I have not tried the FMA, but I use this one:

http://www.vexacontrol.com/servoxciteref.html

Excellent unit, Mike Weidner found it.

As for a current meter I prefer an analog type, the old one I have from Custom Electronics is so sensitive I can detect missing gear teeth when I sweep the servo. They still make an analog unit, looks like they have added features to it.

http://www.horizonhobby.com/Products...ProdID=CEL1430

You can also check what that channel is putting out, pulse-width-wise, without buying the Hitec programmer or anything else, using one of your ECU's like a FADEC or Jetcat, which give a value to pulsewidth when in the "stick-teaching" mode.

Woketman wrote:<<All that would do is melt wires, NOT the servo case or motor>>.

My company services electronic dispensing and pos computer systems, i can assure you that ANYTHING can happen when you get a spike, surge, short etc...JH, you probably should swap out the ecu and try to find out what is NOT causing the problem which will lead you to what IS the problem.
V..

When I get home tonight I will zero out all the throws programmed on CH 5 with a new 8411 ( haven't done it with such high quality servo for the record ) I also ordered today from Todd a servo voltage meter to check the actual voltage from that channel like you guys are suggesting.

I run 6V dual packs on separate channels ( two switches ) without a regulator ( never used them, don't like them ) on all my Jets and this has never been an issue, also keep in mind that this is NOT a new Jet, this jet was built for me and it has been flying all year since October of 05, this started happening now.

Vincent the servo is very close to the RX therefore there is NOT an extension running to the RX.

I will post pictures of the reading from all the channels along with the results from the 8411 with absolutely no throws, without the servo arm and maybe we can all get to the bottom of this cause I sure don't have a clue !! I will run this test with only 1 battery pack connected to the RX.

Thank you so much for all your suggestions.

No question.

My guess might be an intermittent with the signal trace on the Rx bus, perhaps an intermittent short to the power bus, something making the pulse width vary and causing the servo to drive hard over. That or the TX program or hardware has gone nuts and is causing the servo to overdrive, that is the only thing I have ever seen melt a servo case, driving hard againt the stops.

forgot to ask,

Should I still run these tests with the same RX that's in it or drop a new one in there?

If you change out the RX and it still happens it is likely in the Tx settings or TX hardware (VERY unlikely the hardware in my experience)

My guess is it will go away when you swap out the RX. If you want to know what it was for sure, you will need to run that analyzer on the old Rx.

A fresh charged 5 cell pack is putting out close to seven volts, maybe the 368 is unhappy running at that voltage.
Could it be that in other installations where this same servo was running through an exstention and there was enough of a voltage drop to keep from frying the the servo in question?

Johnny, another thing to do: assign channel five to a stick (such as aileron) so that you can vary the movement (besides just one end to another like a retract switch). Then you can see that the servo is not driving hard against the stops. Take note of the servo arm position when centered, all one way, and then all the other way. Then go back to your current configuration. Is it now very far from where it was when it was assigned to the aileron stick at center? One end? The other end?

I have one of those FMA Servo Labs that Rob was talking about. It really is a great tool.

Johnny, what did you find out?

After following instructions from all of you, I discovered that my RX was sending higher Voltage to CH 5 and the Amp was out of whack. I'm sending the RX along with all the servos to Horizon ( John R ) so they can study the issue and figure it out . I dropped a new RX in the Jet and problem solved, I flew the Mig today and everything was A-OK. Now I have to remember to air up my gear


Thank you all for your help, this was an interesting one..

J, please let us know what they say when you find out. Thanks.

Does the servo fail shortly after turning on the switch? If so the servo may be getting reverse voltage polarity from a missed wired extension cable.

If it works for awhile then fails I would look for over travel and high current from working against the mechanical stops in the servo.

Hi JH,
Weird problem for sure, keep us informed on it. Also do you have any visual problems with seeing your all black mig in the air?? Cool looking paint scheme. V..

Yes, it works for 3 minutes and it fries shortly thereafter.

Vinny,

Everyone tells me how great they can see that thing but I have to be honest with you, I'm constantly rocking the wings back and forth to make sure she's going the right direction . Its a great scheme but when far away you have to pay close attention to it

JH,
Thanks, i figured that would be the case. Rocking the wings especially on the down wind is a good idea for sure. I do the same with my all silver CARF Mig. V..

I didn't think that the servo voltage was tied to an amp---The voltage that the servo receives is equal to the RX pack---It's all on one bus---That's how you can run dual RX packs, switched failsafe packs, etc............The voltage to one servo should be equal across the entire servo bus.....Do you mean that the signal line to that one servo was over-producing??? We're all curious about this so please let us know what JR service discovers...[sm=thumbup.gif]

Kevin