My build is as follows:
- S900
- A2
- Zenmuse Z15-GH4 gimbal
- iOSD Mark II

This is a two person setup:
- The pilot's radio communicates with the A2 controller through an external Futaba receiver.
- The second radio communicates with the Z15-GH4 gimbal via a Futaba receiver as well.  The video from the gimbal is sent to a Wireless VTX, then sent to a Black Pearl monitor on the ground.
- The pilot's FPV camera's video, along with the A2's telemetry, is sent to the iOSD Mark II.  The Mark II then outputs its video to a second Wireless VTX which is then sent to a second Black Pearl monitor.
All firmware has been updated to the latest version - as of April 11, 2016:
- A2: v2.7
- Zenmuse Z15-GH4 gimbal: v3.0
- iOSD Mark II: v3.02

Steps to demonstrate the problem:

1. I made sure the S900 is level.

2. Next I calibrated the A2's IMU.

3. Balance the gimbal.  Here's a video that shows the gimbal balanced:



4. Calibrate the gimbal.  This video shows the gimbal going through its calibration process:



Notice the gimbal is not horizontal and the camera points down a little.
Note: I've gone through the calibration process at least 20 times.

5. Power down, then power up the S900.  This video shows the gimbal initializing itself:



Notice the gimbal is still not horizontal and the camera continues to point down.

6. Test the gimbal for horizontal drift.  This video demonstates the problem:




More Background:
I believe this problem started when I was running v3.0 on the gimbal, v2.6 on the A2, then calibrated the A2's IMU.  Before that I don't think drift problem existed, and, my gimbal was way out of balance too.

Questions:
- Is the configuration I'm using, hardware and firmware versions, supported?  By supported I mean has QA tested all of these components to make sure they work together?
- Can the IMU be indirectly causing this problem with the gimbal.  I'm assuming the gimbal communicates with the IMU to determine what's horizontal, etc.

DJI -  could you please respond to this post with your thoughts on what is causing this.  There's so much drift with the gimbal that it's unusable.  I've got over $10k into this build and unable to use it.

Hey Timon I have the same exact setup you have.  I will check my gimbal firmware and settings.   Everything on all my crafts are working with out any problems.   I will let you know which firmware I am on in about 2 hrs

timonroecg@gmai Posted at 2016-4-12 20:55
DJI -  could you please respond to this post with your thoughts on what is causing this.  There's so ...

They will tell you to contact support and send it back...while you're waiting for DJI here you might just as well contact support...email or call...if you call they will email you with some information to send so I dont even call anymore...I'd email support with the videos and wait for a response...more than likely it will be a questionnaire...fill that out, again with links to the videos. Then they should send an RMA and a second email with shipping labels. Plan on 3-4 weeks to get it back...if you get it back sooner book a flight to Vegas because you are on a lucky streak.

Problem has just gotten worse.  Gimbal is making grinding noises and is completely freaking out now...

you need to contact DJI support so they will issue you an RMA

Just found something really interesting...

I removed this gimbal and reinstalled my old Z15-GH4 gimbal, from this thread old Z15-GH4 gimbal thread, and it does not have the horizon drift problem.



Here's the firmware I'm running on the old gimbal:


Notice I'm using v3.0 but the CMU is v1.0, latest is v1.2, and the HD-AV is v1.18, latest is v1.20.

Also, the old gimbal is not even close to being balanced.

On the gimbal that has the drift problem I'm also using v3.0 but the CMU is v1.2 and the HD-AV is 1.20, all the latest.

Wondering if v3.0 of the firmware, with the latest CMU and HD-AV, is causing this problem.  Anyone else out there running all of the latest component versions in the v3.0 firmware and not having this problem?

And...  is there a way to rollback to the older component versions in v3.0 of the firmware?

Just noticed another odd thing with the old gimbal's firmware.  If you look at this thread, old Z15-GH4 gimbal thread, here's the version information reported from the Assistant:



This is when I had the bad HDMI board in it, the firmware version information reported all the latest component versions in the v3.0 firmware.

