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Old Feb 20, 2012, 01:25 PM
Zr_Flyer is offline
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Joined Oct 2011
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Build Log
120 SR Brushless Conversion - Part 1

I basically followed the MCPx brushless mod setup with a few minor differences. The mcpx uses a .3 Mod pinon (I think) but for the SR 120 we need a .4 Mod pinion. The mcpx guys swap to the SR 120 tail so we are good there.

There are a few different ways the mcpx guys are wiring things up, specifically where they are wiring in the theSteve converter. The easiest and they way I have it for now is to run the blue(-) and Yellow(+) soldered to a jst connector and plugged in where the brushed motor was. The red and white wires go to the servo plug of the esc and match the wire colors of the esc. The esc has a mini servo connector, I had some on hand so I used one to make the connection between the theSteve and the esc. For power the esc needs to be connected directly to the battery leads, the esc uses a walkera Micro Plug. I have some batteries that had the right female connector so I salvaged one and soldered the leads to the battery lugs on the 5-in-1 (this is the only permanent alteration to the electronics).

The current motor is from a walkera V100D. I just drilled some new holes and mounted it. Hard part is swapping the pinion gear. The shaft is 1.5 mm and easy to bend a pinion puller is required. Even then it's no picnic. If you can find a micro brushless without a pinion I'd recommend it.

Todo:
I think I am way over geared, the pinion I have is a 14 tooth and I think it is overworking the motor which is too hot to touch after a few minutes of flight. The motor is a $5 used motor I got on ebay so it might of been overheating before. Now that I know this will work I'll probably buy a better motor. I need to try the resistor mod that the mcpx guys do to see if it smooths out the throttle curve at start up. I'll probably solder everything directly to the 5-in-1 to get rid of the plugs and extra wire.


Parts:
theSteve Converter
Heli-Max Brushless ESC Novus FP/CP HMXM3005
HM-V100D03BL-Z-07: Brushless Motor for Walkera V100D03BL Helicopters (see issues above)
Female Jst (salvage)
Female walkera Micro Plug (salvage)
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Last edited by Zr_Flyer; May 20, 2012 at 03:44 PM.
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