Re: [Amel Yacht Owners] Re: Bow Thruster won't come up

Bob Grey
 

Duane, I have an Amel 55 and had to replace a magnetic limit switch on my  dingy Davits due to workers at a yard respooling my winch in reverse. It didn’t stop before crushing the switch.

The switch was an RS electronics model but no longer available, so I spent some research time evaluating options, Amel in the end found an old one in stock. I originally thought it was a Hall effect sensor but found out it was a glass red switch with changeover contacts, with only the normally closed contacts wired in.

Thus my confidence in making the statement that magnetic based glass reed switches come in 3 versions, normally open closing when a magnet field is applied, change over (NO/COM//NC) and NC opening when a magnetic field is applied as it only wires in the NC/COM contacts of a changeover switch.

Bob Grey 

On Tuesday, February 6, 2018, 03:01, sailor63109@... [amelyachtowners] wrote:

 

Bob,


I posted in https://groups.yahoo.com/neo/groups/amelyachtowners/files/Bow%20Thruster%20Maintenance/ in the FFV.pdf file the manufacturers sheet for the linear actuator switch.  I believe ours is the 4th switch from the right.  I also posted photos of the linear actuator switch and the control board (front and back) in https://groups.yahoo.com/neo/groups/amelyachtowners/photos/albums/161606487

I don't see that this is a 3 contact switch, it only has two wires coming from it.  Do you have something other than the Super Maramu?  Maybe your setup is different.  You will note on the photo of the switch the little switch symbol shows it as a normally closed switch, and you will see the same icon in the FFV.pdf file from the manufacturers literature, and listed as a normally closed switch.

I opened up the black plastic casing and there is a circuit board inside.  I'm not an electronics guy but there are gizmos on the board that are likely transisitors, resistors, and the reed switch.  I could post photos of that if there is any interest.

The disconcerting thing about this is that a simple reed switch should show continuity either with a magnet (normally open), or without a magnet (normally closed).  This switch does not show continuity with or without a magnet, leading me to believe there must be power present for the switch to operate.  I had an electronics tech in the marina verify my tests and he agreed.  We oriented the magnet in all directions and reversed the leads fo the multimeter to possibly account for polarity.  Taking into account the fact that the symbology on the switch identifies it as a normally closed switch, and it does not show continuity, there must be an electromagnet or some other means to close the switch for the "normal" position so that the magnet on the actuator can open the circuit.

Takeaway:  order it from Maude or the factory.

Duane
Wanderer, SM#477

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