M600 Pro A3 Pro LB2. The 1st GPS mast after startup has a Red LED on GPS. The Flight Controler/IMU and #2  IMU are Green  and Blue.
Using the DJI Go App, I can select a different Priority and the 3 IMU's rotate correctly.
As a test... I swapped the physical & connection location of GPS Mast #2 with #1 Red LED.
After restarting , the RED LED followed the #1 GPS Mast and #2 Mast connected to FC workd correctly.
I swapped #1 with #3 GPS Mast and again the RED LED followed the #1 Mast to new location and physical connect to IMU #3.
When connecting wiht DJI Asst 2, the GPS lights continue to indicate #1 GPS Mast as error, but continues to show it in location #1.
Evidently, the CAN1 connections aren't aware of the location plugged intto.... Pluged into FC or IMU3.. shows same location.
This is the area I don't see the method to "reset" to install new.

The M600 Pro is a large craft, I'd lke to avoid sending it in for Service if a repair can be performed.
I am in the process of building a new S1000 with E1200 Proplusion Kits, 17" Props, A3 Pro & LB2.
I borrowed an A3 Pro UPdated pak and swapped the #1 GPS Mast with New GPS Mast.
This caused several red lights and the IMU's all appeared not accepting the new GPS Mast.

Question: What procedure is required to replace a IMU or IMU & GPS Mast?
Do you need to Reset the Flight Controller and start from initial configuration?
Is there a "Reset" that needs to be performed before plugging in replacement IMU / GPS Mast ?

Within DJI Asst 2:
In setting Up the GPS & IMU. It's not specified what value "Y" should be or where it's being measured?

I searched every where and unable to find truble shooting, Diagnostic or Repair procedures for A3 / A3 Pro.

Any updates or procedures would be helpful.

After you have installed the compasses you should go into the garden and perform a (first) compass dance. Remove the propellers first. Then I would not swap anything.
Factory reset is dashboard -> restore.
Best regards,
Wilhelm

WiSi-Testpilot Posted at 2018-9-30 00:15
After you have installed the compasses you should go into the garden and perform a (first) compass dance. Remove the propellers first. Then I would not swap anything.
Factory reset is dashboard -> restore.
Best regards,

Are you referring to after "replacing" one of the A3 GPS/Compass on the mast or in basic A3 Pro setup? I had no issue on setup of A3 Pro, but after 1 failed getting the new to be accepted / recognized by the A3 Pro system; the IMU that had been showing stability of Blue and Green LED became a mixture of RED LEDs. It appears it doesn't recognize the new unit but retains the old unit.

If this is normal when all IMU's and GPS/Compasses blink Red... then great to hear and I'll take her outside for calibration. It just appeared to me that it was in a state where it wouldn't calibrate.

WiSi-Testpilot Posted at 2018-9-30 00:15
After you have installed the compasses you should go into the garden and perform a (first) compass dance. Remove the propellers first. Then I would not swap anything.
Factory reset is dashboard -> restore.
Best regards,

Hi Wilhelm,
Thank you!
Follow-up to 1st reply... assumed it would not have calibrated with all the IMU, Flight controller and GPS Compasses all erratically blinking RED and sometimes Green or Blue. Looked like system was in state of confusion and wouldn't be receptive. But amazingly it did accept a calibration and a reboot seemd to restore the LED's to all Blue / Green without #1 GPS Mask blinking Red.

On 2nd restart to verify operation, the DJIGo app was indicating failure in mismatch Firmware. Connected to DJI Asst 2, reinstalled the FW, Restated and all is Great! Good LED's, FW equal.

That saved packing this big bird up and sending DJI Techs.
I'm amazed the GPS Compass units can't be purchased separately and only DJI Service or purchasing a A3 Pro Upgrade Kit is about the only way to obtain the GPS Compass.

Good to Go!

NO GPS FIX can you help me, please?

@WiSi-Testpilot @DoughcJohn I know this thread is from years ago but I still fly the M600 Pro and I hope you may help me...

My Matrice 600 Pro does not acquire satellites. At the most, I get 5 satellites. I have tried:

• in open field
• placing the drone 2 meters above the ground
• flying in atti mode higher up, let´s say 15 meters above the ground
• waiting long (30 minutes)
  

None of the above results in more satellites. All systems are normal:

• IMUs calibrated and normal
• Compass calibrated and normal
• M600Pro firmware V1.00.01.67
• Lightbridge 2 Air unit firmware V1.1.81
• Ground Controller firmware V1.2.52
• The GPS analyzer app on my iPhone SE shows 12 or more satellites
  

No matter which MC/IMU1/IMU2 I prioritize or use in the DJI Go app, I do not get a GPS fix beyond 5 satellites.

What is not normal looks much like what you reported: 1 GPS module blinks red. DJI Assistant shows GPS1 and GPS3 as normal. However it shows GPS2 during 3 seconds normal then 2 seconds greyed out and this is continuous. However with the other two GPS antennas the drone should still get a GPS fix, am I right?


So I do get 4 or 5 satellites... Just never 6 or more so I can only fly my Matrice 600 Pro in atti mode.


Do you have any clue?
Thanks in advance!!
Rogier

rogiervdheide Posted at 1-4 11:18
NO GPS FIX can you help me, please?

@WiSi-Testpilot @DoughcJohn I know this thread is from years ago but I still fly the M600 Pro and I hope you may help me...

Hi Rogier, I’m happy to help… but currently not at a location or time.
My first thought is a bad GPS puck, the wires sometime get damaged by getting pinched at the base hinge.  I’ll add to conversation tomorrow evening.

You might also want to search through eBay for GPS / Compass units… I was able to purchase some on eBay. Also, creating a ticket at DJI Support, through communication on trouble, I was able to purchase a pair. Replacing GPS puck & mast,  and then resetting the A3 Pro module got it working for me. It helps to Diagnose if you have extra A3 Pro kit, but it’s pretty hard to locate now and often pricey.

I still own 2x M600 Pro, and S1000 with A3 Pro / LB2. Haven’t flown them for a few years… but intend to keep flying them.

Doug

DougcJohn Posted at 1-4 16:31
Hi Rogier, I’m happy to help… but currently not at a location or time.
My first thought is a bad GPS puck, the wires sometime get damaged by getting pinched at the base hinge.  I’ll add to conversation tomorrow evening.

Thanks so much. That all makes perfect sense. I already have reconnected everything under the hood, still that one GPS puck does not behave normally.

The system does not acquire more than 5 satellites, even though two of the GPS pucks work properly. This is enigmatic to me. I have tried in the open, raising the drone, flying it higher on atti... Never it picks up enough satellites to fly in P mode.

I will source a GPS puck, that is not so difficult. A few hundred bucks though. And I will now test what happens when I swap the connectors of puck 1 and 2. Thanks again!!

Update:
- in DJI Assistant everything is blinking green now and the three GPS antennas show steady in the drone diagram
- One GPS antenna on the drone still blinks red though. The two other ones blue and green = good
- IMUs all blue or green = good.

Perhaps someone has a GPS antenna / compass for sale?