Electronics issue with my Raptor 50 - RC Groups
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Apr 23, 2012, 02:15 PM
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Electronics issue with my Raptor 50

I decided to try to fly my Raptor 50 again after about 2 years (built it 8 years ago) except there's something wrong with the electronics. It worked perfectly the last time I flew so I'm having difficulty understanding why the electronics no longer work.

The power source is a 3-cell LiPo pack that charges normally (the charger would have reported a battery problem if that was the issue). The power runs through an Ultimate BEC and then to the receiver (Hitec FM HPD-07RH) which lights up green when I hit the power switch. My Futaba gyro (GY401) starts blinking so it has power, and the lights on my governor (Throttle Jockey PRO) come on, however my digital servos (Futaba S9252) don't move as if they are unpowered.

I didn't do anything to it since I last flew it and no combination of unplugging various servos gets any of them to move (yes my Tx is switched on). Again it's been a while so I've forgotten a lot about how I originally built it and set it up, but I'm not sure how to troubleshoot the issue with the servos.

Please give me some suggestions of what the issue may be or some troubleshooting options. I don't want to start replacing parts at random and I'm not as into flying as I used to so if I can't get it working cheaply I may just sell everything off.

Please help. Thanks.
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Apr 29, 2012, 04:30 PM
Fly, Crash, Repair & Repeat
From what you describe it sounds like the reciever has came unbound to the transmitter. Does your transmitter let you bind to a reciever ( like the 2.4 GHz stuff) or are you using crystals? If you are using crystals check if your crystal came loose. If you are using the other stuff try rebinding the reciever to the transmitter.
It sounds like the reciever is not getting a signal from the transmitter.

good luck
Apr 30, 2012, 07:09 PM
Registered User
thanks for the input. I am still using the ancient 72 MHz tech and the crystal is seated properly. I remember in the past even if I turned the heli on prior to the transmitter the servos would still start buzzing. Right now whether the transmitter is on or not the servos are silent. My battery is putting about 12 V to the UBEC which is converting it to 5V to the receiver.

Do receivers just randomly die?

That seems to be the only thing I can think of at this point. Somehow time passing wore out an internal component of the receiver.
May 05, 2012, 12:46 AM
Registered User
Tried a new receiver, still no servo response, and still no clue what the problem could be.
May 05, 2012, 04:28 AM
Registered User
If you have a hobby shop or RC club nearby, they might be nice enough to use a servo tester/cycler to see if the servo's are bad.
Normally I would plug one servo in at a time, for a test. sounds like you might have already tried that.
May 05, 2012, 05:38 PM
Registered User
Yeah, I've tried plugging in servos individually. Though if it's not the battery, UBEC, Rx, then maybe it is that all the servos are dead. I know power is getting to them cause my gyro and governor show indicator lights, and I checked the UBEC is putting out the proper 5V to the Rx. Still stumped though and not sure it's worth trying to replace all my servos.
May 06, 2012, 06:51 PM
Registered User
This morning, nothing was working still, but since it was a nice day decided to pack it up and head to the flying field to see if someone there would help me troubleshoot. Once the helicopter was all set up, I hit the power switch and to my surprise every servo began chattering with life. I didn't change a damn thing between my home and the field. Even got the motor fired up with a glow plug replacement, though I'm going to have to tweak the throttle servo position to get it up to idle.

Still not sure what the problem is, but now I suspect there's some sort of frequency interference going on at my home. Very strange indeed.

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