B&G Network Pilot repair

[Glen Roger]

I've just won a nasty fight with a B&G Network Pilot. It could have gone either way. But in the end, Good (me) triumphed over evil, although I didn't make it easy on myself. I made lots of mistakes which I've not elaborated on here.
*
I've decided to post this, 'cause I could find precious little in the vast resources of the internet on how these damn things work. So maybe this will help someone else.

There is a large allen head screw that holds the ram to a base and allows some xyz degrees of freedom so the unit can follow the piston connection to the rudder. Three times in the last 10 years, that allen head screw has come loose. When that happens the ram is no longer connected to the boat and the network computer goes nuts. The first two times, all that was involved was disconnecting the base from its mounting, pulling out the pin that secures the ram to the swivel point, screwing back in the allen-head mounting screw and putting the whole thing back together. And the first two times it happened, several years apart, I did not have any loctite to better hold the screw in place.
It happened again just recently and this time it was a real mess. it actually tore the linear rudder reference unit (rru) apart and moved it significantly from its appropriate position.

It has taken me a couple of weeks to figure it all out. But here's what I learned.*

The linear rru has a little potentiometer at one end. There is a swivel "screw" that runs down the barrel. As the piston moves in and out, a guide runs along the swivel, causing it to turn, which causes the potentiometer to turn.*
So that's how that works.

The ram is a hydraulic ram. Nothing more. I wasn't sure if there was damage to that so I took it into a shop and had them check it out and put in new seals. Should have been easy but they put the piston back in backwards so that took a bit of time to figure out and get fixed.

When I put it all back together it didn't work. I could not successfully "commission" the unit. Turned out, the problem was the starting and ending position of the potentiometer in the rru.

When you align the linear rru to the ram you need to check the voltages as you rotate the wheel from starboard to port. You need a low voltage at port and a high voltage at starboard... somewhere between 2 and 5 volts. To adjust you simple rotate the piston in the rru until it is low at one end and check that it is high at the other end.

As I tried to get the ACP Network computer to accept the voltage values for extreme port and extreme starboard I struggled to get the system to even recognize that the rru was present. I tried a system reset, I went through the built-in diagnostics and I tried over and over to go through the first 5 commissioning steps 1) Set installation to Sail, 2)Set Port Extreme, 3)Set Starboard Extreme, 4)Set Midship and 5)Set Port to Starboard timing.
I can't tell you why it finally worked, but just going through the system diagnostics and trying the 5 Commissioning steps over and over finally paid off.

I hope other people will comment to develop a better understanding for how these things work and form a resource that will help others.

All this said, I'm pleased with the quality of this vintage B&G equipment and I intend on keeping it working.