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Old May 05, 2009, 07:01 PM
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Crashed... RVOSD gen 2 problem?

Hey guys I was taking my plane up today and had a glich that brought my plane down. While flying I lost all sat signal, then a few sec later lost control and crashed.

Easystar was totaled everything else is fine. But when I looked at the broken plane the reciver had no power on the ground after crash... I run a 12v system and the camera, osd and transmitter was still working in my goggles but the receiver is dead (no red light on my fasst system). So I unplugged then replugged and it lit up and the plane was back to normal... The fact that the power was cut from the osd (osd powers the reciver) during flight makes me believe that it is a osd problem.

Brought the wreakage back home and ran 3 motor tests on the system. Battery 1 drained fine no gliches or sat loss.
Battery 2 drained fine no gliches or sat loss.
Battery 3 test sat connections are fine but then "Failsafe" comes on and the reciver goes dead. Turning my transmitter off then on does nothing. Looking in my plane I noticed the power to the reciver is dead... Cycled the power again and it works fine...

So my guess is bad OSD what you guys think?

Sorry for misspellings it been a long day.


Video: MOV format 39megs: crash.mov
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Old May 05, 2009, 08:18 PM
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Quote:
"Failsafe" comes on and the reciver goes dead. Turning my transmitter off then on does nothing. Looking in my plane I noticed the power to the reciver is dead... Cycled the power again and it works fine...
Do you mean the RVOSD is going into "failsafe" or does you receiver have a failsafe mode?

It seems really odd your receiver power would go dead. How many servos do you have and do you have a separate BEC? RVOSD doest supply power to the servos, it only fees it through.
I'm thinking possibly when RVOSD goes into failsafe it simultaneously moves all sevos to the "failsafe" setting. This would put a Maximum current draw on your receiver, possibly causing it to shut down.

If you don't have a separate BEC I would say get one. I hear the ones built in to ESCs are not enough to safely run more than 4 servos.

If you have the 50A RVOSD current sensor read this:
http://www.rangevideo.com/forum/showthread.php?t=178
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Old May 05, 2009, 09:42 PM
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Originally Posted by Martin V
Do you mean the RVOSD is going into "failsafe" or does you receiver have a failsafe mode?
Hey thanks for the reply, osd blinked "failsafe" for .4 of a sec didn't even know it untill I watched the recording. Servos are the 4 mini's - 2 from the orginal easystar and 2 from RV servo tilt/pan kit. Funny thing is I have about 10 flights with this without issue. Just got the OSD 2 weeks ago.
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Old May 05, 2009, 10:04 PM
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Martin,

What does a BEC do? I read somewhere what it stood for, but I don't know exactly what one is used for. Is it something in which I should consider investing?

-TL
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Old May 05, 2009, 10:14 PM
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Originally Posted by wtl0715
Martin,

What does a BEC do? I read somewhere what it stood for, but I don't know exactly what one is used for. Is it something in which I should consider investing?

-TL

Battery Ellimination Circuit, they come built in with a ESC. The BEC also has logic which senses the battery voltage, and at the low end of voltage, the BEC will shut down power to the propeller assuring the rx and servos with the last bits of electric power, and thus a safe landing.
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Old May 05, 2009, 10:20 PM
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So the RVOSD was designed to give the receiver its power?????

Nope, don't believe I would have used that feature. Just too much at stake to trust an OSD to power the receiver, do we even know what kind of receiver load the RVOSD can handle? A simple bec like from CC that I know can handle 3 amps continous with 10 amp surges is just too easy to implement to have to risk a crash over.

A bec means battery eliminator circuit. It refers to anything other than the standard 4 or 5 cell battery that gives a receiver its power.
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Old May 05, 2009, 10:30 PM
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RVOSD does not supply power to the receiver, all servo inputs and outputs have the Vcc pin connected together but internally isolated from the OSD, so your Receiver gets his power from the BEC on your ESC probably. Check the servo cabling and connectors.
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Old May 05, 2009, 10:42 PM
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Quote:
Originally Posted by Elcheapo
RVOSD does not supply power to the receiver, all servo inputs and outputs have the Vcc pin connected together, so your Receiver gets his power from the BEC on your ESC probably. Check the servo cabling and connectors.
Ahhh, that explains it then. He was using the bec in his esc and it either overloaded or overheated and shutdown. And after the crash it had a chance to cool and to reset itself when he cycled the power. Makes more sense now. That would also explain why it now appears to be working just fine.

