Is there a Quark 125B thermal problem? - RC-Monster Forums

BrianG · 11.30.2006, 06:00 PM

Yeah, the Neu is larger in diameter and is a different class of motor altogether really, but I was comparing rough KV and can length values...

zeropointbug · 11.30.2006, 06:27 PM

BrianG, so i popped off the power input end of the Quark and looked inside, pretty neat looking for sure. So did you say you would need a 3mm slab of Alum./Copper if I replace the two thermal pads/slab? What is actually holding the whole circuit to the case? Is it purely the thermal pads there? If i were to do this, i would be persuaded to completely seal the ESC right up to make it basically waterproof, and keep dirt out.

If i were to just attach the Quark to an upper aluminum chassis brace that would have alot of thermal mass and heat dissipation capabilities, would i even have to bother with making the thermal adhesive mod? Because there would still be a large temperature differential between the transistor surface and the outside of the case. I like to make things the best i possibly can, and quality is my name. ;)

Would you have any suggestions for using to seal all the holes in the ESC that is not conductive and that is thick applying, such as Silicone Caulking? I think this would work too.

Cheers

BrianG · 11.30.2006, 07:23 PM

Yep. The existing slab is ~2mm thick with two pieces of thermal pad (~.5mm each) for a total of 3mm. If you remove the pads, you remove ~1mm of thickness and then the caps prevent the FETs from sitting flush on the case. And yes, the thermal pads are what holds the whole circuit to the case.

I suppose you could waterproof it while you're there anyway. You'll have to use some material that won't weaken or get soft when substantial heat is applied, that won't get brittle after time, and can endure the vibrations and jarring. Maybe epoxy may be a better choice?

You can do whatever mod that makes you feel good. :) I just had good luck with what I did, but I'm sure there are other ways to get the same (or better) results.

Good luck!

jhautz · 11.30.2006, 07:51 PM

Quote:

Originally Posted by BrianG

I suppose you could waterproof it while you're there anyway. You'll have to use some material that won't weaken or get soft when substantial heat is applied, that won't get brittle after time, and can endure the vibrations and jarring. Maybe epoxy may be a better choice?

Shoe Goo ???

zeropointbug · 11.30.2006, 10:24 PM

I think Silicone would be perfect then, once it cures it's then almost the consistency of the silicone wire insulation (prob more flexible).

Also, are you sure you have to unsolder the motor wires? Can you not slide the top cover left off of it? Where exactly is the cap. near the esc button?

BrianG · 11.30.2006, 10:30 PM

jhautz: I tried Shoo-Goo on something else and it tends to get brittle and seperate from the thing it's trying to seal. I would think something flexible, yet heat/water/motion resistant would be better IMO as long as it bonds well.

I unsoldered the wire simply because it looked easier. You might be able to work the end off without unsoldering, I don't know. I guess you'll just have to try it. :)

The caps are on the power wire end (since that is where they are used).

zeropointbug · 12.01.2006, 01:35 AM

BrianG, i tried taking the cover off without unsoldering the wires, i couldn't get it to come off. So i unsoldered the wires, and slid it off and noticed that the only thing stopping you from doing it the other way is the little see-threw plastic window for the LED's, it hits a little IC beside it.

Anyways, i go it all apart, except for taking it off the case. I notice that there is two alum. slabs one on both side of the bottom circuit board, and it looks like they are the same FET's ???!!! What!? Do you know if this is true? Or are they for something else? CHeck the pics, if they are the same FET's then maybe all they need is some heat spreading? And the thermal pad is just to attach to the case? It also doesn't really look like the pads are .5mm, they look thinner than that, maybe .3mm? I don't know... I don't want to take it apart yet, i don't have Thermal Adhesive at the moment, i'll pick up some Arctic Silver stuff when i can.

So is there two layers of FET's on the two sides of the power board?