What could be the problem... 🤔

I’m trying to install crossfire and feeling like I’m making a hash of it.

Now when I boot up the quad I get the first three rising tones then not the final two.

Can’t spin up the motors in BetaFlight (although gyro is fine).

I’m wondering if I’ve shorted a pad, cause I’m getting a light (see below, and the crappy soldering)

If it ain’t that, how should I go about diagnosing what in the Sam hey is going on?

Yeah I’d redo the gnd next to the scl pad and the lipo wires and go from there.

Looking at that pic. Is there a short on the ARM chip just above the 5V terminal?

Ahhhh! Id not spotted that! Could be. How’d you clear that off…?


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It will be a delicate job but you could try sweeping it down with the soldering iron tip carefully. Failing that a solder sucker should do it. Good luck :+1:t2:

To clean solder splashes on the pins of a chip I’d recommend the use of Desoldering Braid.
Recommend you resolder all the wires onto the pcb pads but try using a Solder Flux Pen on the pads before applying solder you’ll get a better joint, some of your existing joints look dry, prone to breaking off.


To add to @gaz excellent reply I would ditch the lead free solder you are using and go for a lead/tin mix with a rosin core. It’s probably the reason why the insulation on your wires has melted as lead free solder has a low specific heat capacity, meaning it takes longer to heat up and cools too quickly. After using a flux pen on the contacts they should be tinned before you solder the wires to them. You also need to tin the wires. If you do it this way when you apply heat to the contact area and the wire the wire will sink into the solder and the solder will still be nice and shiny once cooled.



Thanks all. I’ve switched to leaded solder, and I’ve got a solder sucker but so hard to catch the solder whilst it’s in liquid state…! I’ll get some braid, sounds handy, and make sure I use flux pen…

Once more into the breach…!

If you can’t get hold of a Solder Flux Pen till after the Bank Holiday try Wickes tomorrow, they sell Active Flux Paste in a pot, see the plumbing section.
It’s normally used on copper pipe solder joints. Apply a small amount of flux to all surfaces to be soldered using a cocktail stick, either new or old joints.

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I use this flux from ebay. It has a brush and you brush it on. Then just touch the legs on the chip with a small soldering tip and the solder bridge should separate naturally. 2 second job. (He says!)
And yes. Lipo leads are a complete ball ache, i agree!