Yup, that's correct. If there are only two wires coming from the paddlewheel transducer, it is likely this 'generator' type as a more modern hall effect transducer will have at least three wires (I think).
Of course a broke wire or bad connection anywhere between the transducer and the instrument will cause it all to not work. We would just pull the transducer and connect it directly to the back of the instrument to see what happens. >From the Troubleshooting section (last page) of the pdf I linked: TROUBLESHOOTING DISPLAY READS ZERO- The problem could be either the transmitter or the display. Please follow the proceeding steps to determine cause of the problem- A. Measure the two wires of the transmitter with an ohm meter for resistance value of approximately 2000 ohms (2K ohms). Do not spin the paddlewheel. a. If unit is good, then check paddlewheel for any broken fins or missing magnets. b. If unit is open (infinite resistance) then unit needs replacing. B. Measure with an AC voltmeter when the paddlewheel is spinning. You should get approximately 1.0 VAC at about 5 knots of speed when unloaded (not hooked up to display). INTERMITTENT READINGS- Keep the unit wired as normal and add an AC voltmeter to where the input wires of the transmitter are connected. Motor or sail as usual- A. If an AC voltage is being produced but no speed indication appears on display, then the problem is in the display. B. If readings only occur when voltages are produced, then the paddlewheel is not always turning. Clean paddlewheel first and be sure it spins freely, and then try again. If the results are the same then paddlewheel may need replacing. On Mon, 18 May 2020 at 09:18, Josh Muckley via CnC-List < cnc-list@cnc-list.com> wrote: > So if I understand it correctly, the theory of operation for these > generator style knot meters would simply be a 2 wire system and a voltage > developed between the two? I would expect that a simple initial test would > be for continuity between the two wires with the wheel stopped. Then spin > the wheel and check for voltage proportional to the speed of the wheel. > > Josh Muckley > S/V Sea Hawk > 1989 C&C 37+ > Solomons, MD > > > > On Mon, May 18, 2020, 07:38 Joe Della Barba via CnC-List < > cnc-list@cnc-list.com> wrote: > >> There are (were) some generator knotmeters. Coquina came with one when >> we bought her. If memory serves, it topped out at 10 or 12 knots and it >> was always fun to peg it :) >> >> Joe >> >> Coquina >> >> On 5/18/2020 5:32 AM, Ken Heaton via CnC-List wrote: >> > Have you looked at this web page? This takes yo to the manuals for SR >> > Mariner Instruments (since 1973): >> > https://srinstruments.com/manuals#mariner_manuals >> > >> > The only SR Mariner Knotmeter I ever worked on (on a friend's C&C 35 >> > Mk.I 1973) was self powered. In other words, no external power was >> > needed (except for the backlight for the instrument face for night >> > use), the paddle-wheel seemed to be a generator. >> > >> > More info here: https://srinstruments.com/r/manuals/public/MANSELF.pdf >> > >> > Ken H. >> > >> >> _______________________________________________ >> >> Thanks everyone for supporting this list with your contributions. Each >> and every one is greatly appreciated. If you want to support the list - >> use PayPal to send contribution -- https://www.paypal.me/stumurray >> >> _______________________________________________ > > Thanks everyone for supporting this list with your contributions. Each > and every one is greatly appreciated. If you want to support the list - > use PayPal to send contribution -- https://www.paypal.me/stumurray > >
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