General YEP ESC fries receiver - help?

KenL

New Member
I recently acquired a used Thunder Tiger 450 size heli that came with servos, motor and ESC, but no receiver. I wanted to set it up with a Spektrum compatible receiver, as my main transmitter is a DX9. I got a new Lemon DSMX 6 channel receiver - I have used these in planes and helis before, always with success. The YEP 45 amp ESC that came with this heli is unusual (to me) in that it has two sets of wires coming from it, both of which appear to be receiver connections. Both sets have all three wires connected. The only apparent difference between them is that one set appears to be using heavier gauge wiring than the other. It appeared that the previous owner of the heli had been using the heavier gauge 'receiver connection' as this was run to the back of the heli, where the receiver had evidently been before, whereas the lighter 'receiver connection' had a piece of tape over its end. So... I connected the heavier 'receiver connection' to the throttle connection of my receiver, put a bind plug into the receiver, and connected one of the cyclic servos, then I plugged in a battery (3s LIPO, 2200mah) expecting to be able to bind the receiver. But the receiver immediately fried in a cloud of sparks and smoke. Can anyone advise me as to what is happening here? I can only assume that too much voltage was put into the receiver. I'm sure all the wires were connected the normally correct way, with the signal wire (yellow, orange or white) on top and the ground wire (brown or black) on the bottom. I cannot find any documentation explaining why there would be two sets of connection wires on a YEP ESC. And all the documentation I have says that the BEC for the YEP ESCs is fixed at 5.5 volts. So why did this one fry my receiver? I have other YEP ESCs also, and they only have one receiver connection wire. At the moment, I don't know what to do... other than just pitch this YEP ESC and start out with a new ESC and receiver. :dejection:
 

Smoggie

Well-Known Member
The other wire is for programming the ESC, so you did the correct thing in connecting the longer/heavier wire. The programming wire just sits disconnected when you arent programming.

Connecting the plug the wrong way wouldn't have fried the receiver unless someone has swapped over the pins in the plug so that the red wire is no longer in the middle? Only other things i can think of is a faulty receiver or a faulty BEC in the ESC that is passing full battery voltage through.

Before connecting anything else to the ESC you should check the voltage across the red and brown wires to see that it's not too high. If it checks out ok then most likely it was just a bad receiver.
 

KenL

New Member
Thanks, Smoggie. The whole thing makes me very nervous. As you say, checking what is coming out on that wire before plugging it into anything else sounds like a good idea - I guess I'm going to have to get a multi-meter. I've had one in the past, but I don't think I could lay hands on it now, so I guess I'm going to have to get a new one.
I'm thinking, also, that the fact that I was trying to bind may have contributed to the issue - although bind plugs just connect the signal to the ground in the bind socket, so maybe that's not relevant.
I've used those Lemon receivers before, but never with such a high amperage ESC. Still the BEC voltage is only supposed to be 5.5v, which ought to be ok. Some people have said they were getting 5.7v on the BEC from YEP ESC... I wonder if that would be high enough to fry the Lemon receiver...?
 

Smoggie

Well-Known Member
The lemon receivers work normally with a direct 2s LiPo for high voltage servo setups, so thats 8.4V at least.
 

KenL

New Member
Well that's very interesting to hear. It's looking more and more as if this was just a defective receiver. Actually I see on the Lemon Rx site, it says "Voltage range: 3.45 - 10.2 V" for the particular receiver that I was using. I'm still going to check the voltage... but I think that must have just been a bad receiver. I bought two in the same order - I guess, if the ESC/BEC voltage checks out ok, I'll try the other Lemon from the same order... and fervently hope it doesn't turn out to be a lemon, if you'll pardon the pun.
Thanks again for your prompt and informative help.
 

KenL

New Member
So... the rest of the story.

I went out and bought a new multimeter today, since I couldn't find my old one - cheap, 14 bucks at Canadian Tire for a 4 function digital one. I hooked up the ESC to a battery, with the motor disconnected, nothing else, and went to check the voltage. I got a very brief reading that looked like 12 or so, then the ESC itself went poof and emitted smoke and died.

So... I had another YEP ESC on hand, that I had bought for another project (and the programming card to go with it). So I programmed that, installed it, hooked up the other new Lemon receiver that I had, and bound it. All OK. So then I plugged in all of the servos, checked them. Then the gyro. Then the motor. So now I have everything working OK with the new ESC and receiver. Of course, I haven't actually tried to fly the heli yet. But everything is working, and moving in the right direction as per my Spektrum DS9. So definitely looking better than yesterday. Of course, I have to order another receiver and ESC now... but c'est la vie.

Still don't really know whether the problem initially came from the ESC or receiver... but since they're both toast now, that's a moot point.
 

Smoggie

Well-Known Member
Most likely it was the BEC in the ESC that failed and passed full battery voltage (12.6V for a fully charged 3s LiPo) to the receiver.
 
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