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Fenix 7X Pro - possible defect with compass and altimeter?

MEGATREON

Hi forum, since a few weeks ago, possibly with a beta update, my watch started acting up.

  • First symptom was a compass not settling in the widget and the mini version of it, it keeps spinning and is way off the "true" north from the map at my home.
  • I distinctly remember it to be spot on and settling immediately when the unit was new, and it could catch a slight z-axis-rotation with tremendous accuracy. Well, not anymore.

Then, during mountaineering and hiking, I notice the altimeter to count too much elevation gain, both up-hill and down-hill. During an activity:

  • On the map, I will see very short lateral "jumps", consistently, but seemingly in a random direction. The location indicator almost immediately returns to the "correct" position.
  • The altimeter seems to act up, see attached picture. The altitude will jump exactly by the same amount, but at random intervals.

Has anybody experienced something like this?

I am aware that these may be two different issues.

For the record:

  • Yes, I recalibrated the compass numerous times.
  • Yes, I restarted the watch.
  • Yes, across the recent beta updates the error is consistent and present.
  • The altimeter port seems clean, and this shouldn't affect the compass at all.
  • The only IQ field I have installed (and enabled in the hiking activity) is the one that records tempe values into a FIT file field, since I want skin temperature and env temperature separately recorded.

Top Replies

  • in reply to trux +1 suggested
    trux said:
    So for example at the end the rose points to some 218°, while the display shows the value 155 (and without the ° sign). Which units do you use? Did you try using the magnetic north instead of…

All Replies

  • 0
    MEGATREON said:
    On the map, I will see very short lateral "jumps", consistently, but seemingly in a random direction. The location indicator almost immediately returns to the "correct" position.

    Do you mean "lateral jumps" of the track recorded on the map of the activity, or something else? If so, then it rather looks like a GPS problem. Possibly due to a bad signal. Verify whether you use the best possible GPS option in the concerned activity profile.

    MEGATREON said:
    The altimeter seems to act up, see attached picture. The altitude will jump exactly by the same amount, but at random intervals.

    It could be indeed a problem with the altimeter. Or it could be also water or sweat in the pressure sensor port. Do you see similar irregularities of the elevation, when you open the altimeter widget? Could you post a link to the activity - perhaps we could see some clues there.

    MEGATREON said:
    Yes, I recalibrated the compass numerous times.

    Why? Do you have problems with the compass too? You did not mention any. Rather try calibrating the altimeter, though it is unlikely to help with the symptoms you described.

  • 0 in reply to trux
    MEGATREON said:
    • First symptom was a compass not settling in the widget and the mini version of it, it keeps spinning and is way off the "true" north from the map at my home.
    • I distinctly remember it to be spot on and settling immediately when the unit was new, and it could catch a slight z-axis-rotation with tremendous accuracy. Well, not anymore.
    trux said:
    Why? Do you have problems with the compass too? You did not mention any. Rather try calibrating the altimeter, though it is unlikely to help with the symptoms you described.

    Maybe reading the entire post first would help....just saying......

  • 0 in reply to clonetrooper
    clonetrooper said:
    Maybe reading the entire post first would help....just saying......

    OK, I apologize, I see it now, but have the feeling the first paragraph was not there when I replied (or my browser did not load it).

    I'd check whether the compass is in the Magnetometric or GPS mode. If it is in the Auto mode, I'd force it into the magnetometric mode and test whether it makes any difference. If it helps, then the problem is indeed with GPS. If it does not, then one of possible and quite frequent reasons for misbehaving compass are magnetized springbars. I would test the compass with the springbars removed.

  • 0 in reply to trux

    Hi  and  , thank you both.

    > I'd check whether the compass is in the Magnetometric or GPS mode.

    I have recorded a video of it:

    For comparison, a 6S pro compass right next to it, to demonstrate and verify that the location does not have any particularities.

    • My 7X behaved like the in right view in the beginning, but some time ago it started to show the symptoms (see the watch on the left).
    • And yes, magnetometer mode is selected.
    • Also, I removed the replacement wristbrands just to check whether they are magnetic. Nope, that was not it, also.
    • The 7X is 2 years old, the 6S Pro is 4 years old.

    Regarding the GPS lateral jumps and altitude inconsistency:

    • I've checked the FIT file with https://www.fitfileviewer.com/
    • In the column "enhanced altitude" in the section "Record" I see only ever steadily decreasing values, consistent with the terrain.
    • Same for the "GPS meta" section.
    • Recording interval 1s (consistent in both sections)

    I can only conclude that these jumps and what you see in the screenshot from the initial post is so short that is is never recorded, but only used for calculation.

    However, the recorded data also suggests that there is no error in the altimeter, because the recorded data seems consistent. I did not check the whole file though.

  • 0 in reply to MEGATREON

    Hang on, I may have found something: There is a column `cycle length16` which shows strange and inconsistent data:

    The value makes no sense, but the timing (a few seconds apart) seems consistent with the unit's "lateral jumps" and altitude glitches.

  • 0 in reply to MEGATREON

    length16 is the circumference of the cycle wheel. Try disabling the auto-calibration, and set it fix. Possibly your speed sensor needs a new battery.

  • 0 in reply to trux

    That possibly does not make sense. It was a hiking activity (see initial post), and ~400m circumference seems way off Sweat smile also, on this page they say it's "distance per stroke"? And it is not recorded consistently, and it seems to have strange values?

  • 0 in reply to MEGATREON

    ... however, the length16 anomaly is unlikely related to the compass issue.

    Seeing that the bezel scale is correctly oriented and showing the same orientation as the other watch, and only the numeric value is wrong, I'd tell either the units are wrong, or the True North value on your watch might have been incorrectly updated. Try setting the Magnetic North Reference, and check the units.

  • 0 in reply to MEGATREON
    MEGATREON said:
    also, on this page they say it's "distance per stroke"?

    Well, more specifically it is the distance per cycle, which can be indeed a stroke in rowing or water sports. I thought your activity was cycling, not sure what it is doing in your hiking activity.

  • 0 in reply to MEGATREON

    Do you have some data in the Cycle Length16 field in older hiking activities (or in activities from the other watch) too?