Autopilot requires warm up period.

[Antares]

A good friend has a Nordic Tug with a ComNav 1420 autopilot. When the weather is warm or if it has been used in the last day or two the autopilot functions when turned on. If it is cold out, it consistently takes 30-35 minutes after turning on to function. He has contacted ComNav service and they did not seem to interested in helping. Does anyone here have experience with this kind of a problem or have any insights?



I have a different model ComNav and have not had any issues with mine.



Thanks.

 

[bayview]

Start by removing and cleaning all wiring connections. Check battery voltage while symptoms exist.

 

[STB]

Can you clarify, what is the state of the unit during the 30-35 minutes before it begins functioning? Will it not turn on? Not responsive? Won't drive rudder indicator(s)? Won't drive pump? Etc?

It isn't uncommon for aging electronics to need a warm up time. And, it isn't uncommon for aging and failing electronics to need more of it. But, 30 minutes is excessive -- by a lot. Most things that aren't okay in a very few minutes don't magically become okay by not functioning for even longer. Even vacuum tubes didn't take 30 minutes to warm up. So, I'm actually going to bet that the problem isn't the unit, itself.

So, my first tests would be outside the box. Is the power good? All the way to the unit? Is the ground good? All the way up to the unit?

If the batteries have gotten tired or low on water, or the connections have gotten corroded and high resistance, or both, especially if wiring was too thin from the get go, it'd be really easy for the unit to get low voltage initially.

Then, as the boat warmed up, e.g. the alternators charged the batteries and voltage rises, other things pulled down from the initial start or a period of non-use get charged up and back to normal, the engines warm up the batteries, the charging warms up the batteries, etc, voltage might come up, allowing something that was threshhold before to start working.

As you can tell, my first guess is a temperature mitigated voltage issue. If all of the voltages look good, you can try opening the unit and heating it a little, gently with a hair dry on low setting and seeing if it helps. When I did electronics repair, we both heated and cooled components to try to isolate failures we couldn't reproduce the first time we looked.

But, I'm betting on voltage. Check carefully. Half checking doesn't often show results. If initially seem okay, check once initially and then again once things start working. See if the voltage at the unit (between its +12 and Neg) has changed and how they look.

Just my thinking.

 

[twistedtree]

It's hard to help without knowing a bit more about exactly what's not working. Does it not power up, i.e. the screen doesn't come alive, and it's as though it's not turned on? Or does it come alive, have operative controls, but not steer the boat?


Checking electrical connections is a good suggestion, especially if it's not even coming alive.


If it seems to work normally, but just doesn't steer the boat, I'd focus on the steering pump. This assumes it's hydraulic steering. If it's mechanical steering, I'd focus on the drive mechanism.

 

[boathealer]

The cleaning connections thing is a good first step.

In my far-too-many years in the electronics world, I saw several instances similar to this caused by cracked/broken/cold solder connections on PC boards (IC's, etc.). The connection was broken when "cold", but when power was applied and the self-heating of the device(s) would warm the system such that the expansion of the differing materials would remake the connection just by pressure. Once cold, the problem returned.

One way to test this theory if you can get at any PC boards in the system would be to gently and selectively heat areas of the board using a heat gun during the cold "warm up" period.

Just another data point.....

 

[Antares]

Thanks for the many good suggestions. I will pass these on and see if more symptoms can be provided.

 

[Antares]

Here is a little more information. When not used for a period of time and it is cold outside, the "pilot button" is pushed to engage the autopilot the indicator lights come on, however when the button is released the lights go out and the autopilot is not engaged. After the 35 minute warm up period the "pilot" button is pushed, the indcator lights come on and when released the light stays on and the autopiolt is working as expected. To me this is looking more like an issue in the processor instead of the control head.

They normally turn power off to the ap when not in use. I suggested he turn on the power early and then test at the dock to see if that makes a difference.

 

[boathealer]

Here is a little more information. When not used for a period of time and it is cold outside, the "pilot button" is pushed to engage the autopilot the indicator lights come on, however when the button is released the lights go out and the autopilot is not engaged. After the 35 minute warm up period the "pilot" button is pushed, the indcator lights come on and when released the light stays on and the autopiolt is working as expected. To me this is looking more like an issue in the processor instead of the control head.

They normally turn power off to the ap when not in use. I suggested he turn on the power early and then test at the dock to see if that makes a difference.

Sounds a lot like the microprocessor and or software is not starting up. Typically in these designs, the LED lights come on using just the electrical continuity of the switch, like the power button, and then the software powers up and keeps them alive as you release the button. If the processor with the software doesn't start up then the lights will go back off as the button is released.

This is one scenario that would support the heat-expanding connection point theory outlined above.

As an aside, be sure you are holding the power button down for 1/2 to 1 second before releasing it. Sometimes in these systems it takes awhile for the software to start up and get to the point where it can keep system alive prior to you releasing the button.