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Old Apr 22, 2012, 01:41 PM
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Newcastle, UK
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Originally Posted by HeliDrew View Post
Thanks guys, that was it, the batteries were a little loose. I put a folded up peice of paper in before closing the door and it works fine now.
That is good news, pleased to be of help, I don't like to hear of a grounded pilot
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Old Apr 22, 2012, 03:11 PM
Safety : practice & promote!
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I tried swapping out the motors in my grounded S107G today. I wanted to avoid soldering directly to the PCB so I cut the motor wires and soldered the ends of the new motors wires onto them and then put heatshrink tubing around the splice to avoid shorting.

The good news is that my stuttering motor problem is gone.

The bad news is that my heli can barely get off of the ground at full throttle. Giving it forward elevator (e.g. tail rotor) I was able to break neutral buoyancy and gain altitude but that didn't last long. This effect remained even though I would try it on a full charge.

I then tore down the blade shafts, cleaned off the grease that was on them and re-lubed everything with break-free CLP, but I wasn't able to get any better power out of the helicopter.

I finally tore it completely down, de-soldered the motor wires, removed the splice, and soldered the motor wires directly to the PCB. After a full charge, I tried getting it to take off again....but no luck at all.

My only other thought is that the battery might finally be crapping out (it was my original from November 2011). Other than that, maybe the little copter is finally toast....
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Old Apr 22, 2012, 03:41 PM
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Okay, it doesn't seem to be the battery. I removed the original battery and did the external battery mod and tried it with a fully-charged 120mAh 3.7V 14C Eflite battery. I couldn't get very far off the ground but it does appear that the drive gear attached to the inner shaft is no longer holding solid.

In fact, I just discovered that I can hold the top blades still with my hand, spin up the bottom blades and the inner shaft gear is spinning nicely without putting much torque on the top blades.

Time to get a new inner shaft/drive gear.

Or maybe just a new S107G...


EDIT : Anybody know if there's a way to firmly attach the gear to the inner shaft? Does CA glue work to bond plastic and aluminum like that?
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Old Apr 22, 2012, 03:54 PM
NotAnotherMomentLostToSei zures
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United States, MA, Malden
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Originally Posted by RoboHeli View Post

Time to get a new inner shaft/drive gear.

Or maybe just a new S107G...
If you have extra S107 helis/parts, I would attempt to fix it. After all that's half the fun of this hobby Right now I'm doing a complete main frame change over on my V4 and loving every minute of it.

But, if you must,,,...go for a new S107

Mike.
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Old Apr 22, 2012, 04:05 PM
NotAnotherMomentLostToSei zures
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Originally Posted by RoboHeli View Post


EDIT : Anybody know if there's a way to firmly attach the gear to the inner shaft? Does CA glue work to bond plastic and aluminum like that?
Just earlier I was advising a member that CA won't stick to nylon (as in nylon gears). I assume you meant "nylon" and not "plastic" right? As CA will stick to plastic. My Gorilla Glue says "bonds metal"...doesn't specify aluminum. I can't recall using it on any kind of metal...sorry.

I have read about this and is in no way first hand experience.

Mike.
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Old Apr 22, 2012, 04:20 PM
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Thanks Chap1012.

I actually don't have any spare parts right now. I'm so new at this hobby, that this is the first S107G I've had real problems with. I think that this little heli is about to become my first parts donor...

And yes, I assume the white drive gears are nylon.

So, I just spent more time with it and it's definitely NOT the gears slipping. I pulled the gear box out and explicitly tried to identify what was slipping and I was wrong. NO gears are spinning around their shafts. When I stop the gear train, it stops *everything* up to the pinion on the drive gear.

I put in a 25C Lipo into the heli and it took off like a rocket. However, I could only keep it flying for about a minute or so before once again it couldn't stay in the air.

Maybe I got a bad set of motors? I dunno. Maybe the PCB has a bum set of motor drivers now. I'm just not sure....
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Old Apr 22, 2012, 04:44 PM
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Oslo Fornebu, Norway
Joined Jun 2003
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Can someone check their helis shunt resistors ?
Mine has 0.12 Ohms which I feel is high.
I suspect it snuck through QA with wrong values.
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Old Apr 23, 2012, 04:28 PM
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How much current does a syma need to hover?
My 9026 uses 1.8 amps! It weighs 43 grams.

I am quite sure it's a overcurrent issue.
Could my two motors be swapped sothey run inefficiently?
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Old Apr 23, 2012, 04:49 PM
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United States, WI, Merrill
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Originally Posted by RoboHeli View Post
Thanks Chap1012.

I actually don't have any spare parts right now. I'm so new at this hobby, that this is the first S107G I've had real problems with. I think that this little heli is about to become my first parts donor...

