I took the alternator out of the boat last weekend so I could get it tested. Any suggestions on where to take it? Would a good auto repair shop be able to do this, or do I need someone more specialized. Dave
Aries 1990 C&C 34+ New London, CT > On Oct 3, 2016, at 12:07 PM, Jerome Tauber via CnC-List > <cnc-list@cnc-list.com> wrote: > > If it's rf noise generated by the alternator it may be coming in through your > GPS antenna as well as data or power lines. If it is rf noise you should be > able to hear it with a small AM radio held nearby (tune to around 1400 KHz). > I still think your voltage regulator is suspect. When the battery reaches > its maximum charge of approximately 14.2 volts, the regulator will then limit > the alternator's output. The battery acts as a buffer so that may be what's > causing the problem to sometimes not show with the engine on.. If the > engine has been off for a while the battery voltage may fall in the 12's and > it may take a while for it to overcharge into the 14's where your chart > plotter may start to act erratically again. When you turn off the engine it > may take a few minutes for the voltage to drop back into a safe level. You > said you are measuring in the 14 volt range with the engine on. If it is > above 14.2 that would be suspect. Jerry J7J > > > -----Original Message----- > From: Della Barba, Joe via CnC-List <cnc-list@cnc-list.com> > To: 'cnc-list@cnc-list.com' <cnc-list@cnc-list.com> > Cc: Della Barba, Joe <joe.della.ba...@ssa.gov> > Sent: Mon, Oct 3, 2016 11:08 am > Subject: Re: Stus-List Chart plotter problem > > You could try something like this: > http://www.ebay.com/itm/NEWMAR-PC-25-Noise-Filter-Power-Conditioner-25-amps-/231859240381?hash=item35fbe33dbd:g:Zn0AAOSwPc9W0ftz&vxp=mtr > > Oscilloscope (scope) https://en.wikipedia.org/wiki/Oscilloscope FYI > If you know any ham radio operators, they probably know where to find one to > borrow. > > Your plotter also could just be nuts ;) > Joe > Coquina > > > From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of David > Knecht via CnC-List > Sent: Monday, October 03, 2016 09:56 > To: CnC CnC discussion list > Cc: David Knecht > Subject: Re: Stus-List Chart plotter problem > > Hi Joe and thanks for your input. Some answers below. > > Aries > 1990 C&C 34+ > New London, CT > > <image001.png> > > > On Oct 3, 2016, at 9:11 AM, Della Barba, Joe via CnC-List > <cnc-list@cnc-list.com> wrote: > > Some things to try: > 1. Run the plotter off its own battery. Little 6 ah AGM batteries are > cheap enough if you don’t have a spare battery sitting around. > Given the intermittent nature of the problem, this would be challenging to do > long enough to be definitive. I am also not sure it will identify the source > of the problem since it appears to be the power (see below). > > 2. Put a scope on the DC bus to see what, if any, AC/noise is on the > line. Include an engine start with this. > I don’t have a scope and have not used one. What kind of device would you do > this with? > > 3. Disconnect the NMEA interconnection and see what happens. > As I said, when this happened last week, the NMEA input was disconnected from > the chart plotter, so this seems to be coming from the power connection. > What is frustrating is that yesterday, I started the engine twice, once > before and once after the race, and the chart plotter behaved perfectly and > never beeped once. Nothing was obviously different?????? > > > > 4. Check the NMEA connection for configuration. Does the plotter send > and receive data or just send? No need to have the NMEA input line connected > if there is no data headed that way. > 5. Put a laptop on the NMEA connection or run the diagnostic window on > the plotter, if it has one, and read the raw NMEA stream to see if it is > getting some odd data or any data at all if it should not be. > 6. Put ferrites on all incoming wiring. > 7. Check for ground loops and NMEA isolation* > * > This one is a bit tricky. First off, make sure the power supply and ground > connections are at exactly the same place as your other electronics. Ground > loops are bit complicated to explain and hard to find, but the short version > is this step will eliminate some of them. Second is check with the > manufacturer to see if your plotter NMEA connections are true marine standard > opto-isolated. It is very possible to use direct wiring to NMEA data and not > isolate it, my laptop/plotter does just that, but optical isolation prevents > various stray voltage and ground issues from messing up the data. Equipment > is fairly resilient now, but back in the day an engine start could generate > noise that would totally screw up electronics. Even now I will start an > airplane with all radios and nav equipment off and then turn it on. I once > was delivering an airplane that had a screwy alternator I had to switch off > to use the radios and nav gear and then switch back on when the battery got > low. > BTW – my boat is wired so the engine start battery is usually separate at > engine start and has no effect at all on the electronics. They don’t combine > until charging voltage is present for a few minutes. Is yours like that? > Joe > Coquina > C&C 35 MK I > > > _______________________________________________ > > This list is supported by the generous donations of our members. If you like > what we do, please help us pay for our costs by donating. All Contributions > are greatly appreciated! > _______________________________________________ > > This list is supported by the generous donations of our members. If you like > what we do, please help us pay for our costs by donating. All Contributions > are greatly appreciated!
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