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Blowing up the ESC - Walkera 5-4

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Blowing up the ESC - Walkera 5-4

Old 09-02-2007, 09:57 AM
  #1  
Feric Jagger
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Default Blowing up the ESC - Walkera 5-4

I just discovered what happens if you plug the motors into the crappy Walkera receiver module the wrong way round.
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Old 09-02-2007, 11:08 AM
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jtspin
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Default RE: Blowing up the ESC - Walkera 5-4

LOL!

Do the 5-4 motors have a diode (black cylindrical thing with a silver stripe at one end) soldered across the terminals? If so, a good 4-in-1 won't survive either if you plug the motor in backwards (ask me how I know).

-JT
Old 09-02-2007, 11:17 PM
  #3  
Feric Jagger
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Default RE: Blowing up the ESC - Walkera 5-4

JT

I just compared my Walkera 4-1 with the bits of my 5-4. I don't know much about electronics [except how to blow things up]. However, I now see that my 4-1 motor does have a diode [reference "5819 GW"] and three components that look like brown lentils [reference "104"], one connecting the two terminals and the other two each connecting one terminal and earthing against the motor casing. My 5-4 has a circuit board over the top of the motor with what appear to be the same components [although they are different shapes and much smaller]. The diode is referenced "SS14". I don't have a digital camera but I found some pictures on the interweb [it's a series of tubes]. It looks like the earlier version of the 5-4 did not have the circuit board and the 5-4 motors do indeed connect the terminals with a diode.

Incidentally, the pictures give you a good look at the crappy 5-4 receiver module. The 5-4 receiver is a small circuit board with a 4 sided cardboard cover [open at the axis ends]. [I kid you not]. The circuit board is stuck to the inside of the back of the cardboard cover with double sided tape and the cover is glued shut on top. I have included a crude diagram of the paper engineering.

The front of the cardboard cover is shorter than the back and provides access to the connectors on the circuit board. The problem with the 5-4 receiver module is that the male connectors on the circuit board are undifferentiated pins. The back of the cardboard cover has a legend that states the polarity of the pins [you can just make this out in one of the pictures]. However, there are no JST type connectors to prevent incorrect connection of the motors.

Last night, at about 1 AM, I decided to do myself a favour and level the swash plate. Being the prudent newbie that I am, I disconnected the motors to prevent a rotor slash injury. After 20 minutes of careful work, I connected everything together, placed the coptor in the middle of the floor, stood back a safe distance and advanced the throttle stick to the hover position. A small puff of smoke came out of the receiver module and that was it for my helicopter.

I pulled the cardboard cover off the receiver [noticing for the first time the wiring legend] and observed that two small components adjacent to the motor connectors now have little craters in them. I assume these components [small black rectangles] are the speed controllers. They are referenced "APM4412 [small crater]...AL". I assume that if I could find these components somewhere I could repair my receiver. However, I suspect they are proprietary integrated circuits not available for separate purchase. As it is I decided to buy another 5-4 for $AU129 rather than spend $AU40 for another receiver module. I now have lots of spare parts including a spare transmitter that will become a dedicated FMS joystick.

Incidentally, I notice one of the main gears showed some wear whereas the other looked new. I assume I should reposition the motor connecting to the worn gear so that the pinion is a little closer to the gear. Is this correct? Also, the motors look identical except for the placement of the pinions. The pinions looks like they are stuck to the rotor shafts with some type of glue. I assume it is possible to remove these pinions. If so, how do you do it and how do you stick the pinions back on?

Finally, I now see that the higher quality receiver module on the Walkera 4-1 connects to the motors via JST connectors. So yes, I do want to ask you how you know that connecting the motor backwards will destroy the speed controller. Given the JST connectors the answer is either:

1. You are an electronic wizard with a deep theoretical understanding of all these bits.
2. You decided to do yourself a favour and upgrade the JST connectors and made an understandable mistake.
3. You did something even stupider than me and I can't begin to guess what that was.

And finally [another finally], since you know what a diode is you obviously are more of a wizard than I am. What is a diode and what does it do? Does it have something to do with ensuring the motor only spins in one direction? And what are those little brown lentils? [Are they good to eat?]

Stephen
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Old 09-20-2007, 11:48 AM
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gneu
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Default RE: Blowing up the ESC - Walkera 5-4

Hi,

I had the same problem last week. Eventhough I have good knowledge in electronics, I made the fatal mistake. I connect 1 motor the wrong way around. Smoke came out of the electronic unit.
I found your post by looking where to find the 4412.
Apparently that chips is difficult to find. But I could find a easy to find replacement chip : the IRF7413, which can take up to 13A.
I replaced them today, and after 30 minutes of work, my dragonfly went back up in the air.

The 4412 are burning du to the Schottky diode that is connected across the power leads of the motor if connected the wrong way around. Since that diode has a very low direct drop voltage, it became a short circuit to the 4412. The SS14 is only 1A forward current, and after the burn out off the 4412, was also destroyed.

If you ever think about repairing your electronic part, have a check on the motor diodes too. One of them is surely in short circuit. The SS14 is no cost. In Belgium, it cost 0.29 Euro, but must be buy by 5 pieces. The IRF7413 is 2 Euro each.
I'm sure you can repair yours for less the $5.

