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Old Jan 09, 2011, 11:35 AM
MARCOELDRAGON is offline
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Problem with Grayson Hobby Super Mega Jet V2


I just recently purchased a MPX Funjet and SuperMega Jet V2 Combo
from Grayson Hobby. Started Construction Friday. Got all the electronics layed out and assembled. Now the problem. The motor will not turn under power. It just jiggles back and forth no matter what combination I use to plug in the motor leads. So I tried the motor on two different aircraft that I know everything works correctly on, a PZ Stryker and a Parkflyers Jumjet. The results were the same, the motor just jiggles back and forth without spinning. I then tested the Grayson ESC in the same two aircraft and even to the motor on my Blade SR and the ESC worked fine. I have double checked every solder connection that I have made even though the ESC tested fine on 3 different motors. Should I check the solder on the Super Mega Jet bullet connectors? Kind of afraid to do anything at all to the motor for fear that Grayson will blame me for it not working.
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Old Jan 09, 2011, 11:57 AM
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Looks like you did everything I would have done and it does sound like a bad bullet connection on the motor. If you are sneaky, maybe you can carefully heat up the bullets with a pencil torch to re-melt the solder, then re-shrink tube it. Hopefully the shrink on it is all black so don't have to worry about matching it for a return.

However, I wonder if there is a chance they didn't strip the enamel on one of the motor leads?
Get out a test meter or continuity tester (light bulb and battery will work) and see if you can id the bad connector, this will atleast allow you to focus on just one.
Old Jan 09, 2011, 12:23 PM
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My money is on a bad connector joint... but just out of interest... are you sure your mounting screws aren't too long (and hitting the windings).
Old Jan 09, 2011, 01:23 PM
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As indicated, that's classic for a bad conncetion - anything from a poor solder joint to a broken/shorted wind in the motor.
DO NOT persist in trying to make it run > you WILL fry your ESC. It should run IMMEDIATELY or you need to find out why not.
Old Jan 09, 2011, 03:02 PM
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First thing I checked was the mounting screws and they are fine. Sent a PM to Lt. Smash from Grayson and he replied promptly and told me to try the bullet connectors and sent me a RMA form. Gonna give the connectors a try. Thanks to all for the quick input.
Last edited by MARCOELDRAGON; Jan 09, 2011 at 03:32 PM. Reason: Smash not Crash
Old Jan 09, 2011, 04:18 PM
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Don't worry, Basil (Lt. Smash) at Grayson will do the right thing by you!
Old Jan 09, 2011, 07:02 PM
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This is just giving me more time to do this build completly right and get more stick time in on the Stryker EDF I built over the Xmas holiday. Recently came back to flying fixed wing AC after 5 years of Helicopter only. The more stick time the better before I get the FunJet in the air.
Old Jan 10, 2011, 06:03 AM
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I can almost guarantee you have a bad solder joint on one of the bullet connectors. i had the exact problem with their "Disposable Foamy Sport" combo a few weeks back. I just swapped and re-connected til I determined the bad connection, resoldered it, and it worked fine.
Old Jan 10, 2011, 07:02 PM
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I had the same problem with the same motor. Switched out the faulty connector and all is well.
Old Jan 10, 2011, 08:46 PM
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thanks to all for the info. Have to play nurse to sick GF today, will try to resolder Tuesday and post how it goes. God I hate soldering.
Old Jan 10, 2011, 09:16 PM
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Do some searches on soldering in Youtube and the like.
Gets easier with practice.
A couple years ago I couldn't solder worth much at all. A couple days ago I helped a friend replace 2 bad capacitors in a PC motherboard-a first for me! It works!

I saved his fridge from going to a landfill too. Most fridges are now controlled by a circuit board. His 'fried'. The repairman said he could only replace it for something like $400-company policy: $100 service call, $100 labor, $200 part. Turns out to be a fried relay joint that took 2 minutes to re-solder and was dead easy!
To the repairman's credit he pointed out the problem and was frustrated that it was the company policy. We tipped him $20 for his info he didn't need to provide. Kinda sucks, eh?

I also soldered a fuel relay on our Honda. That would have set me back $150. Again, quite easy once you know how to solder.
Old Jan 10, 2011, 10:14 PM
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My Grayson Hobby motor (not the mega jet, a smaller one) did the same exact thing this afternoon. I found this thread and decided to double-check all of the bullet connectors. One pulled right off - the wire had broken at the connector from bending too much. Re-soldered all of them and now the motor works great again.
Old Jan 11, 2011, 06:02 AM
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My first solder jobs ever were replacing 7 tail motor on my blade SR. Had to do a lot more when building the Stryker EDF. About the same time I switched all my batteries and ESCs over to EC3 connectors, that was a chore that I put off for months. Now I've done the whole power system for this FunJet. I'm getting better at soldering and it is a useful skill, but I still hate doing it.
Old Jan 11, 2011, 03:16 PM
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Soldering bullets on motors and esc is the easiest for me; I just use a propane torch (or the gas burner on the stove when the wife isn't home), holding it with pliers I heat the entire connector, melt in solder (and flux) and insert wire, done.
Old Jan 11, 2011, 05:26 PM
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Pleased to report all is well again. Heated up all the bullets until the solder melted pulled the wire out added a touch more solder to each and shoved the wire back in. Tested and the motor runs fine now. They all looked fine so not sure which one was causing the problem.


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