Alarm: Bypass/ clutch overloaded

G

Gyda

Guest
I have just mounted a 711-C autopilot connected to a Simrad HLD-2000 linear drive unit on a 47ft sailboat, and have only been using it a couple times (after successfully done the initial setup and sea trail). Today, the pilot came up with an alarm: “Bypass/ clutch is overloaded. Please turn OFF and check drive circuit”.

I´m not able to find anything wrong with the steering mechanism what so ever. I´ve tried to shut the autopilot down completely, but the same alarm occurs when I turn it on again. I´ve tried to do the dockside setup but are not able to go through with the rudder test because the alarms comes up immediately when the test is initiated.
The rudder limit is 30 degrees when turned hard-over on both sides, which also is the value put in the Rudder limit setup menu.

The linear drive unit has been in the boat for years working flawlessly with the old Simrad autopilot, and has not been touched in any way, so there should not be an air bubble issue, I think.
I run a diagnose on the processor unit and it showed: Bypass/Clutch: Present
What should I do..?
 
If you with the dodge buttons mean the port and stb key, nothing happens with the rudder when they (one at the time) are operated.
When the pilot is turned on it goes straight to installation mode. (May be because the rudder test not has been successfully completed). I have to acknowledge to get into the installation menu, and then go out of it and into stand by mode.
When the port or stb key is operated, the control unit beeps and show "Fail" in the display.
Then the message regarding the bypass/ clutch showes up.
 
It sounds like the linear drive unit has developed a problem. Just to make sure it isn't the pilot, I would recommend you remove the wires (including the clutch output) going from the pilot to the drive unit. Then put a meter on the pump output of the pilot and run the dodge back and forth an see if the pilot will try to work. You should get voltage on the pilot output. Because the pilot wont see the rudder feedback move, it will most likely will get a rudder drive error, but should allow you to test the power. You might need to get a dealer on the boat.
 
The voltage from the boat to the pilot is 24V.
When I do the Rudder setup and Auto test, the control display shows: Drive Unit - reversible 12V (it is a Hydraulic linear drive, Simrad HLD-2000).

When I measure the output voltage to the drive unit during the rudder test, it shows 17,3V, but during the same test it shows an output voltage to the bypass clutch between 24,3 – 25,2V…?

It is stated by Furuno that the 711C is compatible with the Simrad HLD-2000 drive unit, but to me it looks like the 711C don’t adjust its output voltage to fit the existing drive unit...?
 
This seams to be an issue regarding the voltage output from the pilot to the drive unit and bypass valve since it show different Voltage output between the drive pump and the valve.

I`m really looking forward getting this cleared up, since I don´t have a functional autopilot at the moment, and no dealers whitin reach.
 
Gyda,

The Furuno pilot can operate as a 12vdc system OR a 24vdc system.
What you feed it, is what it gives out. If you have a 12 volt drive unit, you must feed the pilot 12v etc. So you are feeding it 24vdc. That means the readings you took are exactly as expected. Based on your reading, you are getting 24v to your clutch and 24 volts to your drive system. (When doing setup you can turn the knob and select 24v from the selection..12v is the first item in the list but the installer needs to pick the proper selection. Improperly picking 12v will not change your output; it will still be the 24v you are feeding into the pilot) Keep in mind that the drive system voltage is pulse modulated so your meter will show it as a lower voltage because of the freq pulses. So at this point your pilot is acting as expected. You should verify your drive requirements and ensure it is a 24v drive system with a 24v clutch input. I suspect you have a 12v clutch and the system worked okay for awhile until the clutch coil was damaged. I suspect the damage is now causing too much current to be pulled on the clutch circuit of the pilot resulting in your error. If you find it was correct and you do have a 24v clutch and 24v drive system, then you should do more testing. I would connect the drive system clutch input (via a 3 amp fuse) direct to your 24v power system. Then connect the normal drive wires to the pilot and setup the pilot as a 24v reversible system, then test to see if it works. If it works fine then something has happened to the pilot clutch output and the unit would need to be checked out. If the fuse blows on the clutch feed you tied direct, then you have an issue with the clutch on the drive unit you must repair/address. If you do have a 12v clutch input then you know how it went bad. You could always repair it and then use a large knock down resistor to knock down the 24v clutch signal so you can use it with your 12v clutch. If the entire drive system is 12v; then you should be feeding the pilot 12v so you get both a 12v drive and 12v clutch. I hope that makes sense.

Another thing to consider while you have the clutch directly powered; can you steer the helm? If you can, it doesn't sound like your clutch is working.
 
Problem solved after rebuilding drive unit with 24V clutch and pump.
 
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