150A SkyWing ESC mod

[norbique]

I almost finished modding two 150A SkyWing ESCs which I want to use in my scratch built twin cat.
I disassembled the ESC, added watercooling plate between the two FET PCBs, as well as a water block on top of the top FET layer. I added cap banks and I'm going to waterproof the ESC as well. I replaced some of the thermal pads, and put thermal grease here and ther as well. :)

[m4a1usr]

Not critizing your job, cause its looking great. But with the caps installed the way they are you cant see the end that bursts when they fail. The "K" marked end will bulge as a visual warning prior to letting go. Just something to consider.

John

[sailr]

what kind of receiver is that?

[norbique]

John, thanks for the heads up. I don't know how often that happens. If you don't over volt them, they should do fine I guess. I might use a transparent shrink for example.

Jim, it's no receiver. it's a cheap servo tester. :)

[sailr]

it's no receiver. it's a cheap servo tester. :)

Aha!

[norbique]

I forgot to mention, although it can be seen in the pictures, I glued the original aluminum heatsink on top of the water cooling block (using a very thin layer of metal containing epoxy). I was thinking it might help when the boat isn't moving and waterflow stops, the finned sink will still cool the ESC.
I also shortened the lenght of the phase wires to about half of that in the photos. I might shorten the battery leads as well, but I have to put everything in the boat to see how long they need to be.
I'm using 6mm bullets, and I'm about to put spark arrestor resistors inline as well. Any idea what connectors to use for that purpose? What are others using? 2mm bullets? something smaller? The 3.5mm's seem too big and bulky for the job.

[Mel279]

spark_10.jpg

I've connect a spark arrestor like this one, but Im using a 6mm bullets, 5.5mm also ok

[crrcboatz]

can u tell me how u got the boards separated so u could put the brass plate in for cooling? also with the 2 boards sandwiching the brass plate how did u avoid shorts from the top board laying on the brass plate?? I have a 3 layered esc that I would love to do what u have to it. NICE work

[norbique]

Mel,
I'm using 6mm bullets as well. Thanks for the photo. What resistor value/rating are you using? I was thinking 2 ohm 5W or might try 2W, if it doesn't burn up.

Curt,
I wanted to describe the process briefly to you, but it turned out to be impossible, briefly that is. So I ended up describing everything in detail, so others may also benefit from it as well.
Separating the layers is quite easy, you just have to be careful and you need steady hands. But you MUST have good soldering skills!

NOTE: this method has been verified to work on Mystery, Suppo, and SkyWing ESCs, but might work on others as well.
One can easily kill an ESC in this process if not done correctly, so do this mod at your own risk!
(I don't want to be held responsible for any loss/injury that may have resulted from this post. I try to give clear instructions, and to the best of my knowledge.)

Things you will need:
- Dremel like cutting tool
- 80W soldering iron
- 25-30W soldering iron
- good quality rosin core solder
- Soldering vacuum pump
- Solder wick
- Big plastic clamps (1 or 2)
- Extra thermal pads
- Brass plate and brass tubing
- Quality thermal grease
- A set of 1 raster pins
- Some 2.3mm copper wire
- Lots o'patience
- Good soldering skills
- Good nerves
- To accept the fact that you may ruin your ESC in the process! (don't ask how I know)


You'll need a big, (physically heavy, big mass) 80W soldering iron to be able to do quick and effective soldering. Small mass soldering irons loose their heat fast and you end up overheating (slowly cooking :) and killing components on the board. You'll also need a smaller 25-30W soldering iron as well, you need that to solder delicate parts of the ESC, which you would easily ruin with the big iron.

First take off the shrink. At the motor wire end of the boards you can see a row of pins connecting the boards to each other. I cut those pins with a small diamond disc. You cut through the plastic, then the pins, but you don't cut through the plastic on the other side of the pins. You don't cut through the whole thing, the idea is to cut the pins inside the plastic.

Next you have to de-solder the two thick pins (solid copper wire pieces) on the battery end of the ESC. I use the big 80W iron to do this. Once the big pins are removed the boards can be separated gently.

Remove the big electrolytic capacitors as well, and clean up all the solder after them using the soldering wick.

De-solder the wires from the ESC keeping only the RX wire intact! Try to remember where the positive and negative wires go! :) Write down or take photos.

Now comes the hardest part. Cleaning up the tiny pins that were cut earlier. You'll need a soldering vacuum pump, as well as solder wick. But before I can go on with the instructions, I must differentiate between some of the pins found on the ESC. The ESC has a total of 15 pins in that row. Their sequence is something like: 2 + 3 + 2 + 3 + 2 + 3
2's mean the gate driver pins - the delicate parts! Use 25-30W iron!
3's are always interconnected and they are the phase pins. They have the motor wires soldered on.
Using the big iron and the pump you remove the pins and solder from the 3's.
But removing the pins from 2's is easier with the small iron. You can easily damage those with the big iron.
Solder wick is used to clean up remaining solder from the holes, use only where necessary. We don't want to heat the ESC more than it's needed.

Once you've cleaned up everything you can begin reassembling the ESC. You should first inspect the thermal pads, sometimes they have small solder bumps underneath them. I remove those bumps with the solder wick and the iron.
The brass plate between the two PCB layers has thermal pads on both sides. Actually as you will see, the top FET board has it's own thermal pad underneath, so you'll actually need only one extra thermal pad on one side of the brass plate. I also add a very thin layer of quality thermal grease.
Sometimes the FETs aren't aligned nicely, so I just slightly sand the FET cases (320 grit, sanding block) to make them touch the plate nicer. I do this on both FET PCBs.
I always start reassembling by putting in a new set of pins and solder them using both irons as described at the de-soldeing procedure earlier. Big iron for the 3's and small iron for the 2's. I first solder all the pins onto the top most PCB layer, then put the rest of the PCBs together, and I hold them together firmly with a big plastic clamp. You need this if you want thermal conductivity to be maximum between the brass plate and the PCBs. Once you're done with all the small pins you can go to the big pins on the other side. You will probably need to replace those, since the brass plate and extra thermal pad will make the assembly thicker and the old pins won't be long enough. I use a 2.3mm diameter copper wire that fits the holes easily. Cut them to the desired length and solder them in place.

I use home-made external capacitor banks instead of the factory caps, and I solder the those directly on the battery wire as close to the ESC as possible.

I add water cooling block on the top FETs. Also has thermal pad underneath then re-shrink the whole assembly. If you had success, your ESC is now ready to go.

I'll try adding some photos to this thread later, cause it's quite hard to explain certain things without photos.

[Mel279]

norbique

Im not sure, but its similar to those installed on the HW HV 80A esc.

[crrcboatz]

WOW I can solder pretty good but cutting and replacing pins, that is a whole different story. I have my father's large weller soldering iron and my regulated solder station too. Where does one get the replacement pins you speak of in the procees?? My father built his own ham radio equipment but obviously I don't have that skill!!!

[norbique]

I get the pins at the local electronics store. Try radioshack or digikey. It's a 1 raster pin row. Comes in different sizes. 25-50 pins in a row.