Raymarine ST-4000+ diagnostics

[Vengeful]

Hi all,

my ST-4000+ gave me some trouble a few months ago - it was intermittently not responding to the control head. I found a loose connection in the boat-side female plug to the tiller unit, so re-connected there and it was okay for a couple days.

Now it is not responding to the control head again. I'm following the Raymarine service manual to test the tiller unit-

1. resistance at the motor is 1.2ohms (good)
2. thrust rod goes in and out by hand (good)
3. connecting to house battery through amp meter, thrust rod goes in and out and draws only about 1.1amps (good)

So, to test the head unit, i don't see much information in the manual
my first thought is: what's the output at the drive pins of the head unit when it should be driving the tiller arm - I am seeing about 10v / -10v


any opinions about where to go from here?

[GordMay]

ST4000+ Autopilots Service Manual
➥ http://www.ganssle.com/jack/st4000.pdf

[Vengeful]

Gord,

yes, that's the manual i've been following - it looks like the motor in the tiller arm passes the tests (movement, resistance, current draw).

But the manual doesn't really have any advice on what to do to test the head unit. I did notice this interesting post on the raymarine forums about a motor that tests fine not necessarily being fine.... (see post #2 below).


https://forum.raymarine.com/showthread.php?tid=7160

Originally Posted by GordMay

ST4000+ Autopilots Service Manual
➥ http://www.ganssle.com/jack/st4000.pdf

[zemurray]

have you tried taking it apart and checking for moisture inside the unit? mine was doing that after Hurricane Sally, and there was a bit of water inside. I took it completely apart and dried it thoroughly, then reassembled. No issues since. Be aware the screen, buttons, etc.. all come off the board and can get water between the layers.

[Vengeful]

Zemurray,

Thanks for the suggestion. Yes, I’ve taken the head unit completely apart and it seems physically okay. No sign of water or burned up components.. Same with the tiller arm.

Interestingly, connecting a 12v incandescent lightbulb to the head unit’s output, doesn’t light up when it would be driving the arm. Connecting an ordinary single LED, it only makes a very brief very faint flash when it would be driving the arm. Maybe possibly the head unit’s power electronics aren’t producing much current. Wish I knew a better way to test than another $400 head unit.

Originally Posted by zemurray

have you tried taking it apart and checking for moisture inside the unit? mine was doing that after Hurricane Sally, and there was a bit of water inside. I took it completely apart and dried it thoroughly, then reassembled. No issues since. Be aware the screen, buttons, etc.. all come off the board and can get water between the layers.