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Chartplotter loses fix when I start the engine???

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Chartplotter loses fix when I start the engine???

Old 11-25-2003, 03:05 PM
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Default Chartplotter loses fix when I start the engine???

My Lowrance 3000MT just started doing something strange. Every time I start the engine, it loses satellite acquistion and then reacquires. While it is not a huge deal, it is annoying when you are starting up to repeate a drift.

I'm assuming that this is electrical (duh) and related to either a drop or surge in voltage when I kick the motor over. However, the unit does not restart or cycle off and then on...just says "Acquistion Lost" and the alarm when I start up.

Thoughts? Anyone had a similar experience?
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Old 11-25-2003, 07:30 PM
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Default Chartplotter loses fix when I start the engine???

I would be assuming that the GPS module is being shutdown due to seeing a low voltage as you hit the key and the starter drops the battery voltage for an instant.

Many electronics have this brown out safety feature and if it's just starting to occur then maybe the battery is on the way out?

"Acquistion Lost" is probably a warning coming from the chartplotter itself, which might not be be set as sensitive to voltage drop as the GPS as the GPS is presumeably not simply an antenna but GPS in antenna, with separate power supply and software control.

The GPS itself is probably re-booting after the voltage drop, the chartplotter isn't affected by the drop but notices that there is no GPS signal and issues the warnings you see.

Cheers, Kerry.

I never get lost, everybody tells me where to go!
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Old 11-26-2003, 07:13 AM
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Default Chartplotter loses fix when I start the engine???

Thanks Kerry. To add further mystery, I upgraded the software in my unit recently and I can't recall whether this started happening at the same time. Also added trim tabs and so futzed with the wiring a bit, so that could have something to do with it I suppose.

Time for a little diagnostic exploration.
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Old 11-26-2003, 08:10 AM
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Default Chartplotter loses fix when I start the engine???

I've noticed the same problem with my SH150C.

I normally cruise on one battery and hold the second in reserve. I'm pretty sure my alternator cant keep up with the demand of all my electronics so if I power-off to drift for a bit. I switch to "Both" to light up the engine and then back to whichever I was using.

I recharge after each trip and alternate batteries as well.
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Old 11-26-2003, 08:52 AM
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Default Chartplotter loses fix when I start the engine???

Alex: I had a similar issue with my chartplotter loosing its fix everytime I keyed the mike on my VHF. I took my GPS and VHF connections off the fuse block and recrimped new connectors on and it fixed the problem. You may have just jostled something when you were working under the console installing the new tab controls. Sounds like you just have a loose connection somewhere.
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Old 11-26-2003, 09:38 AM
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Default Chartplotter loses fix when I start the engine???

That would be my first inclination as well, to look for loose or corroded connectors first and think about the battery itself after I had exhaused finding a connection problem.

I did find your description a bit suprising though. I just expect the entire machine to shut off in an undervolage situation rather than sort of a partial shut down.

Anyway, I'd start right at the batterys and remove, clean, and reattach the terminals, then I'd move right on up the wires all the way to the console looking at and tugging on wires. When I find myself doing this I like to take a little square of emory cloth with me and use it to clean connectors and such as I go. I tend to think of it as much as preventative maintainence as much as actually finding the problem. What I expect you will find is that when you tug a little bit on one of those wires it will pull out of a connector or that one of the screws on a switch or connector will be loose and maybe a bit corroded. You'll find it though and the fix will be easy. I might suggest that if you find the problem early on that rather than contratulate yourself and put it all back together that you go ahead and continue through the system as long as you're at it. You might just find another connection that was getting ready to annoy you as well.

Thom
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Old 11-26-2003, 10:56 AM
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Default Chartplotter loses fix when I start the engine???

Thanks Thom. I recently installed trim tabs on the boat, and after the installation I noticed that the nav lights and cockpit lights were not working. Since it was all of them I was sure it was something that I disturbed. When I hooked up the tabs, I ran them right to the unswitched pole on the buss bar, and may have jostled some stuff in the process.

As an aside, this is one of the most poorly designed aspects of my older Parker 18'. The bar is located right inside the side hatch on the console. While this is logical in terms of ease of access, it is mounted near the hatch on the very corner edge of the backside of the console tray which protudes into the area of the hatch opening. The result is that whenever you stuff anything through the hatch there is a good chance, particularly with larger soft things like PDFs and duffel bags, that it will push against either the connectors or the wires that lead to them. A very bad design decision that I hope they have changed in the newer boats.

I too was surprised that the whole unit did not cycle off, and tested it several times to confirm that was not happening. It really left me puzzled, and a little curious about how chartplotters work that current vagaries would shut down part of the unit but not the whole thing.
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Old 11-26-2003, 11:40 AM
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Default Chartplotter loses fix when I start the engine???

Based on the previous opinions, I would say the antenna is more voltage sensitive than the GPS itself.

My Garmin 2006C experiences the same condition you describe. Displays "lost communication with antenna"
Then I push the "enter" button....good to go!!
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Old 11-26-2003, 12:29 PM
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Default Chartplotter loses fix when I start the engine???

That's an interesting observation and I would never have thought of it. I had forgotten that on some machines the 'antenna' is powered separately from the display unit, and in fact in some of the then antenna is really the GPS and the display unit is just that, a display and a convienent place for memory storage.

Its just one more thing to keep in mind for the future. Thanks for bringing it up.

Thom
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