P3P, Gimbal Disconnected, No SD, No Video

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Hello,

I have a P3P with a faulty gimbal.
I have control over the pitch of the gimbal but I see no video in app.
The app says 'No SD'
The app say 'Gimbal Disconnected'.
The Gimbal has no green light on it.
I have tried reformatting but SD in app but it says NO SD.
I have 're-connected' rc and p3p with the app and the small button on side of p3p.
I can't do firmware changes as the p3p cant see the SD card.

Any ideas!?


I note another member called Pnyeguy had the same issue but the thread was inconclusive.
 

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Oso

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Hello,

I have a P3P with a faulty gimbal.
I have control over the pitch of the gimbal but I see no video in app.
The app says 'No SD'
The app say 'Gimbal Disconnected'.
The Gimbal has no green light on it.
I have tried reformatting but SD in app but it says NO SD.
I have 're-connected' rc and p3p with the app and the small button on side of p3p.
I can't do firmware changes as the p3p cant see the SD card.

Any ideas!?


I note another member called Pnyeguy had the same issue but the thread was inconclusive.
Have you already checked the grey cables as was noted in that other thread? Can you post a picture of those cables above your gimbal main board as well as your entire gimbal/camera?

Also, has it been working well until now? I'm asking due to a known weak link that is the gimbal main board of a P3P and the loss of signal between that board and other modules on the AC.
 
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I cant see any issue with any cables. I bought this as 'not working' to replace mine so the seller obviouly has an issue with it. It looks undamaged and in perfect condition.
 

Oso

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I cant see any issue with any cables. I bought this as 'not working' to replace mine so the seller obviouly has an issue with it. It looks undamaged and in perfect condition.
Oh I see. There was more to the story than in your first post. That will save us all time asking about background info.
With that new information (bought as-is) meaning that you don't know any of the background, all we can do is make guesses.
Since you say the cables seem fine, my guess is a bad gimbal main board since it's so common.
 
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Thanks. So, what would make a main board go bad!? And, are they replaceable?
 

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Thanks. So, what would make a main board go bad!? And, are they replaceable?
The gimbal main boards have been noted widely to go bad due to overheating, bad video chip or corrupted FW. Especially in the case of the P3P. We normally advise people to use an external house fan of some type to blow on the gimbal main board during a FW update. There are other reasons they might go bad, but overheating seems to be one of the bigger causes. Bad NAND memory blocks or corrupt code in one of the other components have been reported with P3's which have not been used for a while. Most of the time these issues presents as "No Image Transmission" and modules 8 and 15 showing as "not detected" in the hidden LOG_AB file. In fact, I would have asked you to please post your LOG_AB file if you hadn't already said that your P3 was not seeing your SD cards at all.

Since the boards go bad and DJI does not sell them, they are not easy to get. You have probably seen on a search of this forum or google that people regularly look for them and get them by either buying a new or used gimbal/camera or buying a used gimbal board alone and hoping it is not also a bad board.

Also, as more and more people see this issue some are beginning to have luck with repairing them. quaddamage (member here) has to me emerged as the very best source for help with repairing (if possible) the gimbal top (main) board as it relates to reflashing and overall troubleshooting steps.

Reminder - I'm just guessing that is the problem.
 
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I wonder if its a different issue if others have been able to get the logs off he SD and mine can't see the SD!?
 
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I have exactly the same problem. Have replaced grey cables made no difference. Flex cable to camera has been changed but not by me and not sure if it’s genuine could this cause the fault. Tried to force upgrade by holding in the bind button on boot but doesn’t see the sd card. Have tried 4. The gimbal boots normally and has a green light and will tilt up and down off remote. But no video and disconnected error. Need to work out if it’s cables software or gimbal main board. Anyone got any ideas.
 
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I have exactly the same problem. Have replaced grey cables made no difference.
So the problem is:
- Gimbal stabilizes when power on
- Pitch control on RC works
- No light on gimbal when power on
- 'Gimbal Disconnected' message

If this is the case, then:

- Gimbal has proper connection to OFDM, as pitch control works
- Gimbal has proper power from ESC Center Board, as its motors are working
- Ambarella chip is not powered or does not work, because there is no red nor green light on the gimbal

Either fix the ambarella pipeline on component level, or replace the Gimbal Top Board.

