A few weeks ago I was practicing FPV acrobatics at Devon’s Parents House. Their property is perfect for flying because there are tall tress great for racing around and the somewhat hilly landscape provides a good practice area for visualizing line of sight radio reception (trees and hills block radio waves).
All was going well until I tried a split S maneuver and slammed into their roof. Luckily I crashed close to the edge and was able to retrieve what was left of my Vortex 285.
Back to my workbench, I unscrewed the top board and uncovered the carnage. the M2 ESC wire had been severed and the M4 ESC molex connector destroyed. Both power lines to the front arm ESCs had also been ripped from the power distribution board (PDB).
The hardest part was going to be finding a replacement molex connector for the M4 ESC signaling lines. I emailed ImmersionRC’s support address asking them for the part number or listing of that molex connector. I knew it was a long shot to ask for information like that but hey it never hurts to try. I got a response from Randy saying “Looks like you will need a new pdb.” Wrong Randy, very wrong. I get it, you are a business and need to make money to stay afloat. But I am an engineer!
So off to Digikey I went. I’ll save you the nitty gritty of searching through their catalog, the Digikey part number I needed was A98750CT-ND. The manufacturer is HPI, the manufacturer part number is 1734261-2. The part costs $1.08 on Digikey and took me about 2 hours to figure out. I ordered it and waited.
Here is a photo showing the new part (above) next to the stock molex connector on the left and the destroyed connector on the right. Note the ripped up PCB trace underneath the destroyed connector, more on that later.
As you can see, the new one is definitely not the same part as the original, but it does fit and the solder pads are in the same place, jackpot! I cleaned up the PDB with rubbing alcohol, water, q-tips, and more rubbing alcohol, then let it dry. I also removed the excess solder from the ESC power connector pads.
Ahhhh like a fresh canvas. That ripped up copper trace connects the ground line of the ESC signal molex connector to the ground pad of the ESC power connector. What is really strange is that the trace was split in half on the lower edge of the molex connector and ripped towards either pad top and bottom.
This tells me that the original connector was soldered with a problem, the solder went through the solder mask and made contact between the pin on the molex connector and the copper trace underneath the solder mask. This isn’t a huge issue because the trace and the pin are the same circuit, but even still this should not have happened. The quadcopter works ok, but this is a manufacturing defect that was a result of either a bad top solder mask or too much heat during wave soldering.
Whatever, you work with what you are given.
A quick comparison of all the connectors. From left to right; the remains of the destroyed connector, the replacement, the original connector for the other arm, and whats left of the destroyed connector where it originally stood.
Proof that the pads on the new connector will fit with the pads from the original placement on the Vortex 285’s PDB.
I desoldered the remains of the destroyed connector and replaced it with the new one ordered from Digikey.
Next up was adding a wire to do the job of the destroyed trace.
I just used a small piece of 24 guage signal wire from my box-o-wires and made good solder joints between the molex connector pin and the ground wire of the ESC power line. You’ll also notice the positive red line is soldered on as well.
I also fixed the severed ESC signal line with good solder joints, black heatshrink, and added a nice twist to the cable using the heat gun.
I soldered the other ESC’s power lines and plugged in the ESC signal molex connectors. Everything fits and looks good!