Two dodgy FrSky XM+ receivers in a row - the hunt for answers

English Turbines · January 31, 2018, 04:13:39 PM

Jeez, that awful....No range at all....signal dropped like a stone....:(

:vulture:

CurryKitten · January 31, 2018, 04:23:42 PM

Quote from: Loopdreams on January 31, 2018, 04:07:10 PM
It might be worth swapping the antennas between the good one and the duff one. Also are you changing the TX mode before binding after swapping between 16 and 8ch firmwares?

I would swap the antennas, but given there's two duff ones and the antennas look good, it seems unlikely. On the 8 channel thing, that is a bit of a weird one. I noted that betaflight did not like it when I ran 8 channels at 9ms frame size. It let me run it at 18ms (the norm for 16 channels - even though I was in 8 ch mode) but the "good" rx also had issue here.

Loopdreams · January 31, 2018, 04:30:41 PM

That seems strange, I'm using the 9ms on Betaflight and it's fine but there's just so many variables with these things.

CurryKitten · February 02, 2018, 10:15:10 AM

FrSky replied this morning, and after explaining what happened again, and them taking a look at the video they are interested to take a look at the receivers. They asked to see a "two dimensional code" which I guess is something written on them, so I took this picture.

I'm not sure if it's what they want, but would be interested to know if you guys have good receivers with the same writing on them.

Coyote · February 02, 2018, 10:19:56 AM

That's interesting, see what comes of it.

FPVSteve · February 02, 2018, 02:39:32 PM

Are the little antennas soldered on or do they use those little tiny SMA connectors? I had a problem with a D8RII+ which had next to no range and the antennas were actually disconnected from the board once I opened the receiver up.

Nowadays I open them all up and hotglue them before use.

Although writing this I notice there's not actually a box to hide the antenna connections on these micro rx's so I imagine you'd notice if the antennas weren't connected.,

Weird one.

CurryKitten · February 02, 2018, 03:22:54 PM

Yes - they can pop off Steve, so it's worth looking at them. They come out of the factory with a bit of adhesive over them, but they can wiggle loose - I've had it happen in the past. In the case of these two though, they are all fine.

SimJen · March 17, 2018, 09:00:00 AM

Hey Curry Kitten,
I've got two of these with the same numbers and both give dodgy results.
They will bind okay, but will fall out of the sky. Also sometimes even at close range they will lose connection before reconnecting.
Sounds like frsky have had a bad batch!
I'll be sending mine back for warranty replacement shortly.
Annoying as i just upgraded to a qx7s tx and these xm+

CurryKitten · March 17, 2018, 10:38:08 AM

I may have an update on this. I had an action left to try winding back the firmware level to an earlier version. I tried this on one of the receivers and it seemed to work. I had good levels of RSSI within the house, and took it out to fly and it performed as expected.

To check if that's it - I'm going to freshly flash the latest version onto the other dodgy rx, range test as before, and then go back to a previous version and do the same. I need to check this is reproducible before saying "fix it like this"

English Turbines · March 17, 2018, 09:51:20 PM

Quote from: CurryKitten on March 17, 2018, 10:38:08 AM
I may have an update on this. I had an action left to try winding back the firmware level to an earlier version. I tried this on one of the receivers and it seemed to work. I had good levels of RSSI within the house, and took it out to fly and it performed as expected.

To check if that's it - I'm going to freshly flash the latest version onto the other dodgy rx, range test as before, and then go back to a previous version and do the same. I need to check this is reproducible before saying "fix it like this"

Hi Wayne, for the benefit of others reading this, I assume you are using the LBT version of Firmware, because I know the latest version of the International Firmware for the XM Plus receiver works ok...
It sounds like a dodgy (LBT) Firmware release rather than a physical component fault, which is good news methinks..?

:vulture:

SimJen · March 17, 2018, 11:15:17 PM

Quote from: CurryKitten on March 17, 2018, 10:38:08 AM
I may have an update on this. I had an action left to try winding back the firmware level to an earlier version. I tried this on one of the receivers and it seemed to work. I had good levels of RSSI within the house, and took it out to fly and it performed as expected.

To check if that's it - I'm going to freshly flash the latest version onto the other dodgy rx, range test as before, and then go back to a previous version and do the same. I need to check this is reproducible before saying "fix it like this"

I've just tried this and it still loses signal at close range. I can fly around a little bit, but the moment i bring it close, signal is lost and quad crashes. I can replicate it on the bench also. Nothing loose, lbt and fcc firmwares.
I also have an xjt module and I've tested them with that and exactly the same results.
I just can't trust them now, makes me wonder why i bothered upgrading. Just finished my armattan rooster too, but won't try maidening before this is sorted.
Have another xm+ coming next week, so will test that one. Hopefully will give better results.

CurryKitten · March 17, 2018, 11:51:53 PM

Nope, I'm using the international version, or FCC as they call it these days. I've certainly got multiple XM+'s on the latest version with no issues, but one of these dodgy ones that fell out of the sky at less than 100m range, and dropped to under 50% if I walked downstairs now has 95%+ walking downstairs, and I used it to test a DroneKeeper Micro yesterday by putting it down in the bushes about 200m away, and it had 90% going in (and then I lost video as I was blocked by bushes)

It doesn't mean that my other XM+ will magically come to life, but the symptoms do seem similar, and clearly a different situation than SimJen. But it's entirely possible that little differences in the manufacture, or slightly different components could result in a firmware issue arising that wasn't seen in the previous testing, and that was present in the previous firmware.

If I can replicate with my other receiver, I'll make a video and send it off to FrSky to see if they have anything useful to say.

Quote from: English Turbines on March 17, 2018, 09:51:20 PM
Hi Wayne, for the benefit of others reading this, I assume you are using the LBT version of Firmware, because I know the latest version of the International Firmware for the XM Plus receiver works ok...
It sounds like a dodgy (LBT) Firmware release rather than a physical component fault, which is good news methinks..?

:vulture:

English Turbines · March 18, 2018, 01:02:01 AM

Oh, bugger...that's bad news then huh..?

The one thing I have noticed, and I have two XM Plus RXs now, is a little swamping really close in. The RSSI stabilises and improves as the model flies away from me. Other than this, no issues at all. Six Km range has been proven with this receiver.

I guess they will just replace them for you, you being famous and all.....:)

:vulture:

SimJen · March 21, 2018, 01:58:06 AM

My new xm+ has arrived and works considerably better than the other two! Interestingly the original 2 had the words "no test" on the packet. The good one doesn't.... Does this mean it was tested at the factory?

BigT · May 15, 2018, 09:55:39 AM

So picking up on this theme of range and rssi with Taranis. I am wondering if I have a bad backboard on my X9 Plus. With the latest iNav you can put the RSSI onto a channel and get the rssi on the OSD. I have suspected a poor range issue with this tx for some time. I have carried out the range check procedure and it seems ok and I have the rssi warnings set as standard in the tx. I never get 100% rssi, even with the tx and Rx 2 meters apart. I get the normal telemetry loss close in. However in flight I get rssi warnings flying LOS at around 100 meters distance and 150 meters alt, and this is with all types of rx and now I cannot bring myself to fly at any range even though I have never had an actual failsafe with iNav. I have had 2 models flown LOS spin in, totally unexplained, with different rx. My Futaba kit is good for 3k LOS so I was expecting the same from the Taranis.

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