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I just just bought the 1500mah Life batts from HK. The original battery holder uses center positive and LEFT negative. On the life I just used the center pos and the RIGHT side negative with the small white connector. Any drawbacks to this? Tx works great this way so far.

Also thanks for the awesome firmware and site!

John
Er9x/smartie board/frsky

No issue... Just make sure you always plug it in correctly!


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Yeah I've definitely read the reverse polarity warning threads.

Thanks

Don't do it! But thanks for asking!
It's too easy to plug in shifted over at some other time because it's recessed  and now your battery is connected reversed! Believe it, I've had to repair several 9x's locally already!
Better options,
1. Use the black servo type connector on the life pack it fits but kinda long and the FM pins need to be compressed with a needle some. It can't be plugged in wrong as long as the center is + from HK.
2. Cut the original white  plug off the dry AA battery pack leaving a few inches of wire and splice it to one set of life battery leads. Or make an adapter out of the pigtailed 3 pin white plug. Do not try and swap white connector bodies the pins are not physically the same any will come out. Of course some try and glue them it but again, sloppy.
3. What I've done that's worked so far as a bandaid is to add a little hot glue or epoxy to the side of the life white connector and trim it so it makes a connector that fills up the whole 9x connector. This way you can't plug it in wrong because now it won't mate upside down and right side up it can't shift to the wrong pins to reverse the battery connection.
4. Add a pig tail servo connector to the 9x circuit board using only 2 wires as and then the life battery black connector will only mate one way and again can't be reversed.
Be for warned, if you depend on never making a mistake and don't build in some safety design the next thing you may hear is a loud pop and smell smoke. It sure makes a mess.
That a very common post and wasn't planned but ouch!
Hope I've been of some help to help you prevent a meltdown.
ShowMaster
   

somehing that I don't understand is if it is a 3 pin plug with the + connected at the center, and 2 GND connected on the sides, how can you possibly reverse it even if you connected the other way around??

João

You can't. However some HK transmitter batteries come with a 2-pin, white plug that is easy to plug shifted, and that looks more "suited" than the black servo connector, when it actually isn't.

aahh, that explains it..

While I had mine open one time I just disconnected the wires from the board and hard wired a JST pigtail there. I know you can sometimes get JST connectors to plug in the wrong way round but at least I can see the wires now and check the red is going to red...

Thanks for all the responses.
I'll probably just change the connector on the board when I next open it. My next mod is gonna be the internal spektrum module with a switch to select that or frksy external. I've read the wiki a bunch but im still worried about messing it up.

we all are the first time..

I think I just made the mistake of short-circuiting my 9x. The reason for this mistake was that I didn't plug and unplug that battery that often, and the
right connector on the battery is not matching the one on the transmitter (not matching as in it does not look the same).

I described the whole thing here: https://www.rcgroups.com/forums/showthr ... d-polarity

Then I found out from here that the connectors are: GND, +, GND. This would explain why my LiFe battery heated really quickly and some sparks + smoke were let out. Nevertheless, the transmitter seems to be working. I only tested on a simulator, and it looked like nothing was damaged.

Still, is there any change that something got broken/damaged? I will perform some tests with the receiver as well, just to see if it gets the signals on all channels.

P.S. sorry for resurrecting an old post

Look for something burnt near the battery connector.. But my guess is that the short was just between the 2 outer pins of the connector. That might explain why the radio still works..

João

jhsa wrote: ↑Sun Jul 22, 2018 9:03 am Look for something burnt near the battery connector.. But my guess is that the short was just between the 2 outer pins of the connector. That might explain why the radio still works..

João

Thanks for your answer!

Since the electric current travels the path of least resistance, my guess is also that it traveled between the two GND pins on the transmitter. But then again, I don't really know the internals of the transmitter to be sure. I will first test with the receiver on and then will look inside the transmitter.

Blue

I tested all 4 main channels with the receiver, and it looks like the transmitter behaves ok.
Testing it inside a simulator also works well.

I guess I can assume that I got lucky this time and didn't fry the transmitter.

Thanks!
Blue

I would do a complete check anyway.. If there was smoke, it means something got burnt or half burnt. For sure something got very hot. It could work now but fail later. Look for burnt pins or tracks..

João

The battery connector is on the back board, and the two outside pins both connect directly to the ground plane of the board. This will provide a direct short. If, however, they got hot, you may find the solder melted and/or the small copper traces to the pads burnt. One pad as 3 traces and the other only has 2, so the one with only 2 traces may now be disconnected.
I would not expect anything else to have been damaged.

Mike