alternator output phases. i.e. the a.c. output of the alternator. You can do this by connecting to the a.c. input side(anode) of any one of the diodes. It won't matter if it is an output diode or field diode as long as it is the a.c. connection!
The tacho works by frequency which is proportional to the alternator speed. Hence the need for the a.c. connection!
If you are not sure consult your local boat or auto electrical expert.
Good Luck.

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[Mudhook]

Re: Tachometer - extra wire?

My Bosch alternator has the big positive output wire and the thinner wire to the ignition warning light. It also has an unconnected wire coming out of one of the big holes. Could this be an owner-fitted rev counter feed? I don't have a rev counter at present but the alternator works just fine as it is. I can't think of anything else that this unconected wire (no plug, no terminal, just a wire) could be. Boat has no sign of any rev counter ever fitted, but a Bosch alternator is pretty certainly a retro-fit on an MD7. Any thoughts, team?
Regards, Mudhook

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[Gordonmc]

Re: Tachometer - extra wire?

This is the same set up as my alternator... agreen wire emerging from the body. It carries an AC current but when I attach it to a tacho it goes off the scale. On tickover it registers 3,000 revs with the calibration screw turned right back.

What does the panel think? could the feed wire be attached incorrectly at the alternator end, or is the tacho the wrong kit?

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[steve28]

Re: Tachometer - extra wire?

there is usually a wire inside the tacho that is soldered into a setting position for the engine, it may be a switch .
If the tacho cannot be opened up for inspection then you will need to get one that has a selector as i mentioned on other post.

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[steve28]

Re: Tachometer - extra wire?

it is possible that your wire was fitted for an alternator controller like a stirling or adverc but without opening the alternator and seeing where its been attached its difficult to say.

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[Mudhook]

Re: Tachometer - extra wire?

I don't think so Steve 28. I've just got an Adverc kit and it's clear the extra wire for that should emerge from the regulator/brush assembly. My wire comes out of one of the ventilator holes, through which you can almost see big fat coils. I have a good digital pic of this if you'd care to examine it. I will PM you a 400k file if you post here or by PM that you are prepared to accept it. Or anyone else who knows about these things.

Mudhook.

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[Jools_of_Top_Cat]

I don't think so, most car tacho's are driven off the coil rather than the alternator. There may be some, but I have never seen one.

Use a VDO or Faria which run from the alternator or fit a sensor to your flywheel which is the best but most expansive. Link to <A target="_blank" HREF=http://www.asap-supplies.com/>ASAP Supplies</A> and look up FAR32842 which I have been using for a season without a problem.

Off the alternator you need to solder a wire to one of the poles before the diodes, I can send a diagram if you wish.

For possible answers to other questions in this thread try <A target="_blank" HREF=http://www.maesco.com/products/fwm_intro/fwm_time/TAH-97026B.pdf> here</A>

Hope this helps

<hr width=100% size=1>Julian

<A target="_blank" HREF=http://www.topcatsail.co.uk>Top Cat Homepage</A>

 

[Alex_Blackwood]

Re: Tachometer - extra wire?

You really need to determine what sort of voltage you are getting from the wire.
If you have a multimeter set it on a.c. VOLTS min. 50va.c. to start with. (Some meters only have a couple of a.c. settings, one of mine has 200 and 750v a.c.)
Connect between the wire and earth you should get a steady reading of about 12 - 16 volts. irrespective of which way round the meter wires are connected.
If you get strange readings or want to double check. Set the meter on to D.C. and connect the meter common to earth and the V/ohms/amps (red or +) to the wire. If it is a.c. the reading will fluctuate +/- through 0 and in general be all over the place. D.C. will give a constant reading of about 12 - 14 volts (ish). Reversing the meter wires will result in a - sign being shown on the meter as well as the voltage.
All the above with engine running! The voltage a.c. or D.C. should be stable with any change in engine revs.
If you are happy that you have a.c. then you should be able to run a tacho. from it.
If you have any doubts then I would suggest you take the alternator to the local expert and let them do a test.


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[steve28]

Re: Tachometer - extra wire?

oh well just a thought,
mine does comes out of a ventilation hole and connects to the adverc as i didnt want to drill more holes.

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[johnt]

ummm Just one question Peter .........WHY!! if you want to fit anything i'd have thought an oil pressure guage would be far more usefull!

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[TonyBrooks]

Some cars do use alternator tachos, mainly diesel models, but I know that a Ford Granada Scorpio has one on a petrol engine - caused no end of hear ache untill I found the loose connection. Sometimes marine info cames in handy on cars.

However as the tacho is likely to be part of an instrument pannel it would require a lot of work to extract and case it.

Tony Brooks

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