[TG] [TG11] Fluxgate compass / course computer troubleshooting

[tmass60]

My system includes an E12091 S2G AST course computer with a connected M81190 fluxgate compass. During last season from time to time the heading information would be shown incorrectly. I would reset this via the sea trial wizard either manually or via COG which would resolve it temporarily.

When relaunching this season the same issue appeared but on a much more regular basis and the "reset" would only resolve the problem for a very short time, in some cases as soon as the boat changed heading. I replaced the fluxgate compass with one that tested OK per the following procedure https://forum.raymarine.com/showthread.php?tid=96. (The old one I removed tested on the lower size of all the resistance targets but still within tolerance.) Location is the same as the old one (where installed by the OEM) and the new compass swing test netted just 2 deg variation.

With the new fluxgate compass installed I again manually had to reset to the proper heading. The proper heading held and reflected the correct boat heading throughout about a 6 hr sail. However, every time the power is cycled the heading has to be reset manually again to the correct heading.

Nothing has been changed in the wiring between the compass and the course computer. All other autopilot functions seem to work perfectly. Does that leave the course computer as the only likely problem? Any other troubleshooting steps I need can try before I either replace the E12091 with a used one from ebay or change the whole system out to the newer EV1/ACU200?

Trying to avoid just replacing things if there is some setting or other solution I should be checking first.

Thanks,

Tony