Raymarine fluxgate or ST4000 problem

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Plevier

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My ST4000 has started behaving very erratically - large offsets from mag compass and large unpredictable jumps in the reading if you circle.
I guess it's most probably the fluxgate compass. (There is nothing metal or current carrying near it.)
Any tips please?
I have Raymarine's resistance checking values for it, will be trying that tmrw or Saturday.
Is there anything to check if you open the unit up?
Thanks.
 
There's a slender ribbon cable and an edge connector from the gimballed sensor. Other than check for damage, and good connection, I doubt there's much you can do.
Faults there would probably show in resistance checks anyway.
There always seems to be 1 or 2 on ebay, or possibly borrow one to check against.
 
Troubadour said:
My ST4000 has started behaving very erratically - large offsets from mag compass and large unpredictable jumps in the reading if you circle.
I guess it's most probably the fluxgate compass. (There is nothing metal or current carrying near it.)
Any tips please?
I have Raymarine's resistance checking values for it, will be trying that tmrw or Saturday.
Is there anything to check if you open the unit up?
Thanks.
Click to expand...

When I first fittend my fluxgate , I tried it in several locations , just sticking it on with bluetac till I found a spot that wasnt too affected by current and iron etc Might be worth trying it in different locations to see if thats whats started affecting it .
I did find that the autopilot drive motor was a big source of problems on the binnacleaffecting the Mag compass hence big separation with fluxgate ...
 
Check that the gimble pins are all correctly seated. Our fluxgate compass started to behave erratically and when we checked it the pins had fallen out. Replacing them sorted the problem out.
 
I thought it was the fluxgate as I had the symptoms you describe. I bought a replacement which was no better, then forked out for a new course computer which turned out to be the problem. Of course that also came with a new fluxgate, leaving me with 3 working fluxgates.
 
Thanks to all.
The resistances from the instrument end of cable looked iffy so I opened up the compass and took the coil assembly out. Resistances perfect measured from the ribbon cable. Cleaned with eraser, reassembled, looks promising but won't know for sure until I go out. Resistances from cable end now a bit higher than spec but balanced and stable. Hope I don't have to replace the cable installed in factory build!
 
Note I got those values pretty exactly measuring on the ribbon cable inside the unit.
Measured from the instrument end of the cable they were around 2-3 ohms higher (after I'd cleaned everything).
I believe it comes with about 9m of cable on it and mine is probably tucked behind a lining somewhere not shortened, so not unreasonable I suppose.
 
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