Testing for rpm output

7 posts / 0 new
Last post
Testing for rpm output

The model # I have on my boat is 6RG201OA. I would like to test this unit for RPM output to the tachometer. The tach does not work and I am not sure if it is the sending signal from the alternator or if the tach is faulty. The hour meter seems to be OK but the tach does not register at all. Any help for testing would be most appreciated. Thank you in advance for any light you can shed on my predicament

Edited by DavidC on 21 Nov 2006 - 14:23
Prestolite Electric
Arcade, NY USA
Posts - 1204


The voltage on the alternators AC terminals should be half of the alternators output voltage. AC terminal voltage is measured from the alternator AC terminal to alternator ground. Alternator output voltage measured at alternator positive and negative terminals. If you don't read this then the alternator is defective.

Good day,

Mike Windle
Not registered

My boat has a VDO tacho driven from one terminal of my 110-403 alternator. It is reading intemittently, with sometimes no rpm shown, sometimes flickering and sometimes OK. Is there an alternator fault that could explain this? Would using the other AC terminal use a different AC phase, which would allow comparison?

joe mc cool
Not registered


I have a Leece Neville alternator and it is working well. It is fitted to my old Garnder diesel engine and I would like to connect a rev counter to it to give me engine rpm.

Where can I get such an alternator and can you suggest a model. Obviously it needs to be such that I can calibrate it for use on my setup.

My alternator parts number is 859372 and the sales number is 105-330. It also has a model number with D above the number 200404.

Any suggestions greatly appreciated.


Joe Mc Cool

Bob Davies
Not registered

I have the above alternator fitted to a Yanmar 3JH4E marine diesel in place of the standard Yanmar unit. The Tachometer is not functioning correctly - the dial indicates for a few moments then fluctuates and drops back to zero. The Yanmar engineer has fitted a spare tacho which shows the same fault. We are wondering how the pulse signal from the alternator is configured? Could you supply details. Thanks.

Prestolite Electric
London, England
Posts - 203

Dear sir,

The AVi128 is a 12 pole machine supplying an ac pulse directly from 1 of the 3 stator phases (at aprox 7-8v). Have you had this problem from when you fitted the AVi128 or has this problem only resently developed? If it's occured from start of AVi128 fitment them I suspect that the original Yanmar alternator had a different no. of poles and therefore the tacho set-up is different. Please consult your tacho fitment / set-up instructions to adjust it for a 12 pole machine.

Best regards,
Jacques van Zyl

Best regards,
Jacques van Zyl


I work at a firestation that uses leece neville alternators on our fire engine, my question is what is the rated RPMs for these alternator.

the model# was non readable in the front but the back #'s are as followed. 14962PA, if you would be able to help me that would be great,



Post new comment

The content of this field is kept private and will not be shown publicly.
  • Lines and paragraphs break automatically.
  • Web page addresses and e-mail addresses turn into links automatically.

More information about formatting options

Refresh Type the characters you see in this picture. Type the characters you see in the picture; if you can't read them, submit the form and a new image will be generated. Not case sensitive.  Switch to audio verification.