Raymarine ST7000 & Linear drive

concentrik

concentrik

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Can't get a response from Raymarine so thought I'd try here over the weekend.....

ST7000 + Type 2 Linear drive (ram) + Type 300 controller.

The old ram was sticking and RM said it needed new thrust bearing, planet gears, so I bought a complete ram secondhand.

This ram extends and retracts when connected to 12v.

Installed in the system however it doesn't work. Here's the sequence. The boat is moored:

1. Turn system on - display shows breifly "ST7000" then defaults to"STANDBY". ok so far.

2. Select AUTO. "AUTO" appears on the display. ok so far.

3. Call for ten degree turn by pressing +10. At this point the ram twitches, the display flashes "ST7000" and reverts to "STANDBY".

It happens every time. It's not the motor, I've swapped it. If I put the old ram back it is still a bit stiff, but it works - turn calls are acted on and it stays in "AUTO".


Baffled!
 
Is the new drive trying to drive the rudder the "wrong" way. Try reversing the power leads to the drive.
 
What happens if you disconnect the ram arm from the rudder/quadrangle, or whatever?

If you ask for +10 and the ram moves its full length, (or more than twitches), it's something to do with the pressures that arise with the ram connected to the rudder.

If you ask for +10 and the ram twitches then Standby, it isolates the problem a little.

If the latter, do you know how to power the ram with a power supply independent of the computer..... If so, you can power the clutch and ram, fairly momentarily, and see if the ram moves freely.... I think this would then isolate the problem to the computer.

I had similar problems in 2006/7 and it turned out I had fitted the 4 small gears upside down... They have a ridge on one side, but not the other - the wrong way up and the ram jams when under pressure from the rudder and steering cables, and gave the same symptoms as yours. i.e. the ram moved freely when not connected to the rudder, as in my first step above.

Just remembered you've tried a different linear drive so, unless they both have the same problem, (which they might), it's probably not the drive. Still worth checking if it moves OK when not attached to rudder.
 
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It doesn't make sense to me. All the computer does is supply 12v. So if the drive works with 12v it should work if the computer works, which it does because the old drive works.

The only things I can think of are that the new drive is defective and drawing excessive current which the 12v supply provides, but the computer cannot. Try measuring the current.
Any chance the new drive is 24 v ?. The old 300 had limited error messages and may recognise its not 12v and shut down without telling you why. A 24v motor will still usually work from a direct 12v feed.
 
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It does the same thing when disconnected from the quadrant. For what it's worth I have had both motors out of the rams and connected to the drive output of the controller. They behave exactly the same. Twitch, then flash "ST7000" then back to standby.

Each of these motors, when fitted in the old ram, work ok (but the old ram sticks, remember so cannot be used)

I beleive this is a closed-loop system - the rudder angle sensor provides feedback to the controller about rudder position. Could it also be informing the computer about whether the rudder is moving after a turn call has been made? In which case could it be that the twitch is meant to move the rudder but because it is not moving it enough according to the rudder anglesensor, the controller thinks there's a fault?
 
noelex - thankyou, I'm pretty sure the motor is 12v, the ram rating plate says 12v. In any case I put the motor from the old ram in the new one and it behaves the same.
 
concentrik said:
Each of these motors, when fitted in the old ram, work ok (but the old ram sticks, remember so cannot be used)
Click to expand...

That rules out the motor. My suspicion would therefore switch to the clutch. The clutch operates backwards to the way you might initially expect. 12v power locks the clutch allowing the drive to work. No 12v frees the clutch.
The clutch is a simple electromagnet. Can you compare the resistance of the coils on the 2 different drives. They should be the same obviously.
The computer provides power to the clutch. If its defective and the clutch is drawing too much power the computer will shut down.
 
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