E125 heading display stability

[jgonnerman]

I have an e125mfd with an st 8002 control head and a smartpilot.
The smartpilot communicates with the MFD via an NG converter.
When at crusing speed 8-10 knots and lower the heading readout on the MFD is highly erratic varying both left and right 60-90 degrees. This occurs in all steering modes. Standby,auto and tracking. The heading reading does not vary on the control head and the auto pilot does not seem to respond to the mfd heading change.
The NG converter also is fed by the Raymarine GPS and st60 depth sounder and these read outs remain stable which would likely indicate the converter is working.
The heading deviation will last 0 to 3 seconds and then return to the correct reading.
The flux gate has been swung and COG and heading aligned.
The only reading the erratic heading shows on is the MFD.
When the heading jumps the radar set on heads up shows bad info momentarily until it restores to the correct heading value.
If the chart and radar pages are set to course up only the digital heading value and vector jump but I don't always want to enter a waypoint close to my desired direction as a workaround.
Is this possibly a cabling/connection issue or a MFD software problem?

[Chuck - Raymarine - Moderator]

Welcome to the Raymarine Forum jgonnerman,

We haven't had any similar reports except from systems which may have had a second source of heading data or possibly been interfaced in a manner which had created a data loop. In order to support further investigation of this issue, please
- ensure that the MFD's Bridge NMEA Heading configuration item (HOME->SET-UP->EXTERNAL DEVICES->NMEA SET-UP->BRIDGE NMEA HEADING) has been set to OFF. Should it have been previously configured to ON, then re-test after having configured this setting to OFF
- re-test the system after having blocked reception from its NMEA 0183 communications interfaces. This may easily be accomplished by configuring each of the MFD's NMEA 0183 ports. Should the problem persist afterwards, then back up your waypoint, route, and track data to a microSD memory card, perform a System Settings & Data Reset, manually reconfigure the MFD's settings, and then re-test
- should the problem persist, then
----- create and attach a system diagram to a response to this thread. The diagram should identify the make/model of each marine electronics item and any computers which have been interfaced to the system.
------ create and then attach the Diagnostics...html file from your system.