After replacing the board I somehow got older versions of the CMU and HD-AV:

Please note that the update in GCU  v3.0 only applies to A2 plus Lightbridge 2 systems and only supports DJI GO v2.5.0 or above.

DJI-Adela Posted at 2016-4-13 04:05
Please note that the update in GCU  v3.0 only applies to A2 plus Lightbridge 2 systems and only supp ...

This is what i told him about.  Adela how does someone like timon downgrade the firmware?  I know there is a way and why are there no instructions on how to do it?  We should not have to send out our gimbals to dji repair just
to downgrade a firmware.  Any way you can provide us we the instructions it would be great.

From the DJI Z15-GH4 release notes:

Major Update
GCU firmware v3.0 supports gimbal auto calibration through the DJI GO app.

Note:
This firmware only supports DJI GO v2.5.0 or above.
This update only applies to A2 plus Lightbridge 2 systems.

DJI-Adela - are you saying that v3.0 of the firmware will prevent the gimbal from working correctly, as I've described above, if my build does not include 'DJI GO v2.5.0 or above' and 'A2 plus Lightbridge 2'?

If that's the case:
1. The release notes did not make that clear.  The phrases 'only supports' and 'only applies to' does not translate to 'will prevent your system from working correctly'.
2. If this is the case it's totally unacceptable from a software quality standpoint.  A new version of software, in any environment, should not prevent the user's system from working.  The only exception that I can think of is if the hardware it's running on is no longer supported, which isn't the case here.  If a user installs a new version of the firmware at worst it should have no effect on their system.

Can you please clarify what you're saying about v3.0 of the firmware and the impact it will have on a build that does not include 'DJI GO v2.5.0 or above' and 'A2 plus Lightbridge 2'.

Also, to repeat flaviomj, how can I downgrade the firmware??

And, I created a problem report two days ago, #281210.  Can you please get someone to look into this asap.  I've heard nothing back from DJI and my system is now unusable.

Timon there is a note about the firmware being for dji go and lb2 users. It will show up after you click download and the upgrade window comes up.  Before you press upgrade button it will tell you the notes.  You have to be very careful because most people will press the upgrade button without reading the notes.  

I did see that and assumed it was the same information that appears in the release notes...  maybe not though.

2.5 days later and nobody has responded to my Problem Report that I sent via email.  So I called DJI Support in the US again and was able to get through to the Spreading Wings group.  They looked at this thread in the forum and didn't have anything else for me to try so want me to send it in so they can investigate.

The Tech Rep did say two things though:
* Installing the latest firmware should not negatively impact your system.  It does not matter that I don't use Lightbridge or the DJI Go App.
* There's no way for us to rollback the gimbal firmware.  He did think DJI techs do have this ability but nothing is available to customers.

I'll report back what DJI finds out...

I find it very strange that there is no way to do roll back of firmware.  The phantom series has a way if I am not mistaken.  Why would they add that to the phantom and not to the S wings?    Also, tech support telling you that the latest firmware SHOULD not negatively impact your system is not very reassuring answer.   The reason why they don't ever say that it doesn't or will not impact is because if they tell you that it does not impact and you can prove that it did cause problems well...  They are in shit.   What it all comes down to is that no one should update their system unless it is really worth doing it or they have done extensive research on forums to see if that update caused issues.   Don't ever rely on just what DJI says because I am sure from what you have seen on here that their testing is very limited because they want to push out and start making money.   

What I do find it ridiculous is the fact that they do not want to share how to downgrade or allow people to do it because it must be a huge source of income as well, because every time something like that happens you have to ship the item to them and they could possibly charge you for it.

Let me know what they find out.  I am wondering if it is the update that caused the problem, if they will actually admit it.   Specially since they just told you it should not cause problems.   

timonroecg@gmai Posted at 2016-4-14 20:40
I did see that and assumed it was the same information that appears in the release notes...  maybe n ...

PM me or email me at dennismurry08@comcast.net   I can help with instructions to roll back

dennismurry08@c Posted at 2016-4-15 17:34
PM me or email me at    I can help with instructions to roll back

Hello! Can you help with the way how to downgrade ztnmuse GH4? Is it possible to downgrade CMU firmware? Thank you in advance, I'm just stuck with the latest 3.0 firware...

