12V power cord funky...unit quits in flight


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May 9, 2023
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I have been using the 740 for years plugged into the cigarette lighter socket with no power issues. After a panel upgrade I hard wired the right angle power plug that came with the unit. Now I have issues with movement of the unit causing it to go blank with no option for backup battery use. It seems that the plug on the new cord is sensitive to movement yet I don't have problems with either the 120v wall wart or the 12V cigarette lighter plug. I checked it with an ohm meter and it doesn't seem to be the plug and wire. Anybody else have any power issues with different plugs? Maybe internal contacts? Maybe bad plug?
If I understand what you wrote (that you're using a cigarette-type "male" plug in a cigarette-type female socket) then it sounds like either the socket has a loose connection, or more likely, the plug is not keeping good contact with the socket. I have seen, at times, in various vehicles, where either the springy pointed end or the side-springs of some plugs don't work well in some sockets. Sounds like the case here -- that the new right-angle plug does not stay snug in your new panel's socket.

You can try spreading the springs on the side of the male plug, or wrap tape around some non-contact part of the plug to make it fatter. Or place some "padding" in the socket to make it skinnier (like thin, double-sided tape). Or find a way to maintain pressure on the plug to keep pressure on the pointy end. Or wire in a different male plug (the old one?), or female socket. If this is the issue here, and if spreading the springs doesn't do it, then that's really what you should do IMHO.
I think he's saying the issues occur when the 740 moves, making it more likely that the problem is in the cord or at the 740 socket connection rather than at the cigarette lighter port or plug.

I don't have any slam-dunk recommendations. Could be in the cord (especially where it connects to the barrel connector that mates to the 740), the barrel connector itself, or the 740 socket. If other cords work consistently well, that tends to exonerate the 740... 🤷‍♂️

If you're able to confirm the problem is with the barrel connector at the 740-end of the cord, then one rather extreme solution, if you don't mind the "ugliness" that will result: Find a spare plug that consistently works well with your 740, and use its barrel connector as a donor.

Cut off the donor connector (keep enough of its cord attached that you won't have trouble splicing it). Cut the balky connector off the hard-wired cord in the panel, then splice the donor connector on, either with crimp splices or with a soldering iron and some heat-shrink tubing. (Make sure you get the polarity correct--you don't want the exposed part of the barrel to be "hot"!!)
Hook...thanks for the suggestions but the cigarette lighter power cord works fine. It's the "new" (came with the unit years ago) hard wired plug that's the problem.

Cobra...I already cut the "new" hard wire right angle plug out of the plane to determine whether the problem is the cord/plug assy. It seems to maintain contact with an ohmmeter no matter how I twist it. That leads me to believe that, since the other two plugs (120 & 12v cigarette) work ok, that it is indeed the male plug itself. Maybe corrosion since its old? I am trying a few other 3.5 x 1.3 mm plugs to see if it solves the problem as you have suggested. Doing the wiring is not an issue since I recently installed two AV-30's and wired the NMEA output to the instruments. My biggest fear was that it was the socket in the 740 that was intermittent...and since they are becoming dinosaurs, I was worried that all my recent wiring would be in vain. I'll keep y'all posted on the results.

Thanks guys!

Since AP no longer deals in hardware, I wonder if one of the forums here could be For Sale. Maybe get some unused 74x units offered up, (and tablets), mounts, power cords, etc. I don't know how much effort it is to start a new forum. This thought occurs to me because of Rob's potential 740 socket problem. Plus, I know you've suggested to other 740 users that they may possibly want to buy a backup unit -- but they're apparently not normally in stock anymore. If AP does come up with an NMEA solution for tablets, then there may be a few suddenly surplus 740 units out there.
I don't know that there'd be enough activity to really warrant a separate sub-forum. If AP has no objections, we could invite folks to offer used iFly devices here in the Portables forum. If the message traffic gets too high, it wouldn't be hard to create a separate sub-forum.

I'm the meantime, any buyers in the market for such items should pay attention to eBay. iFly hardware items routinely pop up there.
Cobra...I already cut the "new" hard wire right angle plug out of the plane to determine whether the problem is the cord/plug assy.
My biggest fear was that it was the socket in the 740 that was intermittent...and since they are becoming dinosaurs, I was worried that all my recent wiring would be in vain.
If you're that savvy, then opening up the 740 and replacing the female power jack is probably within your capability. But you might also call Adventure Pilot first just to see if they can suggest anything else. (They may or may not still be doing some hardware repairs, or might be able to give some guidance in how to open up the device without breaking anything, etc.)
I don't know if A/P can repair it if it is indeed a power socket problem within the 740 unit itself, they have repaired a couple of my units in the past due to similar issues. The last post from the "factory" suggests that they will honor all warranty claims.
The 740 power sockets have always been a weak point especially with the 90 degree one. I use the old and no longer available uAvionix Ping EFB (ADSB-IN) connected to the USB port next to the power socket and the pressure against the 90 degree power connector keeps it connected continuously. Otherwise it is loose and will lose contact.
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I sent the 740 to AP for repair (replacing 12v socket) and the cost was reasonable and the service was quick. They also installed a new battery so now, if I have the same problem, at least the battery will provide temp power and it won't just quit. When I got it back from the shop, there was an issue with GPS reception so it went back to AP again. They fixed the problem and all seems well now and my 12v socket seems secure. Their service was excellent and, as always, friendly.