X06 servos go crazy with GR6

[Wayne]

We have been after FrSky to use a little more solder on these pins, just seems like good practice, but they have an argument for doing it there way, just have no idea what that argument is. They have done that for a very long time.

 

[Landru]

I recall now a report a few years ago of problems with the soldering of the pins on some G-RX8.

I'll report back on resoldering this GR6. Not sure if I can get to it today. I may need to set it aside until tomorrow.

 

[Konrad]

We have been after FrSky to use a little more solder on these pins, just seems like good practice, but they have an argument for doing it their way, just have no idea what that argument is. They have done that for a very long time.

Could it be that wave flow lead is expensive?

 

[Wayne]

Not sure if they wave flow the connectors..? I recall reading a someone stating a reason for the pins to be soldered the way they are, but the heck if I recall what it was..

 

[Nigel]

I used X-06s and a G-RX6 in my DLG - no issues with either.

 

[Landru]

Thanks for the continued interest and comments. I can give an update now.

First, before reflowing the solder joints on the output pins, with my DMM, I checked for discontinuities between the various pins and various points on the PCB. I didn't find any. Then, I reflowed the solder and checked again. Not surprisingly, I didn't find any.

On to the big test: Did reflowing make any difference in the behaviour of the receiver with X06? In a word, no. The extreme jittering remained as before.

Some further testing with various power sources (including a variable DC power supply) revealed the following:

1. With supply voltage greater than about 5V, the X06 behaved as expected.
2. With supply voltage about 5.0-4.7V, the X06 went crazy.
3. With supply voltage at 4.6V or lower, the X06 didn't respond to control input from the transmitter.
4. When the receiver was power cycled by unplugging the supply from the input pins, occasionally it would not boot.
5. When a servo was unplugged and plugged back in to the receiver, occasionally it was totally non-responsive.

The first three points above are captured in the video below. About one minute into the video, I power cycled the receiver to try to reproduce the power up problem. However, it powered up normally.

To my mind, the last two points above (4, 5) suggest an intermittent contact problem that I didn't catch with my DMM testing. Or I suppose there may be an intermittent failure in a component on power up. Regardless, the first three points -- and the fact that the receiver and leads were not moved during the test -- suggest another voltage-related problem. Bottom line: there's something wrong with this GR6 that I likely won't be able to fix.

 

[Konrad]

Sorry, to learn this is still an open issue.

 

[Landru]

Me too.

Perhaps some bright spark understands the significance of the voltage findings. It seems to me they indicate a problem distinct from any intermittent connection. In any case, my attempts to repair don't extend to replacing SMD components at this size.

If there's no other option, I might consider removing and reinstalling all the PMW pins just for curiosity's sake.

 

[Konrad]

With you not getting a response at 4.6 and lower voltages leads me to think there is a solder bridge resulting in a voltage divider some where in the RX. I now the servo will respond with voltages at least down to 3.2V. I also now that most (I haven't tested the GR6) Fr Sky RX perform at voltages below 3.55V.

I think you have given this RX a good shot. Return it to FrSky for warranty, or just to give then a data point for the quality matrixes. Nobody has a 100% perfect manufacturing record, but it is how a firm deals with issues that is the key to customer satisfaction.

 

[Landru]

Thanks, Konrad. Seems like good advice.

@Wayne, can I send you this receiver for warranty purposes? Or, should I try anything else first?

 

[Wayne]

Yeah, we will need to get it back and get you a replacement. I'll send a link to this thread to some other dealers and FrSky so they can see this one. Never know, they may have run across it before.

Silly question, same results with a different servo? (Not X06) I would expect it to be the same..

 

[Landru]

Wonderful! Thank you.

I'll follow up via email in the next few days when I've posted the receiver to you.

The totally weird thing is that I have only been able to reproduce the glitching with X06 servos. It happens on all four I have on hand. And it has never happened with the two X08, an FrSky 5611 HV, and old analog GWS I tested on the GR6. All four of my X06 worked properly when tested with a GR8 and a G-RX8.

As noted above, the GR6 did fail to power up sometimes even with no servo attached.

 

[Landru]

Footnote
Before packing up the receiver for return, I tried a few other digital servos: Corona SB-6033, Hyperion DS09-AMD, another X08v5, and a MKS-DS-450. All worked as expected except for the MKS, which caused the GR6 go in and out of failsafe continuously even without a load on the servo or a command for it to move.

 

[Wayne]

Yikes!

 

[HENNY]

Footnote
Before packing up the receiver for return, I tried a few other digital servos: Corona SB-6033, Hyperion DS09-AMD, another X08v5, and a MKS-DS-450. All worked as expected except for the MKS, which caused the GR6 go in and out of failsafe continuously even without a load on the servo or a command for it to move.

What Bec or battery are you driving the GR6 and MKS servo from. You may be requesting too much current which is causing the supply voltage to drop to near or below 3.3 volt momentarily.

 

[Landru]

It was just a quick test for curiosity's sake before I popped the receiver in the mail. As I recall I used a set of freshly charged NiMH (4xAA).

What I found particularly odd was that the MKS servo was under zero load. It was a brand new servo removed from it's sealed box and plugged into the receiver. And nothing else was plugged into the receiver -- apart from power, of course.

The GR6 is with Aloft now, I believe. I'm very curious if they can reproduce any of the problems. Having tried a good handful of different servos and various different power sources, I'm stumped.

 

[HENNY]

As I recall I used a set of freshly charged NiMH (4xAA).

Freshly charged doesn't mean its a good battery pack. To be sure and part of the fault finding procedure you also need to check the battery pack voltage under load. There are NiMH battery pack load testers available. We recently had had a person at our field crash after only a minute in the air. He said the 4 cell battery was charged that morning but after recovering the battery it measured 4 volts with no load.

 

[Landru]

Yes, I hear you. I've also seen convincing evidence that very brief voltage fluctuations in some NiMH cells may cause uncommanded servo movements. That was a real eye-opener.

It's been many years since I've used NiMH in RC. I'd never use them to power any mission critical device again.

The issue with the MKS servo might do with further investigation. I investigated the weirdness with the KST X06 more thoroughly and found it occurred with various DC power sources.

 

[Reto]

Once I made a similar experience with a NiMH battery and a new high performance servo. The problem was a simple old power switch cable between battery and receiver. Obviously the additional resistor of the old switch was too much over all.