Depth sounder woes- only working with engine on

[Eggs]

Hi,

Hoping for a bit of advice. I have a Raymarine setup running off a Raymarine E7 at chart table. My issue is with the depth sounder, works absolutely fine with the engine on, when the engine is turned off I only get a few minutes of depth, then nothing. Also works when hooked up to shore power, so I presume I have a power issue? The chap who serviced the engine last had a look and told me one of my batteries was shot, but replacing it has made no difference. I cant see that it is an issue with the main batteries as the auto helm still runs absolutely fine and that obviously draws a lot more power.

Whats the next step, check out the connections? At the transducer end it all seems to be integral, doesn't look like it comes apart? Im struggling to even figure out where the cables run, its all well hidden behind the saloon berths etc, not helped by the fact that it looks like when the previous owner upgraded everything he left all the old wiring to the previous system in place.

Any advice appreciated, whilst it works perfectly under motor it is doing my head in not having depth whilst sailing.

 

[RichardS]

What is very strange is that you get a few minutes of depth when you turn the engine off.

Is sounds as if a large capacitor might be providing power but "for a few minutes" does not seem likely.

When you say that you get "nothing" does that mean that the depth display goes completely blank or do you get zero or a few dashes or similar?

Does anything else not function when the engine and shore power are off?

I agree with you that a poor connection sounds like a likely possibility with only the alternator or charger providing sufficient power to overcome but the "few minutes" of operation is puzzling.

Richard

 

[Eggs]

Yes, that’s what I couldn’t quite work out.
I’m having a play with it now, about 60 seconds after shore power goes off it will disappear, just shows - -
Does change slightly during this time (up and down by 0.1) so isn’t just a case of showing last reading.

it also seems to be getting worse, at the end of last season I’m pretty sure I might have got 20 minutes before it went off

 

[pvb]

Are you talking about a depth readout on the E7 plotter, or on a separate instrument display?

 

[greeny]

Hi,

Hoping for a bit of advice. I have a Raymarine setup running off a Raymarine E7 at chart table. My issue is with the depth sounder, works absolutely fine with the engine on, when the engine is turned off I only get a few minutes of depth, then nothing. Also works when hooked up to shore power, so I presume I have a power issue? The chap who serviced the engine last had a look and told me one of my batteries was shot, but replacing it has made no difference. I cant see that it is an issue with the main batteries as the auto helm still runs absolutely fine and that obviously draws a lot more power.

Whats the next step, check out the connections? At the transducer end it all seems to be integral, doesn't look like it comes apart? Im struggling to even figure out where the cables run, its all well hidden behind the saloon berths etc, not helped by the fact that it looks like when the previous owner upgraded everything he left all the old wiring to the previous system in place.

Any advice appreciated, whilst it works perfectly under motor it is doing my head in not having depth whilst sailing.

Go back to basics and look at the supply.
Put a volt meter on the supply at the instrument and see what happens to it with engine on and engine off. It may give you a clue. Then go from there.

 

[Eggs]

Thanks for the suggestions. No, it’s not just an issue on the E7, it’s ok all the screens.
Update from today is that it’s definitely a power issue, only getting 10V at the transducer on shore power, drops immediately to 9.3 when shore power comes off, then trickles down to 9V over the next 60 secs or so. Does the same to the speedo/wind etc, just seems they are still able to operate at that. Checked at the batteries and they are fine, checked the main raymarine hub and it’s the same as at the transducer. Tomorrow I’m going to chase it between the battery and the raymarine hub, maybe something as simple as a corroded terminal?

 

[Eggs]

Sorry, that meant to say it happens on all the screens, not that it’s ok on them!

 

[Ammonite]

What is very strange is that you get a few minutes of depth when you turn the engine off.

Is sounds as if a large capacitor might be providing power but "for a few minutes" does not seem likely.

When you say that you get "nothing" does that mean that the depth display goes completely blank or do you get zero or a few dashes or similar?

Does anything else not function when the engine and shore power are off?

I agree with you that a poor connection sounds like a likely possibility with only the alternator or charger providing sufficient power to overcome but the "few minutes" of operation is puzzling.

Richard

Not sure why you think this is odd. If the engine is running or shore power is connected you have 14.4v or so. When you remove either source the voltage will start to fall towards 12.8v presumably triggering the low voltage cut out because there's a voltage drop in the wiring somewhere that only manifests itself without the engine or shore power.

Or it could be what you said ?

 

[PaulRainbow]

Thanks for the suggestions. No, it’s not just an issue on the E7, it’s ok all the screens.
Update from today is that it’s definitely a power issue, only getting 10V at the transducer on shore power, drops immediately to 9.3 when shore power comes off, then trickles down to 9V over the next 60 secs or so. Does the same to the speedo/wind etc, just seems they are still able to operate at that. Checked at the batteries and they are fine, checked the main raymarine hub and it’s the same as at the transducer. Tomorrow I’m going to chase it between the battery and the raymarine hub, maybe something as simple as a corroded terminal?

This is pretty certain to be a poor connection on the power supply to the Seatalk/NMEA 2000 network.

 

[RichardS]

Not sure why you think this is odd. If the engine is running or shore power is connected you have 14.4v or so. When you remove either source the voltage will start to fall towards 12.8v presumably triggering the low voltage cut out because there's a voltage drop in the wiring somewhere that only manifests itself without the engine or shore power.

Or it could be what you said ?

Indeed .... it will be exactly what I said in the very first answer i.e. a poor connection with only the alternator or charger providing sufficient power to overcome.

Richard

 

[Eggs]

Well, it took the guts of an afternoon but I eventually found the issue. The voltage drop was from the first cable out of the main seatalk box, oddly enough the cable appeared fine, looked properly connected, connectors looked good and no obvious dirt or corrosion, but in any case taking it out, giving it a good wipe and putting it back in did the trick.
At least I know a lot more about where all the wiring is now, tucked away in various crevasses and difficult to access spaces.

Many thanks for the advice!