And yes, I assume the white drive gears are nylon.

So, I just spent more time with it and it's definitely NOT the gears slipping. I pulled the gear box out and explicitly tried to identify what was slipping and I was wrong. NO gears are spinning around their shafts. When I stop the gear train, it stops *everything* up to the pinion on the drive gear.

I put in a 25C Lipo into the heli and it took off like a rocket. However, I could only keep it flying for about a minute or so before once again it couldn't stay in the air.

Maybe I got a bad set of motors? I dunno. Maybe the PCB has a bum set of motor drivers now. I'm just not sure....
Quote:
Originally Posted by KreAture View Post
How much current does a syma need to hover?
My 9026 uses 1.8 amps! It weighs 43 grams.

I am quite sure it's a overcurrent issue.
Could my two motors be swapped sothey run inefficiently?
You can't reliably swap your main motors as they are built to turn in opposite directions from each other. I would order a new set of clockwise and counter-clockwise main motors and a tail motor assembly as well just in case you are getting some weakening there as well. The motors are pretty cheap and can be gotten from Amazon.com, Ebay, Newegg, and a bunch of the free shipping chinese online outlets. You will need to do some pretty fine soldering, but the motors for a Syma S107 are not prohibitively expensive.

John

PS if you are ordering from a free shipping China or Hong kong outlet you might as well add blades, a new shaft maingear assembly and anything else that you might find at the site you are using.
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Old Apr 23, 2012, 05:01 PM
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Quote:
Originally Posted by jgestner View Post
You can't reliably swap your main motors as they are built to turn in opposite directions from each other. I would order a new set of clockwise and counter-clockwise main motors and a tail motor assembly as well just in case you are getting some weakening there as well. The motors are pretty cheap and can be gotten from Amazon.com, Ebay, Newegg, and a bunch of the free shipping chinese online outlets. You will need to do some pretty fine soldering, but the motors for a Syma S107 are not prohibitively expensive.

John

PS if you are ordering from a free shipping China or Hong kong outlet you might as well add blades, a new shaft maingear assembly and anything else that you might find at the site you are using.
Umm, you are aware that this is a brand new heli?
It has run 3 packs and never flown properly due to it's controller cutting power to motors all the time.
I was supposing my motors are already swapped wrong so that they turn the wrong way. This would make them suck extra current and may trigger the overcurrent detection.

I shorted out the sense-resistors to test my theory and it does not cut out.

If someone has a similar heli (9026) and could check the colors of the wires from their motors I may be able to verify this.
My front motor has white/black and my rear motor has red/blue.
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Old Apr 23, 2012, 05:12 PM
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I checked the syma motors and it seems the white/black is clockwise rotation seen from motor and out the shaft and due to the idler gear in the syma s107 it has same direction as looking down on rotor. Comparing with my heli I see my motors are indeed swapped, but it has single-stage gear making the rotation correct.
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Old Apr 23, 2012, 07:21 PM
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@jgestner : just to complete the picture, I had just swapped out both motors in my S107G because one of them was overheating and going bad. The bad one was twitching like crazy when it was in there. With the new motors, the twitching stopped but now the heli couldn't even get off the ground. At this point, given that I had new motors, my next thought was that maybe my PCB is flaky (or else the new motors were also bad...?)
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Old Apr 24, 2012, 12:38 AM
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I have been moding the s107 for a long time now and have modifyed and sold 35 helis. If you can't get of the ground you should check the battery. the CB is somthing that wont go out inless you solderd the wires rong or hit one of the terminals with the battery ground or the live wire. when charging a bad battery the charging light will go bright but it will not hold a charge. You will have now power to the motors. If you have a bad CB the the giyo is the first this that go's out. Also on the bad CB the tail will quiver or the tail motor will not work at all. For my self I would rebuild the heli. I would not rebuild it to stock specs. The speed of the s107 is not to good out of the box.
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Old Apr 24, 2012, 09:17 AM
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Hi SAF_Dogface, yeah, I did check the battery. In fact, I did the Eflite battery connector mod and I tried a 14C 3.7V mCX Eflite battery with it as well as a 25C 3.7V Thunderpower mCX battery. It couldn't get higher than ground-effect level with the Eflite battery (just like its own stock S107G battery) and I could only get about a minute or so of flight with the 25C battery before it pooped out at ground effect level again.

No idea what might be wrong at this point. I'm getting another yellow S107 as a fully functional replacement (gotta have enough helis to fly with my kids!) and then I'm going to use this old one to experiment with modding.
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Old Apr 24, 2012, 04:26 PM
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I disabled the current shunts on my 9026 and I can now fly continously with no power cutouts.

A full charge only hovers in place for 2 minutes though suggesting that the current draw is excessive and that the over-current sensing is not wrong, just unfortunate.
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