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Navman 5500 crook


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Turning herself off for say 15m, then after about  another 15m, turning back on. Power supply good and plugged in hard. Everything works good otherwise. Internal battery?

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Internal batt wont do that. Itll be power, but possibly internal. How do you know "power is good"? Youd need to be watching it with a meter at the moment of switch off, or logging it continuously to be certain. 

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3 hours ago, vic008 said:

Thanks, multimeter says she is getting power.

It does not take much of a voltage drop to make it turn off. A scope will tell you, a multimeter may not. Does the unit stay off while good power seems available? If so, as above, heat could be an issue.

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We've got a Navman 5500 sounder / fish finder that is causing issues, the depth jumps from the actual depth to a random shallow number and back, inconsistently but repeatedly. Very alarming seeing a very shallow depth flash up, until you get used to it.

We think the transducer coil has shat itself and need a new transducer. It is 'of an age'. Does that sound like the likely issue for mine, and could it explain Vic's problem, screen stays 'on', just random or no numbers.

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Does shutdown coincide with using another appliance on boat eg fridge or water pump? My navman used to shutdown every time I started the engine.

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The reason it starts back up again when the power is re supplied is due to a yellow wire (I think it was yellow) being connected to the Red power wire. This bypasses the panel switch so as the unit powers up as soon as an eternal switch/breaker is turned on.
That does not solve the problem of it turning off on it's own though. I imagine there is a cold solder joint internally. To be honest, I doubt it is worth repairing.

Fish, your unit has possibly got fouling on it's surface. The weaker signal bounces off the Keel and it gets a false shallow reading.
Too much AF paint can also do it.

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It looks like power supply quality, as IT suggested. Sometimes, when the voltage drops very slowly to a point below the digital electronics logic thresholds, they will lock up. Similarly with a quick dip.

Can you connect it to a known good battery, on its own, and see how it holds up?

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36 minutes ago, wheels said:

Fish, your unit has possibly got fouling on it's surface. The weaker signal bounces off the Keel and it gets a false shallow reading.
Too much AF paint can also do it.

Thanks Wheels, we did check that, no AF on the transducer itself. It did have barnacles on it, we were happy we thought we had fixed it - it made no difference at all...

Is it a thing that the transducer coils can get old and short / fail? The gear is fairly old. It was the first new lectronic item we installed on the boat, and we've had it for 20 yrs, so it is in the order of 18-20 yrs old now.

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I cant say never when it comes to lectronics and that fellow Murphy. But it is not a common way for them to go. Normally it is go or no go. However, if you had no AF coating on it,  then growth could once again be an issue. It only takes a week or so for any clear realestate to be snapped up by those marine invaders. You do need to put some kind of coating on the transducer. Just ensure old is removed before new applied so it does not get too thick.

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1 hour ago, Jon said:

IMHO 

You have got twice the design life out of this unit.

The easiest fix will be replacement 

Agree Jon, its just a pain in the arse drying the boat out for long enough to swap the transducers (Coppercoat, so we don't haul out ever, just clean between tides and change anodes, service prop), and the general time and boat money involved. We already have a Garmin plotter on an NMEA2k system so just need the transducer.

It did give me thought to just not use a sounder. The only time I really need one is anchoring, to know how much chain put out. All the times I've hit things or run aground, the sounder was no use anyway. Sounds don't warn of rocks that leap out infront of you... I understand the mark 1 lead line never needs firmware upgrades either...

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Not having a sounder is like not wearing your seatbelt. It can also be a navigation aid when coastal cruising. Use can use it to follow depth contours and that helps plot your position on the chart. I hate entering an unknown bay without one.

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15 hours ago, wheels said:

Not having a sounder is like not wearing your seatbelt. It can also be a navigation aid when coastal cruising. Use can use it to follow depth contours and that helps plot your position on the chart. I hate entering an unknown bay without one.

I don't think so. I would describe it more as driving around with one tail light not working. The driving with no seat belt analogy would probably better fit having no working VHF onboard, IMO. In terms of nav, I've got a chart plotter in the cockpit. I have done blind nav exercises in the past where depth is integral to establishing your position, but it is never required outside of Yachtmaster examinations. I have sufficient compasses to triangulate, and have back up GPS and charts if I have a systems failure. 

I take your point on entering unkown bays, that is a valuable use of a sounder. But right now I'm not planning on entering unknown bays. I just want to go sailing and enter my regular, well known bays. I do want to replace it, but it is a question of probably $1,000 and 2 or 3 days work (including hauling out), or I could just go sailing and be a bit more cautious. And take a lead line for checking how much chain I need out. in terms of crossing the bar, I can predict the depth as accurately as the sounder can tell me, so that is not an issue.

In saying all of that, my sounder is still working, it just flashes intermittently. I can still use it for depth and nav, at the moment. It will stop working all together soon. I just need to carry a lead line as back up I think.

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I cant agree with that fish. Your compasses are not much use  for position fixing in poor visibility - like fog, or night (unless to get a bearing on a light). The depth finder is a great source of data to help you check position. Its often an easy way to double check your GPS/plotter position... but locally, in good conditions, your probably fine.

The flashing numbers mean the unit has lost the bottom, or its too soft to get a consistent reading. Check all the wiring for pinholes in the insulation (corrosion) , and all connections for tightness and cleanliness. This issue could well be cables or connectors.

Most of the new (Throughhull) transducers are 51mm, so if that is the size of the through hull, then a new unit can likely use the same housing. New housings though have the flap that closes when you remove the transducer, so let in lots less water while changing. If you send me a pic of the transducer plug, I may have one in my 2nd hand junk you can try....

New fish finder/depth sounders start at about $600, with a transom mounted skimmer transducer.

 

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