The gimbal boots normally and has a green light and will tilt up and down off remote. But no video and disconnected error.
So the problem is not "exactly the same". The solution above does not fully apply to your issue.

Search for a solution here:
Fix no video feed / black screen / no image transmission / no FPV on Ph3 Pro
 
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So the problem is:
- Gimbal stabilizes when power on
- Pitch control on RC works
- No light on gimbal when power on
- 'Gimbal Disconnected' message

If this is the case, then:

- Gimbal has proper connection to OFDM, as pitch control works
- Gimbal has proper power from ESC Center Board, as its motors are working
- Ambarella chip is not powered or does not work, because there is no red nor green light on the gimbal

Either fix the ambarella pipeline on component level, or replace the Gimbal Top Board.



So the problem is not "exactly the same". The solution above does not fully apply to your issue.

Search for a solution here:
Fix no video feed / black screen / no image transmission / no FPV on Ph3 Pro
I have a green light on gimbal and motors start up so followed the flow diagram as best as i could it says set camera to auto couldn't find this, did it mean set image transmission settings to auto. The diode next to sd slot flashes red green so looks like next step is check between pins on odfm board and gimbal board so that's my job for tonight and will report progress.
 
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it says set camera to auto couldn't find this, did it mean set image transmission settings to auto
This actually means ISO, Shutter, EV settings.
People often have them set wrong and see black screen.
 
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This actually means ISO, Shutter, EV settings.
People often have them set wrong and see black screen.
No joy after checking all connections
This actually means ISO, Shutter, EV settings.
People often have them set wrong and see black screen.
Checked all connections between pins on boards and all seem fine. The diode that flashes green and its not quite red more a yellow is inside the vision positioning module visible through a slot to the right hand corner from the bind button. Is this the correct diode as flow diagram mentions near sd slot but cant see anything near sd slot.
 
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The diode that flashes green and its not quite red more a yellow is inside the vision positioning module visible through a slot to the right hand corner from the bind button. Is this the correct diode as flow diagram mentions near sd slot but cant see anything near sd slot.
The diode on OFDM module underneath VPS module indicates RC link. Should be green if link is OK.

Search through videos featuring the drone and you'll see where the gimbal diode is.
 
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IMG_0772.jpg
Gimbal diode is off. There is 12v at the test pad as is 5v 3.3v and 1.8v at respective pads. Only failed points are on 3.3v on opposite side of board near sd slot it reads 0v not sure if this is relevant. Flowchart indicates problem with voltage regulators or Ambarella chip itself.Does anyone know if the 3.3v pad on other side should be at 3.3v when powered up.
IMG_0771.jpg


On the same track is a component with -3.3v on the left and 0v on the right is that correct or has this failed ?
 
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Gimbal diode is off. There is 12v at the test pad as is 5v 3.3v and 1.8v at respective pads. Only failed points are on 3.3v on opposite side of board near sd slot it reads 0v not sure if this is relevant. Flowchart indicates problem with voltage regulators or Ambarella chip itself.
That's good analysis.

Does anyone know if the 3.3v pad on other side should be at 3.3v when powered up.
You can easily check it. Every switching regulator has a coil at output (the 2.2 uH ones). If the pad is short to any of the coils output, it should be working. If it is from the regulator that only exists in Pro, then it shouldn't as that regulator is missing. In that case the pad will be short to a coil footprint which does not have coil soldered. The coil footprint are two large rectangular pads on right center of your image, below the smaller hole, just next to footprint of the missing regulator chip.

On the same track is a component with -3.3v on the left and 0v on the right is that correct or has this failed ?
I don't know voltages on all components, sorry.
 
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That's good analysis.



You can easily check it. Every switching regulator has a coil at output (the 2.2 uH ones). If the pad is short to any of the coils output, it should be working. If it is from the regulator that only exists in Pro, then it shouldn't as that regulator is missing. In that case the pad will be short to a coil footprint which does not have coil soldered. The coil footprint are two large rectangular pads on right center of your image, below the smaller hole, just next to footprint of the missing regulator chip.



