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Solved Desoldering tips/tricks?!!

makattack

Winter is coming
Moderator
Mentor
#22
I'd still un-solder or disconnect the VTX, plug a battery in and see what voltage you have on the VTX pin.

I did find a close up on google - they are definitely resistors (black) but too small to read the resistance value. The power part right next to it doesn't come up in any searches that I could find so it's probably some Chinese knock-off PMIC
I believe you're looking at the wrong photo. In post #14, @kilroy07 posted a vendor pic that has two solder pads for selecting the VTX voltage, but those aren't the pads he desoldered / where the blob landed. He was just reusing a pic that was documenting something else, but also included the components in question. Those resisters near the voltage selection pad are definitely black, and probably zero ohm resistors, but I think the components he lost are caps... I would also guess that most of the caps on that board near where those existed are the same value.
 

kilroy07

Well-known member
#23
Sorry about the confusion with the pics... @Brett_N ... I should have made it clear that wasn't my photo....
Here's where the problem is (I'll post it as a thumbnail)
IMG_7793_LI.jpg
 
Last edited:

Brett_N

Active member
#25
Sorry about the confusion with the pics... @Brett_N ... I should have made it clear that wasn't my photo....
Here's where the problem is (I'll post it as a thumbnail)
View attachment 118214

Those are the decoupling caps for Vdd (there are 4 Vdd pins, scattered around to make layout on the board easier) - They are 2.2uF capacitors per my other post. The 2 caps just below the yellow wire on pad DA2 are the same. The ones missing are decoupling for VDD pin 64 and the one on the other corner is decoupling for VDD on pin 48. If you have a tiny tiny set of probe tips for a multi-meter, you can verify that the cap value is correct by probing across the 2 caps over by the DA2 pad.

The ones by the "dot" on the component are decoupling for VDDA and VREF, and are 100nF each

The link to digikey is the correct component.
 

makattack

Winter is coming
Moderator
Mentor
#27
Order placed, $1.60 for parts, $3.95 to ship! :LOL:
haha, digikey stock guy is probably thinking "oh man, what a PITA... he's only ordering two SMD caps... I have to put the little tiny strip with the two caps in a giant bag and in a box that's probably 100x too big for it (but still small enough it fits in the palm of your hand) and mail it just so it doesn't get lost!

Afterall, you could technically tape them to a post card and mail it... heck, you can just stick them to the back of the stamp then past it onto the card to avoid excess tape!
 
#30
IMG_7814[1].JPG
This arrived last week... Not "quite" as bad as you had guessed @Brett_N but for 4 SMD capacitors... Yea, it's kind of crazy!

I didn't do any work on it honestly because I just needed to take a break.... (potentially destroying a $50 flight controller just had me in a funk.)

But tonight... I grabbed my strongest readers, magnifying glass and microscope and fired up the soldering iron again...
And....

IMG_7838[1].JPG
"It's ALIVE!!!" At least it connected in INAV!
Now to get everything connected and see if there is anything affected by my horrific soldering job...
(No seriously, I normally share, but it's just too horrible to share... but it works!)

So, THANK YOU EVERYONE who helped out and offered support/suggestions!!
And let this be a lesson for you kids... DO NOT solder a connector above your flight controller!! ;)
 

kilroy07

Well-known member
#34
I know things like this can easily suck the wind outta yer sails and set you back.
THANKS! Yea... I honestly just had to walk away from it that first night...

I'm pretty excited about having a fixed wing with the capabilities of my old Phantom 2+.
And I like to tinker with electronics a bit and I'm pretty sure the f405 is pretty much an Arduino at heart.
(admittedly with the better/more powerful ARM cpu.)

I might ask for some help from ya with INav, While I fully understand PID tuning for my 3D printers, I'm not really sure why I need to do it here... But, I haven't watched those videos yet either... Next week... I'll look at it next week...
We're doing thanksgiving tomorrow, and I need to focus (and, the wife tells me... Get ALL the planes out of the living room!!!") :rolleyes:
 

PsyBorg

Fly Angry
Mentor
#35
Dont tell me I missed thanksgiving...

I am prone to time loss and thinking today is tuesday when its saturday hehe.

I know exactly squat about Inav other then what they get put in is 99% responsible for all the crap our hobby in general has been under attack for.

Pids are the same no matter what they are used on. I would think in a fixed wing you could probably go with lower level p gains and higher I gains for response to buffeting and shear effects. Not sure where d gains would fit in as any prediction would be too random not like quads where hard changes produce over / under levels of change.

I am also sure it would be slightly different for servos vs motors.

I will suggest super stiff control rods with as little play as possible like enlarged holes and flex. These things think and react fast and those two thing would over work servos for sure.
 

kilroy07

Well-known member
#36
Dont tell me I missed thanksgiving...
Hey man, if you're in the neighborhood, you know you've got a seat at our table!!

Wasn't aware that INAV was responsible for the drone Apocalypse, or are you saying it's the DIY drone crowd that is to blame?
(Inquiring minds want to know... and I promise to use my rig responsible!) ;)

Ah pids for the link between the gyro and bumping the servos, it all makes sense now!!
I've had some experience with the HobbyEagle A-3 series of gyros and once had the gains too high on the elevator... (thus oscillation, probably the same thing.)

Thanks for the help!

Lunch/Dinner will be ready around noon, see you then! (y)
 
#37
THANKS! Yea... I honestly just had to walk away from it that first night...

I'm pretty excited about having a fixed wing with the capabilities of my old Phantom 2+.
And I like to tinker with electronics a bit and I'm pretty sure the f405 is pretty much an Arduino at heart.
(admittedly with the better/more powerful ARM cpu.)

) :rolleyes:
It happens - trust me, I deal with it all day long at work (I'm actualy a motor control marketing guy for Microchip :) )

AS for Arduino - you've got it a little backwards. Arduino is a programming language, the STM32F405 is simply an ARM Cortex M4F processor. Arduino will run on pretty much any processor, from itty bitty little 8-bit devices (the original ATMEGA328 version of Arduino boards!) Up to the big M4F's, and some bits and pieces in between.It will even run on some of the embedded Intel processors, but you're better with Linux in that domain.

As long as there is a bootloader available for the hardware, arduino will pretty much run on it. Then it's just a matter of writing the peripheral mapping libraries

AS for the Phantom 2+, that was basez oin the NazeM flight controller (also by DJI) software embedded in the drone rather than a stand alone unit. You should be able to re-flash it with INAV or an upgraded version of NazeM.

ST "bought" a huge chunk of the flight controller market (well, just about every market for that matter) with thin margins on very competitive devices. (They're propped up by the Italian and French Governments, so they can sell at a lower operating margin!) But, they make nice parts.
 
#38
I've got to give you props for even trying.
If I dropped a blob of solder on an IC like that, I'm guessing I would have not even attempted to remove it. Nice job! I hope it continues to work for ya!