Raymarine plotter blown-up

[devinp]

Our Raymarine plotter blew-up (returned for new powerboard) after unplugging shorepower cable. Likely problem was a resulting power spike. (BTW I don't mean it exploded!!!).

Obviously our SOP has changed to ensure that the shore power is disconnected before powering-up the nav instruments.

However I am very surprised that modern electronics are not protected from such surges (either within the shore-power electronics or the plotter). Has anybody else had a similar problem? Could it be a fault with my shore power system? The yacht is a Bavaria 34.

Regards

Phil

 

[Chris_Stannard]

It is probably the way your shore power is wired, Some systems are wired to deliver the power to the batteries and some are wired to put power onto the same circuits as your alternator. The problem with this is that there is no spike protection at all. The circuit drawings in your maklers handbook should show you how things are wired. If you read your Raymarine handbook it will tell you that the electronics should not be connected to the battery that is used for engine start.

One solution is to put in a battery just to run the electronics, though this could require considerable rewiring. If all of you instruments are Raymarine, and have been installed inaccordance with their instructions, they will all be powered from on source. If you have an autopilot this should be where the power is input, and you will know that this is the case because you have to switch the autopilot on before the instruments work. In this case powering all the instruments from a seperate battery becomes much easier. Incidentally on the power lead there should be a square black box ( a supression ferrite), which should give protection, if it is not there I suggest you get one from the local Raymarine agents

One last thought, was the engine running when you disconnected the shore power, as this could cause the problem. I would recommend you never start with shore power connected.



Chris Stannard

 

[halcyon]

Check that there's no connection between mains and the boats 12 volt dc earth. Depending on what charger you have, pos spikes should be controlled by the charger, spikes on the neg rail are less covered and can cause a spike.
What mains were on when the plug was pulled ?.


Brian

 

[Piers]

Have a word wth the maestro at Raymarine - Dave Wellcome - who is one of their main electronics development engineers, and the liason contact as Sponsor of the MBM cruise club. Tel - 02392 693 611, and dial 1614 when the auto attendant answers.

Let us know what's said.

Piers du Pré
MBM Cruising Club enthusiast
www.dupre.co.uk/fsPlaydeau.htm

 

[HaraldS]

I don't think such a fault is 'normal'or to be expected. Sure there is some possibility of a ground problem, but it might more likley fry interface circuits like NMEA pprts rather than the power PCB.

You say that it happened when you unplugged the shore power cable. Presuming that all that should do relative to the 12V circuits, is to cut off the battery charger, which would normally result in a voltage drop dowm from 14.xx to 12.xx, nothing that should bother your device.

Also the batteries that are always connected, would resist a serious increase in voltage if there was such a problem in the charger, and very short spikes would get lost in the length of wires. They only cases I know of that can induce high enogh voltages on the DC supply are lightening strikes.

Another problem are surges to lower voltages, that happen for example when cranking the emgine. Many devices have input circuitry that doesn't cut power out and back in properly and that usually leads to hanging device, when the micro processor goes out to lunch. A reset usually fixes the problem.

My best guesses are two:

1) Your plotter is connected to multiple grounds, due to DC supply, SeaTalk, maybe NMEA and maybe a GPS or DGPS antenna that is powered from the plotter, but also remotely earthed. That togther with a fault in the AC ground wireing could induce a damaging voltage accross the different grounds. Maybe worth investigating your installation further. Also in such a case, not powering up the plotter may not protect it, as the power board will be on power anyway, drawing very little, but enough to sense you pressing the power on button. Only cutting the actual may make a difference, but even that might not be enough.

2) It could be incidential. Like your plotter was going to fail anyway and the light drop in voltage just triggered it to happen. This isn't totally unlikley: Last year my Raymarine ST60 Depth instrument gave up in maybe a similar way. It had worked well the first season and has probably accumulated some 1000 hrs, so that you wouldn't think of infant mortality any more. It was then off for the whole winter and the first day back in the water, it just went dead after about 5 hours of running. Since it was out of the warranty period anyway, I opened it to find out what was going on. The problem was in the power circuitry and the part that had given up was a tiny inductance, (a coil about 1/8" long, the wires only visible with a good magnifying glass); it had become non conductive. Easy to fix, but totally unclear why it had given up, thermal tension being about the best explanation I could come up with. The sounder works fine since.

So, you may just have been unlucky.