It's not the bec in the esc that stops the motor when the pack hits LVC, it's the esc itself. The bec is usually an independent circuit within the esc which is why it can continue to function after the esc has shut the motor down, but they are only made to handle three maybe four servos. If you overload it with two extra servos (pan/tilt), and/or try to power an osd with it, then it's no wonder it quit on you.

Don't fly this setup again until you get an external bec such as the CC bec (castle creations).
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Old May 05, 2009, 10:46 PM
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Quote:
Originally Posted by Carlyle Harper
... If you overload it with two extra servos (pan/tilt), and/or try to power an osd with it, then it's no wonder it quit on you. (castle creations).
The OSD does not get his power from the BEC, It has an internal switching regulator that takes the battery voltage 6-30V and convert it to the voltages used inside the OSD. So it will not charge a single miliampere to your BEC.
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Old May 05, 2009, 10:56 PM
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Ok, so it's not the osd's fault here like he tried blame it on. He even said osd, transmitter, camera were still working in the goggles.

Still, no power to the receiver means a bec problem. Actively flying and using pan/tilt could have overheated it especially if he had it stuffed inside all that styrofoam a very good insulator, not to mention heat from the esc running the motor.
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Old May 06, 2009, 12:03 AM
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Quote:
Originally Posted by Elcheapo
RVOSD does not supply power to the receiver, all servo inputs and outputs have the Vcc pin connected together but internally isolated from the OSD, so your Receiver gets his power from the BEC on your ESC probably. Check the servo cabling and connectors.

Nope ESC is connected to 3 things motor, RVOSD current sensor (power), and the output throttle pins on the RVOSD.
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Old May 06, 2009, 12:10 AM
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Quote:
Originally Posted by Carlyle Harper
Ok, so it's not the osd's fault here like he tried blame it on. He even said osd, transmitter, camera were still working in the goggles.

Still, no power to the receiver means a bec problem. Actively flying and using pan/tilt could have overheated it especially if he had it stuffed inside all that styrofoam a very good insulator, not to mention heat from the esc running the motor.

ESC (and BEC) connect to the RVOSD, for autopilot and failsafe output. Still pointing at OSD. I will be running a pwr regulator from the rvsensor to my reciver power for a backup from now on.
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Old May 06, 2009, 12:17 AM
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Quote:
Originally Posted by petry79
ESC (and BEC) connect to the RVOSD, for autopilot and failsafe output. Still pointing at OSD. I will be running a pwr regulator from the rvsensor to my reciver power for a backup from now on.
Ok let me clear the things further. Internally on the OSD there is a direct copper trace between the Vcc pin of throttle in (ESC-BEC) to the rest of inputs (Rx) and outputs (servos), and this copper trace has no internal conection to the rest of the OSD. I hope you can understand whats the meaning of this.
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Old May 06, 2009, 12:20 AM
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Originally Posted by Elcheapo
Ok let me clear the things further. Internally on the OSD there is a direct copper trace between the Vcc pin of throttle in (ESC-BEC) to the rest of inputs (Rx) and outputs (servos). Actually not a single copper trace but one on each side of the PCB. and this copper trace has no internal conection to the rest of the OSD. I hope you can understand whats the meaning of this.
Thanks but I trust ya. Running a backup power of main batt from now on. Here is the video:

MOV format 39megs: crash.mov
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Old May 06, 2009, 12:22 AM
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No, I think you're misinterpreting the symptoms.
The OSD is showing you the problem, it's not the cause of it.
The "Failsafe" indicator is actually the key. There's a servo channel to
control whether the OSD is in failsafe mode.

What's happening is your ESC's BEC is shutting down (as suggested above)
and that cuts the power to the receiver (which is passed through hard
wires from BEC to OSD to Rx). The OSD sees the signal
go away on its control channel and goes to failsafe mode, at least
momentarily.

Run the test again and when it shuts down, check the voltage at the
BEC's output (before the OSD and before the receiver). It'll be dead.
You might be able to hasten the failure if you move
all the servos a bunch while the motor is running.

ian
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