Simrad Plotter Loses Position

[Durcott]

Hi Folks,
we have a Simrad CX33 plotter that has a problem. When it's working, all is fine. When it's not, all the satellite signals are lost, with no other loss of plotter function (other than the obvious loss of position /forums/images/graemlins/grin.gif ).

Antenna position seems fine, and plotter runs off 14.2 V supplied by a fixed regulator off the ship's 24 V supply. When working, signal strength indicators are more or less at maximum.

Fault condition seems random, and lasts for around 20 minutes on average. During the fault condition, we've yet to measure the supply voltage, but the spec on the unit is fairly wide.

Does anyone know of a problem, or could someone suggest a bit more debugging before we send the thing off for investigation?

Any thoughts welcome.

Thanks

Jeff Adams
for Pride of Bristol Trust

 

[rickp]

I've had this on my CX44 a couple of times - but never for 20minutes. Both times its happened, it was when it was quite lumpy and we were taking plenty of water over the top. I was able to get the GPS position back by wiggling the aerial connection on the bottom of the GPS mushroom aerial.

I've not had a reoccurance since I put some waterproof tape around the bottom of the mushroom where it screwed down onto the stub aerial - as there was a slight gap. I suspect water was getting in there and causing my problem. So far, no problems for the last 9 months or so...

Rick

 

[oldsaltoz]

Most common causes seem to be loss of or low power and antenna signal, Electrical connection / continuity would the first place to look, but with losses of 20 minutes (10 can feel like 20) you should also check the antenna signal continuity.

Talk to your local radio shop, they should be able to supply with a drop current relay, it will give a positive indication of power loss every time as the power continuity and strength are needed to hold the relay in. This will not tell you the location of the faulty connection, but it may save you having to pull the thing apart for no reason at all.

Avagoodweekend......

 

[rickp]

Hmm, I think the simrad GPS aerial is passive, not powered. Just connected to the chartplotter via a co-ax cable and nothing else....

Rick

 

[tome]

Almost all GPS antennas are powered via the coax