Type 1 Linear Drive Resistance Readings

[lpdsn]

Is there anyone with a Type 1 (autohelm or Raymarine) linear drive and a multi-meter that could check the resistance readings across the nmotor and clutch for me? Obviously powered off.

I'm beginning to suspect my motor but I'd like to compare notes before I disassemble everything and take it away for refurb.

 

[miyagimoon]

Is there anyone with a Type 1 (autohelm or Raymarine) linear drive and a multi-meter that could check the resistance readings across the nmotor and clutch for me? Obviously powered off.

I'm beginning to suspect my motor but I'd like to compare notes before I disassemble everything and take it away for refurb.

I don't know the resistance values but if you apply 12v to the clutch leads you should hear it click in removing the 12v it should click out. Same with the motor 12v it will move the ram one way reverse the voltage and it will move the other way.

 

[LadyInBed]

Don't be shy to take it apart and clean the carbon dust out of the motor and check the brush length.
It's not a difficult job.

 

[lpdsn]

Thanks both. I'm after the resistance measurements if you're able to help there.

I have taken it apart a couple of times. I even cleaned the bushes the Christmas before last (and it did make a short-term difference). I won't be doing that again. It's an extremely difficult job getting the 10V motor back together ( I can only presume Autohelm changed the motor at some stage as it is nothing like the YouTube video or I presume those of the posters that found it easy) so if I have to get the motor refurbished I'll get it done professionally. Fair few workshops round Belfast where I could take it, so I have no difficulty with that.

What I'm trying to avoid though is just blindly replacing or refurbishing parts of the drive. I've already replaced the gears when it turned out the old gears were fine. I measured the resistance and suspect the motor. I just need measurements from a 'good' drive for comparison.

 

[DJE]

I'm in the process of installing a brand new one and it's not yet wired up. I'll try and get down to the boat in the next day or so and take some readings for you.

 

[Richard10002]

Is there anyone with a Type 1 (autohelm or Raymarine) linear drive and a multi-meter that could check the resistance readings across the nmotor and clutch for me? Obviously powered off.

I'm beginning to suspect my motor but I'd like to compare notes before I disassemble everything and take it away for refurb.

You’ve probably told us in your other post, but what are the symptoms?

 

[lpdsn]

I'm in the process of installing a brand new one and it's not yet wired up. I'll try and get down to the boat in the next day or so and take some readings for you.

Thank you. Appreciate that.

 

[lpdsn]

You’ve probably told us in your other post, but what are the symptoms?

I'd assumed I'd bored everyone in that other thread over the last 15 months.

The AP bails out with a "Drive Stopped" message. New(ish) 2014 Raymarine electronics but original autohelm drive.

It stopped working when the steering was temporarily stiff (hadn't realised when I first turned AP on so I could take in the fenders just after casting off - the boat had been moored in a river so I suspect some debris had got caught on top of the rudder - steering cleared up in a nice F7 beat a week or so later and has been fine since). In hindsight, I'm not sure whether or not that was a co-incidence.

I took the drive apart, cleaned the bushes (it was a triumph of ingenuity and anger management getting the motor re-assembled), roughened the surfaces of the clutch, soldered replacement wires on the clutch, checked gears and re-assembled it. Initially that did the trick, but after a couple of hours it went back to the way it was (not sure whether it was significant that the first failure afterwards was when crew grabbed the wheel whilst it was operating - probably not).

Anyway, there was lots of advice re gears and I couldn't be sure there wasn't hidden wear and tear on the plastic gears, so I thought I'd buy it new gears for Christmas. The old gears were fine, so that wasn't the problem and "drive stopped" messages still appear.

Sat in the steering compartment with a multi-meter whilst it was operating. Nothing seems wrong with the power supply. It works normally with regular short bursts on the motor making minor adjustments and then it just seems not to try and the control head beeps.

Had the idea of measuring resistance. I initially was thinking in terms of a poor connection between ACU and drive, but no issue found. However the resistance across the motor was quite a bit higher than I'd assumed it would be. 2.6 Ohms, IIRC - it's noted in the other thread and my diary. Hence wanting to compare notes.

 

[LadyInBed]

Is the Rudder Reference Transducer working OK?
I'm not sure how to test it, maybe disconnect the rod, put AH to Auto then gently change the angle on the RRT and see if the Linear Drive moves?

 

[DJE]

Thank you. Appreciate that.

Tested my new unit this morning and got 11 ohms across the motor and 25 ohms across the clutch. Open circuit between the clutch and the motor. Surprisingly high motor resistance for a 12V unit but I repeated the reading several times after moving the pushrod and always got the same reading within 0.1 ohms. But presumably the clutch is disengaged so the motor doesn't move.

In service the motor resistance must be less than this or it wouldn't develop very much power. Perhaps having never been run the brushes need to bed in? The drive unit has yet to be connected to the controller.

Hope this helps but I'm a bit baffled myself.

 

[lpdsn]

Tested my new unit this morning and got 11 ohms across the motor and 25 ohms across the clutch. Open circuit between the clutch and the motor. Surprisingly high motor resistance for a 12V unit but I repeated the reading several times after moving the pushrod and always got the same reading within 0.1 ohms. But presumably the clutch is disengaged so the motor doesn't move.

In service the motor resistance must be less than this or it wouldn't develop very much power. Perhaps having never been run the brushes need to bed in? The drive unit has yet to be connected to the controller.

Hope this helps but I'm a bit baffled myself.

Thanks. I really appreciate that. I got a very similar reading from the clutch but a lower resistence from the motor (2.5 Ohms) which I thought was high. So I'm still baffled.

By the way, the way the clutch works is that it clamps onto a plate which stops the planet gears rotating freely, which then means the motor is connected to the arm. Without that the motor is disengaged so even if it ran the gears would just spin. That's how the arm can move when the AP is off. So when testing you can power up the motor independently.