Phantom 3 Pro gimbal falls asleep after drone is turned on / no signal

[Infinite_parts]

You have USB-to-TTL? Solder its GND, RX and TX to test pads on the gimbal board.
Also solder cables to 5V and GND test pads

Sorry if this sounds stupid but since I am quite fresh in micro soldering and totally newbie in this programming surgery I'd better ask in public and maybe this will help others like me as well.

Today I took that board in closer look again and I see there are more TX, RX, GND, 3.3V pins than I notice before (with quick overview). I am soldering those USB-TTL pins always the same (as it was showed post by @SunsetCatcher and @quaddamage - but now I want to understand, all those pads with same name are equal in value or different pads are for different use?

For example:
3.3VD pad & A9S_3.3VD pad - plays the same role or different?
URAT2_TX & 368_UO_TXP - these are for?

More I look on schematics, more I learn! More I learn.. more I ask questions to learn more!
Thanks guys.

 

[quaddamage]

Today I took that board in closer look again and I see there are more TX, RX, GND, 3.3V pins than I notice before (with quick overview).

The known pads are explained on the usual wiki:
o-gs/dji-firmware-tools

(pins are pointy, pads are flat)

I am soldering those USB-TTL pins always the same (as it was showed post by @SunsetCatcher and @quaddamage - but now I want to understand, all those pads with same name are equal in value or different pads are for different use?

The pads were named by humans. Simply think how you would name each line, and you will probably guess correctly.

Like all the VD are "Voltages for Drains (aka MOS ICs, various digital integrated circuits).
U will usually mean "UART serial comm. interface" and in this protocol there's receive (RX) and transmit (TX) line.

3.3VD pad & A9S_3.3VD pad - plays the same role or different?

If it is not clear from existing schematics, then take a multimeter and measure.
But if I remember correctly, all the outputs of DC/DC converters are already mapped.

 

[Infinite_parts]

Boys and Gals!

I've got new gimbal (pre-owned) for P3X.
Can you please advise, if I will not unmount whole camera part (with flat ribbon cable) from Gimbal top board and will mount it to the new top board, what is your expectations? Will that camera work or I have possibility to damage that new board again (because of firmware difference in camera and top board)?

Next I am curious about:
1. Will camera settings will be updated according to the board settings (if it was taken off from board with different FW)?
2. Is it possible to damage the Top Board or flex camera cable by touching some connectors (make short circuit)?
3. Once (in the very beginning) I remember I was putting flex cable inside the top board connector and I saw small tiny spark - any idea what could it damage then?

Cheers guys.

 

[quaddamage]

if I will not unmount whole camera part (with flat ribbon cable) from Gimbal top board and will mount it to the new top board, what is your expectations? Will that camera work or I have possibility to damage that new board again (because of firmware difference in camera and top board)?

Firmware differences may prevent you from seeing image, but everything else should work.
Definitely this won't damage anything. Camera with gimbal is a legitimate replacable part. Only iPhones have a special mechanism of checking serial number in each of its parts, all "normal" devices have modules for the purpose of allowing to replace them.

1. Will camera settings will be updated according to the board settings (if it was taken off from board with different FW)?

Not sure what you're asking; after connecting the new part, you should update firmware on camera to the version which rest of the drone uses.

2. Is it possible to damage the Top Board or flex camera cable by touching some connectors (make short circuit)?

You want to make a short by "touching"? Like, with your hand? Sorry, you're not as conductive as you think. Human body can only short high voltages, above 70V. You will not get more than 16V anywhere within the drone. By touching, you can oxidize connections (clean with alcohol if that happens), but you won't short anything.
But if you short something with a metal tool, and you will select wrong lines (ie. short 12V power input with 3.3V data line) you will fry a chip.

3. Once (in the very beginning) I remember I was putting flex cable inside the top board connector and I saw small tiny spark - any idea what could it damage then?

If you had ESD charge on you - it could've damaged anything, ESD charges are very high voltage. If you sometimes get charged anywhere near bare electronics, you need to wear anti-ESD bracelet.
If that was not ESD - you either shorted power pins or motor control pins.

 

[Infinite_parts]

Firmware differences may prevent you from seeing image, but everything else should work.

If I have a board which does not show image (no image transmission signal) in DJI app and it has (latest FW on it) - and it does not read the sd card and does nothing when attached to drone. And then I have board which has lower version of FW but I want to swap cameras (just to have that exact camera on that working board), should I then flash it and try to update with some FW via SD card - will it do the FW update for board and camera during the process?

Why I ask..
Because from one side I want to put that camera from one board to another but from other side I am afraid it will cause some image error again and in worst scenario something more will happen.
I need that drone to be working and filming tomorrow therefore I am bit in doubts should I replace those cameras or better leave that newly installed board with it's camera and leave that non working for other projects together..

 

[Infinite_parts]

You want to make a short by "touching"? Like, with your hand? Sorry, you're not as conductive as you think. Human body can only short high voltages, above 70V. You will not get more than 16V anywhere within the drone. By touching, you can oxidize connections (clean with alcohol if that happens), but you won't short anything.
But if you short something with a metal tool, and you will select wrong lines (ie. short 12V power input with 3.3V data line) you will fry a chip.

I believe I was trying to put that flex cable in sockets (on top board) and touched some pins with screwdriver or pliers that day when I saw that spark at the touching point. I believe it was not connected to any power source then (as far as I remember) - if it was then it could be multi-meter with 9V battery only.

 

[jiminyfixit]

WOW! This is the most detailed and comprehensive technical post on this subject I have ever read. You guys are WAY above my knowledge of coding and understanding the complexities of these fussy electronics and only peaks my interests in being able to solve some of the issues a lot of us "Pilots" have encountered with gimbal issues. I have been repairing P2V, P2V+, P3Pro/A, P3s and the P4 cameras for a long time and have accumulated dozens of "bad" main circuit boards that have issues ranging from "good gimbal with no video" to "limp gimbal", as infinite_parts mentioned. Most of my P3Pro boards have good gimbal with no video transmission. Is there a way to fix this?
Cheers,
Jim

 

[quaddamage]

I believe it was not connected to any power source then (as far as I remember) - if it was then it could be multi-meter with 9V battery only.

Multimeter supplies very low voltage, can't do sparks. Probaby ESD then.

I have been repairing P2V, P2V+, P3Pro/A, P3s and the P4 cameras for a long time and have accumulated dozens of "bad" main circuit boards that have issues ranging from "good gimbal with no video" to "limp gimbal", as infinite_parts mentioned.

If your shipping cost to Poland is not too high, I'd accept some sample boards to take a look.

Most of my P3Pro boards have good gimbal with no video transmission. Is there a way to fix this?

Follow the graph:
Fix no video feed / black screen / no image transmission / no FPV on Ph3 Pro

 

[Infinite_parts]

If your shipping cost to Poland is not too high, I'd accept some sample boards to take a look.

I could ship my boards to you as well, would you be interested to take a look on them as well?

 

[quaddamage]

I could ship my boards to you as well, would you be interested to take a look on them as well?

Assuming you mean one way trip - sure, why not.
If you'd like me to fix them for you - you would probably be disappointed. I am looking at such things on some evenings when I have few hours free. This does not happen often. Plus I don't like fixing things for other people, because they tend to come back with various claims - asking me for "support". I don't do that.

I can take some boards for a promise of sharing all my research - like I did with the "no video" fixing diagram, or NAND replacing description. But fixing for money is not my thing.