Devo 7E main PCB component ID help

I installed a new P FET given to me by flickerkuu from rcgroups (big thanks!) and my devo is back to perfect working order. Thanks for the help!

Hello guys (sorry to revive the thread),
I believe I have the exact same problem that OP has.

I have just finished 2x3 mod on my 7E, turned on and everything worked fine.
I then performed the nRF24L01 mod (my only module so far), tested all the cables and connections for shorts, everything was good.
When I bolted the remote back, something felt harder than usual, I guess it pressed on one of the new cables.

I then turned on the 7E, the screen light turned on but nothing else.
Seconds after white smoke started to rise, I immediately turned the 7E off and disconnected the battery.

When opening the remote, I found out that the black GND cable (that connects the new nRF24L01 module to the main 7E board was torn and the plastic has melted).
I do NOT know if the GND cable was torn apart at the time of bolting the remote back together OR if the cable melted after turning the remove on (is that possible...?).

Long story short, the remote won't turn on anymore, and the same FET seems to be burnt here as well (image attached).
Unfortunately, my knowledge in electricity is very limited (very, I was following a guide), but I did verify at every step that my soldering was perfect and checked for shorts.

I really hope I can fix that remote (it's brand new, hadn't flown once yet).
Can anyone confirm that this is indeed the same problem and can indeed be fixed by replacing this component?

If so, what exactly should I be buying? (the same link that OP had does not ship to my country)

Image attached (is the FET really burnt? or am I just imagining?)

Fixed images:




Thanks a lot in advance, I will appreciate any help (total newbie here)

Pictures don't work. If it's the pfet that's causing the issues then as the guys recommended earlier, you can bridge it via the 2 holes located directly below using a small bit of wire. I did this and if I left power switch on and unplugged the battery and plugged it back in then the devo would come to life. If it turns out to be the fet, PM me and I'll ship you some spares.

Tnx alot for replying!

I have fixed the images, can we confirm that the problem is indeed identical to the one posted here earlier?
Also, if I bridge the FET and something IS indeed wrong with my setup, won't I fry everything else?

I had an issue with using that tape. It was causing a short. I removed it and used shrink wrap and have since had no issues. As HappyHarry has said, the tape is conductive and will cause shorts.

is that a metallic tape?

I'm going to assume it's this, copper foil tape

why on earth would you use a conductive tape on an electronic device? no wonder you got shorts! either use kapton or even electrical tape but first things first remove that tape!

I see, the gold tape thing must be shortening the lower pins.
Does that mean that the module is fried as well?

I was following that video:

(minute 46)

The gold tape thing should not be used?

I would remove the tape and use electrical tape or heat shrink and then bridge the fet and test to see if the module is working. If all is working well then I'll send you the fet you need.

AcidWord wrote: Does that mean that the module is fried as well?

We can't answer that, it could be or it could be fine and just the wires melted.
First remove the old wires, just snip them to get them all out of there. Second test both things for short- test the devo at several different spots on the ground plane and the + Rail and then test the module. If both of those read open and there are no shorts anywhere go ahead and reinstall it and as mentioned, jumper the power jumpers so that it bypasses the fet and see if everything Powers up.

@royent make sure you mention what powering it with the jumper is doing when you tell people that can be a permanent fix: yes it works to power the devo but turning off the OE power switch doesn't actually cut power, the MCU always has power if the batteries are in, it's a soft switch and it's what tells the FW to save any changes you've made before switching off. You can force a save by changing model files but if you make a bunch of changes and turn it off by killing the power you'll loose those changes if you forget to save it...

Don't know if you knew that and are dealing with it another way (changing files) or if that's news to you but either way, probably best to include that little bit of info when you're telling people that jumping over that fet could be a fix. Just to save them a little more frustration.

Yeah that definitely needs to be mentioned. My bad, I'm super tired and a bit vague when it comes to instructions. I knew it did that but I wasn't making any drastic changes at the time I had the bridge in place so I pulled/plugged the battery as a make do power switch till I sorted my issues and got a new pfet installed.

First remove the old wires, just sniff them get them all out of there. Second test both things for short- test the devo at several different spots on the ground plane and the + Rail and then test the module. If both of those read open and there are no shorts anywhere go ahead and reinstall it and as mentioned, jumper the power jumpers so that it bypasses the fet and see if everything Powers up.

I'm sorry I am really inexperienced in electronics, I'm afraid i'm gonna need the instructions for dummies
Where is the "ground plane and the + rail" on the devo?

I took the copper foil off entirely, tested all the wiring on the module to the 7e board, all still work and no shorts.
I have bridged the 2 holes below the FET, but the 7e still won't power on.

AcidWord wrote: I was following that video:

The gold tape thing should not be used?

seby looks to have his wiring insulated, but even though components on the board aren't so it's still not a good idea imo. if you want to use copper ot aluminum tape for rf sheilding first cover the module and wire ends with either heatshrink, kapton or electrical tape bud

seby looks to have his wiring insulated, but even though components on the board aren't so it's still not a good idea imo. if you want to use copper ot aluminum tape for rf sheilding first cover the module and wire ends with either heatshrink, kapton or electrical tape bud

Thanks for that info, Harry!
I will go without the RF Shielding for now.

royent wrote: Yeah that definitely needs to be mentioned. My bad, I'm super tired and a bit vague when it comes to instructions. I knew it did that but I wasn't making any drastic changes at the time I had the bridge in place so I pulled/plugged the battery as a make do power switch till I sorted my issues and got a new pfet installed.

Hey,
I have bridged the FET and the remote powers (with the module connected) I guess it's good news and that the problem is indeed the FET, it does however display "battery critically low, can't save" (is that ok? battery is on 7.3v).
Is it hard to replace the FET with home tools (cheap soldering iron + claws...)

you shouldn't be powering the 7e with anything more than 6v bud, and it shouldn't be displaying that the battery is too low if it is at 7.3v?

HappyHarry wrote: you shouldn't be powering the 7e with anything more than 6v bud, and it shouldn't be displaying that the battery is too low if it is at 7.3v?

I'm powering it using a 2S LiPo: High Quality Transmitter LiPo Battery 7.4V 2200mAh for Walkera Devo 7E Transmitter

The thing is that after bridging the 2 holes, my remote is not not aware of the battery level, ever, it keep on showing "--" in black and beeping every few seconds saying "battery critically low".
But that's not even the the odd thing, the odd thing is that now both sticks are not working, they always show 0% no matter what.

I have configured the new module in the hardware.ini and managed to bind to one of my quads, only the trim buttons & switches responded, but both sticks are always on 0%.
Could it be related to the FET? or could something else fried...?

I'm really lost here afraid I just killed me new remote...

Please guys, I am desperate

Is it normal for the sticks to always report on 0% (on screen) and the battery level to show "--" (in black) after bridging the mentioned FET?

i don't know bud as i've never experienced this myself, just hang fire till one of the guys who have dealt with this are on the forum again

like i said before though you shouldn't power the 7e with anything more than 6v so it is possible you have fried other components and not just the power switching fet