So I had a soldering mishap and took several pads off an FC.  The FC uses SPI ELRS and uses the dipole contrary to the below diagram.

The pads happened to be the ones for video.  Is video out/in mapped to say uart2 tx/rx?  Could I remap to uart1?  I think the smartaudio pad is still intact, but is mapped to S5 on the diagram.  is that a soft serial?



On the diagram I kind of messed up the five pads for video.  Three are possibly salvageable.  See attached image of the damage.



My plan if possible is to use SA from it's defined pad, remap Video in/out to UART1 and grab power from somewhere else.  I just want some clarification on whether that will work.

Thanks.

Unfortunately video in and out cannot be remapped as far as I know as they physcially run to the OSD chip. However if you are willing to forgo OSD, you can still use your FC or use a digital VTX.

But question is how did you strip those pads. Usually that is from too much heat, but by the looks of the solder it kind of looks like temperature was not high enough? What tip were you using, and how long did you leave the iron on the pad?

Edit : However you can potentially solder to the OSD chip or the components along the trace, Lemony would probably point you along the right path if he was here, but that nano soldering requires some serious surgical skills.

I tried to do something stupid. I've seen people throw down a blob of solder and then spread it across pads. So I had a blob of solder that was bridging two pads and tried to spread it and yes I had a ton of flux on the pads and general area. :/ I won't be doing that again. It might be the flux as well.

So the solution is (i'm guessing) to send the lipo voltages to the radio instead of goggles, which negates the vast majority of what you need OSD for. If this was some major. This build is a 1002 2S. I can live without OSD on it, I won't be flying it miles away. As long as I can get the lipo volts to the radio and have it trigger a land now audio file when it hits 3.55V, it will be fine.

it looks to me like you can try to scratch the trace gently next to the broken pad. solder them right above the pads. you might see if its an option from eye.


i couldnt find the thread about osd chip layout so far, it might be named badly bymyself. i believe snow provided it, i was able to solder video cable next to the osd chip, it worked well foe me

There are many different methods/tips/tricks for soldering and guess everyone will have their recommendation. But best to try new ways on a test board first to see if it works for you.

For tinning those tiny pads, I will apply only a drop of flux, then solder onto a pencil tip, and touch the side of the tip where the solder is hanging to the pad for just a second. That should be enough to tin it nicely. On heavier pads, it may require solder to be applied to the pad at where the iron is touching.

Once you have bridge pads, then chance of damaging pads is greater. If there is enough space, applying flux and running the iron between the pads will often unbridge them, but if you have a huge blob then probably not.

Yeah it was a bit of a train wreck after I finished doing the connectors for the motors. My hands were like someone with Parkinsons, even though I took no meds today nor drank any coffee. I should have given up but it was like the last 5 pads that needed tinning. You live to learn.

Lemony mentioned about electrically conductive glue, some time back. Is it feasible to cut out a small fleck of copper or liberate one from a broken FC with a scalpel, then solder the wire to it and glue it to the pad? Or maybe skip the copper and glue directly to the pad.

Bro, just look through a magnifying glass where the tails from the torn sites go. Perhaps they are on SMD components. You only need RX, TX and maybe CAM. Solder the wires directly onto these SMDs.
Yes. I looked at this FC and see that it can only be difficult in this place with the GND pad. Everything else goes to the ends of the SMD components. GND you can take directly from the battery negative.5V can be taken from anywhere. At least directly solder to the pads of LEDs or any UART or anywhere where 5V is written.
For small soldering I use SMD paste. There is flux and solder. I apply it to the contacts with a toothpick. It turns out very neatly and there are no huge snot.

I just had a look at the VI pad area for the trace, but it's non-existent as far as I can see, with 25x mag glasses.

I only really need to know the voltage for this quad. It's going to be a 2S only. So I can set a cell voltage alarm of say 7.3V on the radio and that gives me 0.3V to come in and land while still putting down at roughly 3.5V like I normally would. AFAIK it does send telemetry, or at least my Meteor85 (same FC) did.

I believe ELRS does have voltage in telemetry (you can set it to pack or cell in the preset) just detect sensors if you don't see it on your model. You can add that to your radio alarms or have it called out on a switch. That is probably the best solution to get flying.

If you did want to make a project out of the board though, not sure conductive glue or putting on a pad would be the way to go. If you can reveal any part of the trace or the SMD component it runs to, get the finest gauge wire you have and try to get it soldered onto that spot. It will likely be a very weak joint, but then apply glue on it to secure it onto the board, and voila you get back your connection. But OSD chips or their diodes are sensitive to heat, I've burned out a few OSD chips without even lifting a pad so be prepared for that too.

Probably not worth trying when i can get the basics from the ELRS. Better to appreciate it flies, assuming it flies. Better test that first.

Just look at the copper wire.

I've been soldering for a long time. I make all my home hi-fi myself. That’s why I respect my soldering station, he respects me, and we’ve been on friendly terms for a long time. I constantly come across devices that someone has damaged and just look at the wires.
I showed this because nothing can help this deceased. During the flight, the UFL connector of the VTX antenna fell onto the motor contact pads. How the Avatar survived while I was looking for him in the grass, I don’t know.

Unfortunately that level of soldering prowess is beyond my level. I solder with hands that shake like your average person with Parkinsons. Even when i omit medication and avoid caffeine the problem is not fully dispersed. That is some of the reason why this happened. Doing really fine work is a no go for me. i can barely hold the iron tip on a pad as it is. If I solder in the first two hours after I get up and take no medication nor drink any coffee I can usually get a few pads done. After that it's back to the shakes.

If you think this is bad, consider it took me nearly 90 mins to put 4 motors on a whoop frame, ie, screw them down and a further 45 mins to plug the 4 connectors into the FC.

19 years ago when I was at Uni, I could do micro electronics and often did as part of my IT degree, but nowadays it's real hard work to do it.

For the Video In issue, below is a link to the post showing an alternate point on the board that you need to solder the wire to. If you want to try this you will need to locate the junction point between the 0.1uF and 75Ω resistor shown in the red circle and then solder a wire to that point. If it's not easy to see the traces on the FC then a multimeter will help you to trace the 0.1uF capacitor from pin 22 of the AT7456E OSD chip to that capacitor, the other side of which you would need to solder the wire to...

https://intofpv.com/t-remap-cam-input-to...#pid122649

Thanks for that Snow. It looks like if I try this I will have to solder directly to that pin.

(28-Nov-2023, 10:28 PM)Pathfinder075 Wrote: Thanks for that Snow.  It looks like if I try this I will have to solder directly to that pin.

Not to the pin of the OSD chip. It's the junction point between the 0.1uF capacitor and the 75Ω resistor you need to solder to. So you will be soldering to either one end of the capacitor, or to one end of the resistor (which will both be linked together by a trace on the FC so it doesn't matter which you solder to - just choose whichever looks to be the easiest).