Any electrical experts out there

[Mavis]

Today I asked Raymarine this question on their web site and they are usualy very good so I expect an answer tomorrow. I just wondered if anyone here could shed a light on this - On my Autohelm ST30 bi data unit the log works fine, but the depth only works intermittingly and very often shows 00 or gets stuck on a certain depth even though the actual depth would have altered. The internaly mounted transducer is clicking and the lead looks fine. Interestingly last night I noticed by trial and error using a meter on the feed that if the supply from my battery dropped below 12.5V then the unit stopped working. Whereas if the supply is above 12.5V then the unit seems to work ok.

By the way the instructions say the unit has a 10 - 13V working range.
Your help would be appriciated

 

[James_Hortop]

Using the sharp tips of your multi meter, poke them through the insulation of the pos and neg feed cable to the bi-data unit to see the actual voltage at the unit itself. You may have corrosion or broken strands in the wiring leading up to it causing a voltage drop.

Check also any fusing etc to the unit, voltage drop across corroded terminals and fuse links would be common.

Hope this helps!

James

 

[Mavis]

Hi James,
Thats what I did. I do have both the chart plotter and the bi data unit on the same feed so maybe thats something to do with it but by all accounts it should work down to 10V though I am not a sparky so looking for advice

 

[spannerman]

Raymarine told me on one of their courses that the biggest problem they have is people not using big enough cable on the supply side.
When the depth sounder is searching for the bottom it literally 'shouts' by turning up the echo signal to get a good reading, then when its established where it is it turns down the volume as it were. When its in shout mode it pulls a lot juice and this is what causes most of their problems they said. They specify 10mm cable on the C and E and G series to cope with the demands of chart, echo and radar.
So I am sure your supply or earth cable has a bad connection causing a high resistance which manifests itself when you use the depth sounder causing it to lock up.