Igoris - email dennismurry08 for instructions as per his post above.

Already done - mail sent. Still no reply.I can't PM - where is the button? Or my state on this forum is too low?

COBRA [project] Posted at 2016-4-27 01:39
Already done - mail sent. Still no reply.I can't PM - where is the button? Or my state on this forum ...

If you're Igor...I sent

dennismurry08@c Posted at 2016-4-27 17:45
If you're Igor...I sent

Yes, I am))) thank you!

Update...   just heard back from the DJI North American Support group.  Here's the content of the email they sent me on what they did to my gimbal with the drifting issues described above...

"Your unit has been evaluated and repaired according to the repair center's assessment.  There were no critical issues found, the unit was calibrated to factory specifications and has passed several inspections before being prepared for shipment."

Curious to see if they did anything with the firmware.  I should be getting it back this week and will update this thread.  

Update...  got the gimbal back from DJI and the horizon drift problem is fixed...



The firmware is the latest version (v3) as of today - May 11, 2016.  Also has the latest version of the HD-AV.



Notice the gimbal has been adjusted but is not balanced.  It also doesn't have complete movement in all directions but did when I sent it in.



So whatever adjustments they made fixed the drift problem but obviously doesn't matter whether or not the gimbal is balanced.

timonroecg@gmai Posted at 2016-5-12 06:28
Update...  got the gimbal back from DJI and the horizon drift problem is fixed...

Horizon Drift Fix ...

Have you tried balancing it without the lens cap on? More times than not adding even a little more weight, like the cap, can throw off the gimbal since it's not expected to be there during normal use. Also, could you happen to provide a picture of how the camera is seated from a side angle to better address the movement issue?

The gimbal is unbalanced without the lens cap as well...



Here's a view from the side:



You can see it sits pretty far back, the slot on the bottom of the camera won't allow it to go any farther back on the gimbal, but the gimbal is still front heavy (falls to the front).

I'm not concerned about the gimbal being unbalanced as it appears to not matter.  The DJI Techs did make adjustments though which fixed the drift problem.  I just can't tell how they know which adjustments to make as the gimbal works but isn't balanced, an also wonder if these adjustments change from version to version of the firmware as I believe this drifting problem started happening when I upgraded to the latest version of the firmware.

timonroecg@gmai Posted at 2016-5-13 20:22
The gimbal is unbalanced without the lens cap as well...

Zenmuse Z15-GH4 - Unbalanced, Without Lens ...

The repair technicians do use additional equipment to further calibrate the servos when the standard Gimbal Auto Calibration does not suffice. This additional calibration may not be needed for every firmware update, as the overall wear of the gimbal would also need to be put into consideration. The gimbal should have been balanced prior to shipping back to you, as imbalance can wear out the motors similarly to an unbalanced Ronin over time. I would recommend having the unit sent back to be balanced when you have the chance.

Thanks DJI-Jamie...  when I get some free time I'll send it back in for them to balance.

timonroecg@gmai Posted at 2016-5-19 14:17
Thanks DJI-Jamie...  when I get some free time I'll send it back in for them to balance.

Wait why are you going to send it back if it is working?

You can rebalance it yourself if you have a 2mm hex tool. All you need is to loosen a couple of the screws and adjust the balance. Done.

Hey CruxisX - if you take a look at the first video in this thread you can see that I balanced the gimbal.  I originally thought that would fix the problem but it didn't, it actually got worse.  From DJI-Jamie's post above "The repair technicians do use additional equipment to further calibrate the servos when the standard Gimbal Auto Calibration does not suffice.".  I suspect that to completely fix these gimbals they not only need to be balanced but there are other adjustments the DJI Techs must do, and also think these are dependent on firmware versions.  My original problem started when I upgraded to the latest version of the firmware.
At this point I'd rather send the gimbal in for repair versus spending more of my time trying to balance it and risking breaking it again.  Also, I didn't mention above but DJI did not charge me for this work (my gimbal was out of warranty by a few weeks).  They paid for the shipping both ways as well.  I do wish they did balance the gimbal but it's back and working so I'm grateful for that.