I bought mine at RS-Components www.rs-components.com

The tricky part is to remove the bad one from the printed circuit. Personnaly I cut the chips flush to the connections, and then de-sold the connection from the circuit one by one. Then carrefully sold the new ones in place.

Hope this will help.

Best regards
GĂ©rard
Old 09-20-2007, 01:35 PM
  #5  
jtspin
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Default RE: Blowing up the ESC - Walkera 5-4

Oops! Stephen, somehow I missed your post (probably because I don't actually have a 5-4). Hopefully you got it all sorted out by now, but I'll answer your questions anyway:

1. I used to be an electrical engineer, but I gave it up for the glamour of Reno.
2. Nope.
3. Did something equally stupid (OK, it was stupider since I should have known better). I blew up a brand new Blade CP Pro 3-in-1 by plugging my 22E motor into it backwards. [X(][:'(] Nothing like letting the smoke out of something minutes (seconds?) after getting it.

A diode is sort of a one-way valve for current. Connect it one way and no current will flow through it, but connect it the other way and it's practically a short circuit. That's why your 4-in-1 blew up. You basically shorted out the MOSFET (the thing with the 4412 number on it).

The diode is there to shunt the back EMF the motor produces. OK, that probably didn't explain anything. It's there to protect the 4-in-1. Isn't it funny how something there to protect your 4-in-1 can so easily blow it up? (Was that a chuckle I heard?) Want to hear something even funnier? I don't know about the 4-1 4-in-1, but my 22E 4-in-1 already has that diode internal to the 4-in-1, so the one on the motor is redundant.

As for the lentils, they might be good in a soup. But seriously, they're capacitors. I don't have a good analogy for what a capacitor is, but basically it charges up slowly and discharges slowly, so it acts like a filter. It's there to prevent the motor from generating RF interference that could interfere with the receiver in the 4-in-1. If you ever turned on anything with a motor and it interfered with your TV or radio, you saw how RF noisy motors can be.

As for the cardboard on the 4-in-1, I'm not too surprised. Plastic is probably too heavy for the litte 5-4.

As gneu said, these things are repairable if the circuit board isn't too burned up.

Let me know if I can be of any more help.
-JT
Old 09-20-2007, 02:20 PM
  #6  
USHobbySupply
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Default RE: Blowing up the ESC - Walkera 5-4

Oh, man RENO. I used to live there. Its so close to hell that you can see Sparks.
Old 09-20-2007, 09:45 PM
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jtspin
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Default RE: Blowing up the ESC - Walkera 5-4

ROFLOL! Don't know if you're a "That 70's Show" fan, but one of my favorite lines from that show is, "You're still here? I always thought you'd be somewhere more glamorous like Paris... or Reno".

-JT
Old 09-24-2007, 11:37 AM
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Default RE: Blowing up the ESC - Walkera 5-4

Yah, good ole Reno. I used to live in that area. Tahoe (incline), Reno and Carson City. Have a good friend that still lives in Sparks, drive OTR for Fedex.

After i moved out East (Washington DC), the Reno 911 show came on and for a while it was the funiest sh_t on TV.

Anyways, talk to ya later,
Michael
Old 09-25-2007, 12:03 AM
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jtspin
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Default RE: Blowing up the ESC - Walkera 5-4

I came from the Balto/DC area. I'll take Reno over that area any day!

-JT
Old 09-28-2007, 12:03 AM
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Feric Jagger
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Default RE: Blowing up the ESC - Walkera 5-4

JT
Thanks for the answer. What I decided to do was buy a new copter and use the old one for spares. I think the Walkera marketing strategy is that the RTF kits are loss leaders and the parts are what generate the real revenue for the company. It is probably cheaper to buy a spare copter for parts than buy the spares, especially when the spare part is one of the expensive ones (like the receiver unit).

Stephen
Old 09-28-2007, 01:23 AM
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jtspin
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Default RE: Blowing up the ESC - Walkera 5-4

You're not the first one to go that route. I've probably spent enough on spare parts to buy a couple extra RTFs.

-JT
Old 09-28-2007, 10:25 AM
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gneu
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Default RE: Blowing up the ESC - Walkera 5-4

Stephen,

I bought also a second one before I could repair the 1st receiver. Now my spare is ready to fly too.

I don't know the price in your country, in Belgium it is 155 € (euro)
Spare parts in chinaz are cheap even with the shipping cost (if more then 10 item)
See http://stores.ebay.co.uk/WJ-Hobby-an...QQftidZ2QQtZkm

GĂ©rard
Old 09-28-2007, 05:14 PM
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Feric Jagger
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Default RE: Blowing up the ESC - Walkera 5-4


ORIGINAL: gneu


I don't know the price in your country, in Belgium it is 155 € (euro)

GĂ©rard
There is a huge difference in price in Australia. I got my second 5-4 for $AU129 + post which is equivalent to 80 € ([link=http://rchobby.com.au/product_info.php?cPath=43&products_id=356]http://rchobby.com.au/product_info.php?cPath=43&products_id=356[/link])
Old 04-18-2009, 02:10 PM
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Default RE: Blowing up the ESC - Walkera 5-4

I got the same **** happening w<ith my 22e

First the motor burnt the receiver due a crash, now i just received my new receiver 40 euros, and i connect it to be blown up again!!!

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