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Mikado Modellhubschrauber . GrandRC . CanoMod

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e-E-Flite Blade CP mCX CX 400-3D > A new hectic Blade glitch story - and a fix
 
 
stealth916
Veteran
Location: Rocklin, CA

So tonight after about 50-60 flights on this thing with the new 4-in-1 and no glitches, I changed out my motor and blades to 3D mode.

I had been flying duration mode with 3s and flat bottom blades.

Anyhow, I decide to hover in the kitchen for a blade tracking check, and before I can even get spooled up - the heli is glitching - it takes off by itself, pings off the ceiling lightly (enough to pack the head cap screw with sheetrock) and then just meanders around - before I catch it and a good whack by the main blades.


Hmmm.... ok so what the F???!! Why did this happen. I check everything over thorough - and try again - and it happens again....

OK - so I grab two 5lb weights to put on the skids so it won't go anywhere - and start again.

By luck - I notice that it happens when BOTH of my hands are on the Tx, and then I touch the lower/back part of theTx to my stomach to rest it before take off - as soon as I touch the lower back of the Tx case to my body after having it in my hands - the heli glitches and spools up. It happens consistently - I can recreate it 50 times. It is as if I am throttling up - the lightest touch to my stomach spools up the heli.

I don't know why this started happening - I had been flying a lot with no problems. I checked my antenna, everything is tight. I check the crystal - all good. The glitching doesn't happen when I shake the Tx, tap the crystal, etc - ONLY when I get enough -or certain parts of my body on it - even lightly.

What I did to fix it:

- I unscrewed the antenna and opened the Tx up
- I grabbed a spare 8" length of 22ga wire
- I loosened the antenna mount, and wrapped one bare end of the wire around it and tightened it up again.
- Then I loosened up the Trainer switch, and I wrapped the other end of the bare wire around the mounting post for the switch - and tightened it back up.
- Put the Tx back together and screw the antenna back in.

So basically - I electrically connected the back of the case to the antenna. I put the Tx back together and tried it all again. The bitch - er uh glitch - was gone.
09-05-2005 Over year old.
 
 
c mark smith
Senior Heliman
Location: Mt Vernon, Indiana

anti glitch fix

I just gotta ask,

what in the world led you to add that particular piece of wire to those particular places ?
09-05-2005 Over year old.
HOMEPAGE  
 
 
stealth916
Veteran
Location: Rocklin, CA

I wanted to ground the front of the case, back of the case, and PCB together. These mount points were expedient because of the screw/nut arrangement of the locations as desribed, to tie off the bare wire. Especially the antenna mount, as it is already bolted to the front half of the case. Without this wire, there really is nothing neutral that is electrically connecting the back half of the case to the front half or the PCB - except perhaps the battery posts which carry current and probably are not directly tied to the front half of the case. The screws that hold the case together are painted and/or anodized - and don't offer a solid ground if they offer any continuity at all.

I am not an electronic EMF engineer and I don't claim to be. But I have seen the inside of enough well designed electronic equipment, to know that grounding all parts of a chassis together is sound EMF engineering. It just 'felt' like the right thing to do, at minimum something that wouldn't hurt. It may have worked or it may have been complete coincedence.

When you look at this thing (the Tx) - nothing inside it inspires confidence - starting with the MADE IN CHINA sticker and moving into the guts, which appear less sophisticated than an old AM transisitor radio from the 70's.
09-05-2005 Over year old.
 
 
k0tbt
Senior Heliman
Location: Eagan, MN

Oops!

After reading your post, Stealth, and looking at my transmitter, I'm slightly puzzled. The front and back case halves are plastic; theoretically an insulator. Don't get me wrong, I'm not an EE either. I do think you stumbled onto a path to potentially solving the glitching problems. Body capacitance might be playing a factor here.

I've not opened up my transmitter to check what you've done yet, well once to eliminate the ratchet on the collective.

Stealth, when you're holding the transmitter with both hands, is one of your fingers touching the trainer switch?

Personally, I think you've found a/the? problem. I don't think you've quite found the universal solution, but you're very close. I'll start to do some snooping in my transmitter and see if it helps me.

Any EE's out there that can help?

Karl
09-06-2005 Over year old.
 
 
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Futaba-RC . A Main Hobbies . Boca Bearings

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e-E-Flite Blade CP mCX CX 400-3D > A new hectic Blade glitch story - and a fix
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