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Old Jan 21, 2013, 08:16 AM
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I ran a few more tests this morning and we are definitely into the weirdness. These tests were of the voltage at channels 3 and 5, and of the Rx battery itself.



Throttle position had no effect on these tests; nor did the state of the ignition (on or off). However, the voltage started high and just kept going higher - even when the receiver pack was tested directly!

The only thing I can think of is that the meter is defective.
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Old Jan 21, 2013, 08:46 AM
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Are you checking the voltage at the regulator output also during these tests? Its looking to me like the regulator isnt working, or slowing going into a fail mode.
Edwin
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Old Jan 21, 2013, 12:03 PM
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Quote:
Originally Posted by edwin1 View Post
Are you checking the voltage at the regulator output also during these tests? Its looking to me like the regulator isnt working, or slowing going into a fail mode.
Edwin
There is no regulator between the Rx battery and the Rx. Are you referring to the ignition regulator and, if so, how could that be affecting the voltage at the receiver?
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Old Jan 21, 2013, 12:20 PM
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My bad.
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Old Jan 21, 2013, 12:27 PM
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Had to go back and refresh my memory on your layout. What a puzzling problem! Does the ignition switch wire to the receiver have the red wire disconnected? Just pulling straws and throwing out random thoughts. It not, there would be a path for two different voltages to show up at the receiver. I wouldnt think they would be far off enough from each other to be a big deal. You got a head scratcher.
Edwin
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Old Jan 21, 2013, 12:29 PM
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The only thing I can think of is - if the ign regulator failed, and the ign sw wire (+) had a path to the receiver, that would explain how the higher voltages could show up at the receiver.
Edwin

When you fix this, I really want to hear what it was.
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Old Jan 21, 2013, 12:38 PM
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Quote:
Originally Posted by edwin1 View Post
The only thing I can think of is - if the ign regulator failed, and the ign sw wire (+) had a path to the receiver, that would explain how the higher voltages could show up at the receiver.
Edwin

When you fix this, I really want to hear what it was.
I got an interesting piece of information from a member of another forum:

Quote:
If you see voltage rising with a multi meter you're usually seeing a capacitor charge. So your meter is probably just charging a cap in an unloaded circuit. It's not valid data.
If this is the case I may not have a problem at all.
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Old Jan 21, 2013, 01:06 PM
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Thats true, and could be a filter cap someplace. I would at least like to know if your sw voltage wire is isolated.
Edwin
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Old Jan 21, 2013, 01:10 PM
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I would lean toward a defective meter. Is it a digital meter? If so is the battery in the meter good? A low supply voltage in a digital meter WILL give strange readings.

Can you get another meter to compare readings?
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Last edited by Arceenut; Jan 21, 2013 at 01:12 PM. Reason: Added quesrion.
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Old Jan 21, 2013, 01:18 PM
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Quote:
Originally Posted by edwin1 View Post
Thats true, and could be a filter cap someplace. I would at least like to know if your sw voltage wire is isolated.
Edwin
sw voltage wire - meaning switch? Receiver switch or ignition switch? And isolated from what?

Quote:
Originally Posted by Arceenut View Post
I would lean toward a defective meter. Is it a digital meter? If so is the battery in the meter good? A low supply voltage in a digital meter WILL give strange readings.

Can you get another meter to compare readings?
It is a digital meter that I've had for 5+ years and I've never changed the battery so it could well be low or dead. And I think I have another meter somewhere, also digital. If I can find it I'll try it out.
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Old Jan 21, 2013, 01:31 PM
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The ign kill solidstate switch in your second diagram. If there is voltage passed through on the red wire in the connector plugged into the receiver, that might be a path for two battery sources at the receiver. If regulated at close to the same voltage, no big deal. But if the ign regulator failed and passed the unregulated lipo voltage through to the receiver, you would have 7.4v (or whatever the lipo voltage is) also at the receiver. You would read the higher voltage on the meter. Something we call in the business, cascading failure modes. Doesnt happen often, but when it does, it really confuses things.


I'd change the meter battery to be sure. I've been burned by that too.
Edwin
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Old Jan 21, 2013, 01:51 PM
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Originally Posted by edwin1 View Post
The ign kill solidstate switch in your second diagram. If there is voltage passed through on the red wire in the connector plugged into the receiver, that might be a path for two battery sources at the receiver. If regulated at close to the same voltage, no big deal. But if the ign regulator failed and passed the unregulated lipo voltage through to the receiver, you would have 7.4v (or whatever the lipo voltage is) also at the receiver. You would read the higher voltage on the meter. Something we call in the business, cascading failure modes. Doesnt happen often, but when it does, it really confuses things.


I'd change the meter battery to be sure. I've been burned by that too.
Edwin
Hi Edwin... better look at the diagram again - both the rx and ignition batteries are 6.6V LiFEPO4s.
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Old Jan 21, 2013, 03:25 PM
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Oh well, some days its better to stay in bed. I woke up this morning and went to work only to find an empty parking lot. Its a work holiday.
Edwin
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Old Jan 21, 2013, 10:08 PM
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With fresh batteries in the meter I went downstairs to ponder the situation and a light came on. Load... why not plug my throttle servo into channel 3 and advance the transmitter throttle stick all the way to create a load... then plug my test lead and multi meter (with its fresh batteries) into the unused channel 5, and see if there are any voltage changes? Like so:



Heyo! 6.52V, constant for 30 seconds.

At this point I don't see the benefit of further testing. I agree with the conclusion that HS mode on the receiver fried the two throttle servos; I have changed the receiver mode to normal.
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Old Jan 22, 2013, 04:52 PM
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I admit I did not read the whole thread, but I want to mention what popped in to my mind as the problem; fail safe.

Could your failsafe be trying to over travel the servo causing it to bind and burn?

Edit: after reading about Fut HS mode and analogue servos, yeh thats probably what did it.
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