My TP3 and a 1S-3S DarwinFPV board question

[drumgod]

I built this little guy last summer. It's the standard TP3 recipe and I've been pretty happy with the way it turned out:

FPVCycle TP3 frame
Amax 1303 5000kv
Gemfan 3018 bi-blades
Darwin 1-3 elrs AIO
Happymodel Diamond vtx/dvr
Ant cam in an Angry Don "racing" canopy

An accidental disarm with a new radio left me with a folded over USB port and an intermittent power issue that ultimately stopped working all together. I tracked the issue to the interface between the two boards that make up the Darwin FPV aio. I "repaired" it by pinching the board together with my fingers and laying into the bottom power pads with an iron until my fingers couldn't take the heat.  That took care of it for a while...

So, the weather was finally cooperative last weekend and, after a month off, I was able to to get our and fly a bit.  On my second pack I was feeling pretty comfortable working on my pinch grip and started ramping things up and pushing my limits. lol. I was having a blast and hitting some new lines until I clipped the top of a maple. Here's a vid if you care to check it out:

http://www.drumgod.com/fpv/clip120.mp4

I didn't get stuck in the tree... but I did snap an arm and my power issues are back... Does anybody know what the interface between the two darwin board parts actually looks like? I can try the pinch and heat thing again, but it might work better if I knew roughly where I was trying to reflow the connection.

[Pathfinder075]

Calling Dr Lemony.

LemonyLeprosy is pretty much the guru at these types of questions, but it's a bit early for him right now (he lives on the dark side of the planet). He will probably be on in a couple of hours. He also has at least one of those boards.

[mstc]

I believe the power pads on both boards are lined up and just soldered one on top of the other. These look like double-sided edge pads, so you can just add enough solder to bridge them on the side. You can start by soldering up the bottom of the ESC board, that should make it easier to bridge and use a big soldering tip.

[Lemonyleprosy]

I stole this photo from Rob Axel, from the post linked below:
https://intofpv.com/t-darwin-1-3s-aio-f4...ght=Mosfet

I’ve circled all of the connections between the boards. The ones on the right are the main power/ground.

I’d suggest touching up all of the connections to help hold it in place. If need be, you could also use a wire to manually jump the connections between the two boards, or, use a bit of epoxy along the edges where the two boards meet to hold them together, and then apply solder.

Solder from the top side of the aio board, not the usb side. If you fill in the little cutouts on the top board with solder and place your battery wires there, you should be able to get a nice solder bridge between both boards with your battery leads holding them together. I’m not sure if I’m explaining that well, I’m still waking up.

I’d suggest also using epoxy, but obviously not over a pad or component.

[drumgod]

Perfect! Thank you guys!  Your description was perfect Lemony. I have the bat on the large pads right now. I'll have to see if relocating them to "connection" side is feasible. The board is mounted upside down and backwards but, I think there's room to connect to the "bottom".

Sigh. In perfect newbie form, my question has been answered in a previous post.  I need to up my game... I'm getting to where I *have* to repair or build. lol. I'm down to a moblite and a nano baby. I have 6 broken micros and parts for three new...

[Lemonyleprosy]

Eh, we don’t really mind repeat questions here, and you would have been unlikely to stumble upon that photo doing a search for what you needed.

I was only aware of it because I was an active participant in that thread, trying to teach Rob how to replace a dead mosfet.

Repairing and building are just as fun as flying, at least to me.

Edit- if moving your battery wires to the other side of the board isn’t feasible, just make sure you put a nice blob of solder in there on both the positive and ground, and epoxy the edges like I suggested above.

[drumgod]

Well, I attempted a quick fix, in situ. I moved the bat from the large pads to the castellations on the other side/board... I now have reliable power to the FC but it seems like the esc isn't powering up at all now. Well, it's not playing the start-up tune anyway. I still have vbat at the large pads, so something else must be going on besides the main power interface. If I get a chance this weekend I'll pull it apart completely and reflow *all* the connection points.

[Lemonyleprosy]

Let us know how it goes.

Post some clear pics while it’s apart?

[drumgod]

Well, I'm up late and in the right mood to fidget with small stuff. Sorry for the oddly colored cellphone pics... I'm going to have to clean those motor wires up.


The original repair attempt turned out surprisingly solid. It fought me a little getting the bat leads off.


On closer inspection I can see that the internal trace/layer has started to pull up. Couldn't get a pic through the loupe though. The leading corner of the board is visably bent downwards... I dowsed everthing in liquid flux, trying to get it to wick between the boards. I then reflowed the main connections, adding more solder and leads cut from a resistor.


Then I flipped the board over, tied the two halves together and cleaned up the motor pads a bit.


The small connections at the other end looked pretty solid but I reflowed them anyway.


Last, but not least, I tacked the battery leads back into the whole mess.


Surprisingly, with a little wiggling, I was able to get the board to power up on the severely damaged USB port.  I went to open Betaflight to see if it was there... and I it won't open. I was playing around with different kernel drivers under linux, trying to get hardware acceleration working in Gyroflow. I seem to have messed something up. To be continued...

[Lemonyleprosy]

Good job with the resistor leads, that looks solid and clean.

[drumgod]

I realized it was going to be quicker to just reassemble the drone than to get my graphics drivers straightened out. In the morning I soldered the motors back up, fixed the askew iso gummy (derp), buttoned everything back up with another 5 deg or so added to the camera, and took it for a spin.

Video, if interested. This time from the onboard dvr. (dvr was lost with the power glitch on the last video) Much of the same as above but sketchier. lol. The camera angle change feels a weird.

http://www.drumgod.com/fpv/clip121.mp4

The operation seems to have been a success.  I clipped a couple branches and power remained stable. We'll see how long it lasts this time... Thanks guys!

[drumgod]

Well, she's been flying great but the newer FCs I have for repairs and new builds are all ELRS3 and this guy and my radio are running ELRS2.  I fixed my graphics driver issues and fired up betaflight configurator to see if I could update it... Unfortunately, the usb port decided it had had enough and broke off.

Do any of you guys know if the USB pads shown to the left are the same as the usb port used for configuration and firmware updates?

[Lemonyleprosy]

Yup. You’ll be fine to temporarily solder a usb cable or jack on there.

[drumgod]

You da man LL. The USB break-out board that comes with some of the newer Betafpv AIOs has solder pads on the back side...

[ph2t]

He is the man, you are correct drumgod.