Here's the scenario. 1) Old Navico autopilot 2) New Humminbird depthfinder w/ GPS receiver and shoot through transducer in the bow 3) Ritchie compass on pedestal The Navico control head had been mounted on the pedastal guard forever and worked fine (well, eccentric perhaps, but fine). The Humminbird hadn't been mounted yet, as I was playing around with transducer placement and navpad mounting ideas. I finally put everything together and sailed up to my haul out spot yesterday. On the sail (fantastic conditions for the most part) several things happened. The GPS worked fine. The compass didn't seem disturbed by the nearby electronics, though I didn't calibrate it to be sure. The depthfinder, at the dock, had started flashing between the actual depth and 1.9ft (the omg the transducer is screwed up depth). Under way, on the first half of the trip it seemed to be displaying the correct depth, and then it went to 1.9 and never came back. The autopilot, once it was actually in control and on a heading seemed to be working ok. But along the way, it too started misbehaving with two main symptoms. The Navico has a single button to switch between Set mode (idle) and Auto mode (autohelm). It also has left and right buttons for brief Dodge in either direction. At some point the Set/Auto button wasn't working correctly, either not registering a push or throwing in a Dodge. Toward the end of the trip it also seemed to be dropping out of Auto mode by itself (which I might attribute to intermittent power if not for the other keypad problem). The only change from working to frazzled is 1) mounting on a pad at the pedestal guard, bringing the instruments into proximity with each other and with the compass and 2) running the power and transducer cables side by side in a long run. So the question is (long winded as it is), do you think either of these factors could account for the weird instrument behavior? Or is it maybe just a massive coincidence? (The autopilot glitches were independent of the on/off state of the GPS/depth unit)
Scrambled electronic eggs
- Thread starter T37 Phil
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Possible voltage issue?
I may be way off base here but is it possible that the voltage may have gone down enough on your battery bank to cause erratic behavior? Any high draw items turned on right before you started having problems? Conversely, could you have had a spike in your electrical system? Did you happen to start the motor just before? I've noticed I get erratic behavior from my knot and depth meters if I crank up the old diesel while the insturments are on. I generally have to power-cycle them to get them to read accurately again. Manny
I may be way off base here but is it possible that the voltage may have gone down enough on your battery bank to cause erratic behavior? Any high draw items turned on right before you started having problems? Conversely, could you have had a spike in your electrical system? Did you happen to start the motor just before? I've noticed I get erratic behavior from my knot and depth meters if I crank up the old diesel while the insturments are on. I generally have to power-cycle them to get them to read accurately again. Manny
Check connections
I think Manny may have a point. Electrical connections can develop corrosion which will cause high resistance resulting in lower current which can cause electronics to perform erratically. Check the connections or redo them. The erratic depth readings on a shoot-thru transducer can also be caused by incomplete adhesion of the transducer to the hull. A bubble or two can confuse the unit.
I think Manny may have a point. Electrical connections can develop corrosion which will cause high resistance resulting in lower current which can cause electronics to perform erratically. Check the connections or redo them. The erratic depth readings on a shoot-thru transducer can also be caused by incomplete adhesion of the transducer to the hull. A bubble or two can confuse the unit.
Still confused
Batteries strong. All units were powered off and back on with the same problems. The depthfinder is new, so not expecting corrosion problem there, but the autopilot connection is worth a check. I suspected a transducer bubble too, it's the same behavior I had when testing it in a bag of water and I lost the water. However, it's glassed in now and it *was* working great. I'm not sure how a bubble could have developed over weeks. Really the only thing that changed recently was cable routing and mounting the display/control units.
Batteries strong. All units were powered off and back on with the same problems. The depthfinder is new, so not expecting corrosion problem there, but the autopilot connection is worth a check. I suspected a transducer bubble too, it's the same behavior I had when testing it in a bag of water and I lost the water. However, it's glassed in now and it *was* working great. I'm not sure how a bubble could have developed over weeks. Really the only thing that changed recently was cable routing and mounting the display/control units.
No joy, or maybe partial joy
Went back to work on the problem today. The autopilot appears to work, at least at the dock. The Set/Auto mode button toggles nicely between modes. If I set the heading and switch to Auto, the motor doesn't turn circles. If I change the heading slightly, the motor adjusts the rudder to try and make the new heading. The poor thing doesn't understand that we aren't moving. This weekend I hope to have time to test it for real. In the process of moving it around the past few weeks it may have spent some time upside down. Maybe it just needed to reorient. The depthfinder is another issue. I routed the power cables separately from the transducer cables. I removed the display head from the pedestal. Still no depth reading. That leaves the cable integrity (bending caused open during installation?) and the transducer. I can take out the extension cable this weekend and rig a power cable to reach at that location. If that doesn't work, it's either a bad transducer, or the in-hull mounting failed. The display head isn't reading "No transducer", so I don't expect there is a problem there. How do you remove a transducer without damaging it once it's glassed in? Is there a pin test with a multimeter that can be done on the transducer before trying to pry it out? While I'm at it, I can check for an open in the extension cable.
Went back to work on the problem today. The autopilot appears to work, at least at the dock. The Set/Auto mode button toggles nicely between modes. If I set the heading and switch to Auto, the motor doesn't turn circles. If I change the heading slightly, the motor adjusts the rudder to try and make the new heading. The poor thing doesn't understand that we aren't moving. This weekend I hope to have time to test it for real. In the process of moving it around the past few weeks it may have spent some time upside down. Maybe it just needed to reorient. The depthfinder is another issue. I routed the power cables separately from the transducer cables. I removed the display head from the pedestal. Still no depth reading. That leaves the cable integrity (bending caused open during installation?) and the transducer. I can take out the extension cable this weekend and rig a power cable to reach at that location. If that doesn't work, it's either a bad transducer, or the in-hull mounting failed. The display head isn't reading "No transducer", so I don't expect there is a problem there. How do you remove a transducer without damaging it once it's glassed in? Is there a pin test with a multimeter that can be done on the transducer before trying to pry it out? While I'm at it, I can check for an open in the extension cable.
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