Auto helm won't start - Windlass won't stop !

[superheat6k]

Had a lovely trip out on Sunday across from the Hamble to Osborne Bay for a picnic lunch.

But the Autohelm wouldn't work - power on the control heads at both helms, but every time I selected 'Auto' I got a Low Voltage beeping alarm message, which I assume means the high amp supply has failed. Subsequent checks back at the berth showed no reaction from the helm pump.

Then when I pulled the anchor up the Windlass wouldn't stop.

I hope these are isolated faults that simply coincided. Looks like I know what I will be trying to sort out this weekend !

Anyone had the auto helm Low Voltage alarm ? - Control heads are Raymarine ST7000, but the course computer looks like the older 100 / 300 style - 1991 boat.

 

[Montemar]

It could be corroded connections and switch mechanisms.
Switch mechanisms sticking due to lack of lubrication.
Dirty contacts having a high resistance that lets voltage appear but as soon as current is requested but can't flow which then manifests itself as low or zero volts. I had this problem on a wiper where I had volts across the wiper supply plug when switched on but then disappeared when plug connected to the wiper. The problem was in a plug and socket between helm switch and wiper and caused by corrosion. It was an easy fix that initially looked like a short circuit in the wiper but lack of fuse or circuit breakers blowing indicated there was no current involved.

 

[superheat6k]

Having spent an entire morning cleaning and remaking every connection to my course computer, including re-positioning it to somewhere serviceable other than by Houdini, and to no avail, I decided to give up and take a walk around the boats I can't afford at the British Motor Yacht Show.

Then I googled the problem to find a very specific answer for the Autohelm Type 100 Course Computer displaying 'Low Battery' alarm when selecting Auto. A specific diode was found to be weak and would blow. The resolve was to solder another diode across two pads on the back of the computer PCB, and (hopefully !) problem solved.

If anyone else suffers this issue with a pre 1997 type 100 computer the PM me for the PDF technical bulletin from Raymarine.

The windlass not stopping was a duff, and recently replaced, deck switch.