Help testing my old autopilot

[Joe Myerson]

My vintage (1982) Cape Dory 25-D came with an equally vintage autopilot, a Navico TP-1600. The previous owner told me he used the unit (only when under power), but I've never been able to get it to work.

Last year I tried to use it, but couldn't. Somebody suggested I replace the fuses--and sure enough, the fuse in the unit was fried. I replaced that, and it still didn't work. I thought power might not be getting to the cockpit plug, so I reconnected the wires. But the thing still didn't work.

Right now the boat's out of the water, under shrink-wrap, and the batteries are out of the boat. So my question is, does anybody know of a way that I can check to see if the unit does work while it's sitting in my basement?

Please be advised that I know very little about marine electrical systems, so any responses should be couched in terms that a total novice could understand.

Thanks everybody,

--Joe

[Jim Davis]

How about hooking it up to one of your batteries and turning it on. You can then turn left and right while holding it in your hands and see if the arm extends and retracts.

[Joe Myerson]

Jim,

Do I have to worry about which wire from the battery goes to which end of the autopilot's plug? (See what I mean about not knowing much about this 12-volt, DC stuff.)

[Neil Gordon]

Do I have to worry about which wire from the battery goes to which end of the autopilot's plug?

Yes! (Okay, yes, it matters. It's up to you whether you worry about it.)

[John D.]

Do I have to worry about which wire from the battery goes to which end . . .

I think DC electric devices (motors, solenoids, etc.) respond differently to reversed polarity than electronics (circuit boards).

The ram would just run backwards, but I think the control circuit board would not work at all, and might get fried. I don't know whether a fluxgate compass is electric or electronic.

Any electrical engineers out there?

[mahalocd36]

Any electrical engineers out there?

Yes!

My best guess would be that polarity IS important. My semi-educated opinion is get a copy of the owners manual and check the color code. Lacking a manual my first guess would be if you have a black and red wire the red wire is positive and the black wire is negative. Have you tried searching online for an owners manual? If all else fails you might try taking it apart, sometimes the circuit board will be marked where the wires connect.

BTW this is Rich not Melissa

[mahalocd36]

http://www.simradusa.com/1-manuals.php

Brown is positive
Blue is negative

[Joe Myerson]

n/m

[Oswego John]

Hi Joe,

Two things. You probably have/should have a diode(s) in the circuit(s) to prevent reverse polarity. The diode(s) allow current flow when hooked up with the correct polarity. They prevent current flow when hooked up in the incorrect, or reverse polarity. It could be considered an electric check valve.

You mention that you replaced a blown fuse. Have you done anything to correct the reason that caused the original fuse to blow? Perhaps the "new" fuse is also blown again.

Good luck.
Think spring,

O J

[Doug Fallin]

Joe,
I too have an old Navico TP1600. It works well while motoring, but shouldn't be used under sail. It responds too slow. I use mine to keep course while setting and dropping sails. IT DOES MATTER which way you connect the power. It will blow the fuse if reversed. Get the correct fuse too. I'm not sure, but I think its a 5A fuse. Anything less that what you are suppose to have will blow. I tried a 1A once when I was out of 5A, and it blew within a few seconds. Keep plenty of extras aboard. I believe you can still download the owners manual from Simrad (Simrad.com). I took mine apart, greased the shaft to quiet it down some. Internally, it is a simple design. Good luck with your unit.