I don't know voltages on all components, sorry.
The pad shows continuity to the left hand smaller solder pad of the 4 from the missing regulator. Am taking this means its relevant to the pro board and isnt part of my problem. Not sure if there is anywhere to go next other than try and find a board replacement which isnt looking great on ebay.
 
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The pad shows continuity to the left hand smaller solder pad of the 4 from the missing regulator. Am taking this means its relevant to the pro board and isnt part of my problem.
Yes, you're right.

Not sure if there is anywhere to go next other than try and find a board replacement which isnt looking great on ebay.
If Ambarella gets power, but still it isn't working, then issue is one of the following:
1. Ambarella chip, its flash chip or RAM chip doesn't touch the board properly
2. Ambarella chip, its flash chip or RAM chip is damaged
3. Programming/firmware of the Ambarella chip (stored in flash chip) is damaged

If it's 1 - you may try reflowing the chips with hot air station.
If it's 2 - Ambarella chip is hard to replace; flash and RAM are easier, but you'd have to buy the new chip not knowing for sure that's the issue
If it's 3 - we don't know how to re-program Ambarella without desoldering the flash chip (with desoldering there are programators, but I never tried that)

For the remaining roads of diagnosis - you may connect to serial interface of the Ambarella chip (to PV via USB-to-TTL converter) and look whether it shows anything. If it shows any messages, they may indicate which chip is faulty; if there's nothing - you still don't know.

If you're very determined, it is possible you'd be able to find a way to re-program Ambarella without desoldering. We don't have documentation for A9, but the one for A7 is public, and it does explain flashing methods. They are likely the same in A9.

Besides that - yeah, replacing the board. Used ones are sold for cheap internally within China, but you need a proxy company (re-packaging company) to send it abroad. I never had enough patience to find such company, and also find the board on chinese-only sites. But I remember this was discussed a few months ago.
 
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Yes, you're right.


If Ambarella gets power, but still it isn't working, then issue is one of the following:
1. Ambarella chip, its flash chip or RAM chip doesn't touch the board properly
2. Ambarella chip, its flash chip or RAM chip is damaged
3. Programming/firmware of the Ambarella chip (stored in flash chip) is damaged

If it's 1 - you may try reflowing the chips with hot air station.
If it's 2 - Ambarella chip is hard to replace; flash and RAM are easier, but you'd have to buy the new chip not knowing for sure that's the issue
If it's 3 - we don't know how to re-program Ambarella without desoldering the flash chip (with desoldering there are programators, but I never tried that)

For the remaining roads of diagnosis - you may connect to serial interface of the Ambarella chip (to PV via USB-to-TTL converter) and look whether it shows anything. If it shows any messages, they may indicate which chip is faulty; if there's nothing - you still don't know.

If you're very determined, it is possible you'd be able to find a way to re-program Ambarella without desoldering. We don't have documentation for A9, but the one for A7 is public, and it does explain flashing methods. They are likely the same in A9.

Besides that - yeah, replacing the board. Used ones are sold for cheap internally within China, but you need a proxy company (re-packaging company) to send it abroad. I never had enough patience to find such company, and also find the board on chinese-only sites. But I remember this was discussed a few months ago.
Tried a reflow first as that seemed the easiest my reflow station is in fahrenheit so brought it up to 230 for 3 mins then 5 mins at 430 with lots of no clean flux dribbled under chips and a tinfoil shield to protect the rest of the board. Not sure of the temp or time hope these were ok. Did the Ambarella chip first then tested but no difference. Then did nand chip wasnt sure of RAM so havn't done that yet. Anyway didnt make a difference so have ordered a USB to TTL FT232RL FTDI Serial Adapter Converter Module for Arduino 3.3V / 5V FU 5060586980603 | eBay to proceed down that rd.
 
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If it's GL300a, then the proper diagnosis is on this diagram:
Fix no video feed / black screen / no image transmission / no FPV on Ph3 Pro
I added a blue rectangle marking where the RC diagnosis starts.

If it's b or c - the diagram would lead to damaged USB board, which is probably not true in this case. Check update logs of the RC - that's the only thing you can do without additional hardware. One of the bottom rectangles on the diagram explains where the RC update logs are on Android devices.
 

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