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Aug 12, 2019, 01:31 PM
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Weird Rx Socket Problem


I have scratch built with a NEW Spektrum EFLU5864 Rx (used in the Cessna 182). Before I call Horizon maybe someone can help.

On the maiden, the wing came off just after takeoff (not enough magnets) and pulled both servo wires from their sockets. No obvious damage to the sockets or pins.

Now on power up, the servo on one of the aileron sockets slams to full up and cannot be controlled by the TX. Tested servo on the other socket and it works fine. Tested the offending socket with a new servo and same problem (servos do not appear to be damaged by the test).

Any one have any ideas? Thanks for any help.
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Aug 12, 2019, 03:10 PM
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AntiArf's Avatar
If I'm reading this correctly, it's possible that a pcb solder joint on the opposite side of the socket (see photo) https://www.rcgroups.com/forums/show...99&postcount=3 was damaged when the connector was yanked out of the socket. Seems it could be the signal pin that the orange wire plugs into, as the servo does power up in order to travel to one end. Could make sense, as the signal pin is at one end of the connector, and an end pin would be the most stressed in the event of a connector being yanked out abruptly. If it's the case, the pin to pcb solder joint could be heated with a fine tip iron to reflow the joint. You should be able to see a cracked solder joint with a magnifying glass, if that's what happened.
Aug 12, 2019, 07:08 PM
If it flies, I can crash it.
rocketsled666's Avatar
I agree with your diagnosis, AntiArf. But I think the sockets on that RX are surface-mount, not through-hole. Which is probably why the signal pin connection is now busted. Surface mount connectors are a lot easier to pull off the board than through-hole. If the OP has a reflow heat gun, it might be repairable. But the spacing is tight, so my expectation would be low if it was my RX and I was trying to repair it (and I do have the tools).

What I would do is cut away the plastic shroud until it's completely removed. That'll expose the pins (any that are still attached) and two little "anchors" that are supposed to help hold the connector to the PCBA. Then I would remove the remaining pins and the anchors with a pencil soldering iron. Then I would get a servo lead extension for this kind of connector and I'd cut it in half and solder the male end to the exposed pads on the PCBA. Then I would plug the servo in to that extension...

Usually, though, when these connectors come off the board they take the pad with them, and there's only a very small trace that remains that is nearly impossible to solder to. So this may not be repairable at all.
Aug 12, 2019, 08:16 PM
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Here is what I have observed in the sketch in the attached PDF file. On the outside, things look solid and connected.
Aug 12, 2019, 08:49 PM
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Quote:
Originally Posted by rocketsled666
I agree with your diagnosis, AntiArf. But I think the sockets on that RX are surface-mount, not through-hole. Which is probably why the signal pin connection is now busted. Surface mount connectors are a lot easier to pull off the board than through-hole. If the OP has a reflow heat gun, it might be repairable. But the spacing is tight, so my expectation would be low if it was my RX and I was trying to repair it (and I do have the tools).

What I would do is cut away the plastic shroud until it's completely removed. That'll expose the pins (any that are still attached) and two little "anchors" that are supposed to help hold the connector to the PCBA. Then I would remove the remaining pins and the anchors with a pencil soldering iron. Then I would get a servo lead extension for this kind of connector and I'd cut it in half and solder the male end to the exposed pads on the PCBA. Then I would plug the servo in to that extension...

Usually, though, when these connectors come off the board they take the pad with them, and there's only a very small trace that remains that is nearly impossible to solder to. So this may not be repairable at all.
Good points. It looks like the pads can be seen next to the connector, in the photo linked that I posted previously. He could always try a continuity test between the pad next to the connector, and the pin. Might be able to just solder the stripped and twisted wire ends of a servo extension lead with a socket onto the pads next to the connector, as you were suggesting.

Just read his file that said he continuity tested, so this is strange. If the servo works in another socket then it's not the servo that's the problem, while they are known for H-bridge failures that cause them to slam to one end. Could have a slightly bent pin or one not making contact for whatever reason. They're fiddly and I've ran into that with 1.0 connectors, which is why I prefer the larger 1.5mm JST. Wish they had gone with those.
Last edited by AntiArf; Aug 12, 2019 at 08:56 PM.
Aug 13, 2019, 10:51 AM
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glewis's Avatar
Could be the pads are lifted just enough to have broken the signal trace? Pins will still be soldered to the pads, but pads ripped off substrate. Should be easy to spot looking from the edge of the board.
Aug 13, 2019, 12:30 PM
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Tried to call Horizon for help, but couldn't wait on hold and had errands. But here is something interesting: I ordered the current Cessna 182 Rx (EFLU 5864) from Amain Hobbies. But I just now noticed that what I got (from the label on the back) is Rx EFLU5650V1, the OLD ORIGINAL Rx that came on the Cessna. I wonder if E-flite retired the 5650 Rx because of problems like I'm having.
Aug 13, 2019, 04:42 PM
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Quote:
Originally Posted by alset
Tried to call Horizon for help, but couldn't wait on hold and had errands. But here is something interesting: I ordered the current Cessna 182 Rx (EFLU 5864) from Amain Hobbies. But I just now noticed that what I got (from the label on the back) is Rx EFLU5650V1, the OLD ORIGINAL Rx that came on the Cessna. I wonder if E-flite retired the 5650 Rx because of problems like I'm having.
My mistake! The EFLU5650 is the entire Cessna 182 - not an Rx designation even though that code is on the Rx.
Aug 13, 2019, 05:48 PM
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Quote:
Originally Posted by alset
Tried to call Horizon for help, but couldn't wait on hold and had errands. But here is something interesting: I ordered the current Cessna 182 Rx (EFLU 5864) from Amain Hobbies. But I just now noticed that what I got (from the label on the back) is Rx EFLU5650V1, the OLD ORIGINAL Rx that came on the Cessna. I wonder if E-flite retired the 5650 Rx because of problems like I'm having.
If you have continuity between the pads next to the connector and the pins, then maybe it's possible that the servo unplugging caused a software glitch. People have had mixed results trying to reprogram these units.
Aug 14, 2019, 09:36 AM
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To all who replied to the original post: Thank you. But the problem was sort of resolved by calling Horizon Technical Support. After explaining the problem, they simply just said they would send me a new Rx ( of the couple of these Rx's I have, one had been ordered from Horizon).

So presumably they will figure out why the broken one quit working properly. And it appears that ordering from Horizon has its advantages.


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