3GX and MKS92 issue

[BgBrik]

Help please; I am running a 450DFC with a 3GX, 3xMKS92 servos and a CC10A bec set to 6V

Every now and again when I switch on one of the servos (usually the Ail but not always) does not operate. It is as if it has no power or no signal, ie I can easily turn it. Switching off/on usually cures it.

This issue is not servo dependent as I have seen it happen on different servos and swapped them round.

Until today I just put it down to "one of those things" but this afternoon whilst hovering at a few feet it just nosed in so I feel I need to follow this up.

[coolice]

Hey.

When you power on and the servo sometimes is lifeless, has the radio actually bound? The first question I should ask is are you using Spektrum sats connected directly to the 3GX and if yes do these light up solid when you've noticed this problem?

I have seen it where the 3GX doesn't initialise properly sometimes and a quick reconnect fixes the issue. This is due to how the 3GX is expecting to see power by a certain point and whem it doesn't it doesn't bind.

Also when the model did go in, again did you notice if the spektrum lights were flashing?
.

[Chris Boughton]

Hi dude this isn't anything to do with your problem but seen as ur running these servos I thought it was worth mentioning the MKS DS92 servos are not actually rated for 6v their packageing was wrongly labled and its only safe to run these servos on 5.5v as ive gone through 3 tht have just burnt out for no reason.!! As quoted by MKS "
To all of you MKS DS92 users please pay attention to the following safety notice from MKS Servo Tech:


“Dear Customers and pilots
To avoid the problem for voltage use and acknowledge, please notice there is a limited range of voltage use when purchasing the following MKS servos :
Wing series：DS6125 / DS6125MINI / DS6125H / DS6188
Micro series：DS92
RTR/RTF series：DS1210 / DS1009
For above lists servos:
1.Operation Voltage must be on：4.8~5.5V
2.Only use 4S NiCd / NiMH battery
3.Do Not use Lipo battery
4.Do Not use when use BEC and output 6.0V
5.The spec (Torque / Speed) at 6V will not be offered anymore.
We will revise to correct data as soon as possible for above servos in website or packaging. To ensure your use safety, please must follow this direct of voltage to use.
Thank you a lot!”

[BgBrik]

Thanks Chris, I just found that info whilst searching for problem with MKS servos!

Thanks Coolice, Yes I am using a Spektrum Satellite and it is binding correctly and lights solid. The issue is reproducible on the bench every 5 or 6 turn on. I have done a lot of swapping components around and concluded that it’s an issue with the CC BEC and the servos as I cannot reproduce the problem when going back to the built in Align BEC or with using other makes of servo. When looking at the signal wires on a servo that’s not working using an Oscilloscope Gnd, Power and Signal are all correct.

I will now go and reduce the voltage and try again.

I am beginning to wonder if my crash was a completely separate issue. When I picked up the Heli the battery was unplugged and as the leads were not under tension I'm thinking that maybe I did not push the connectors together fully (under pressure as I was demonstrating it to a load of school kids at the time, just shows that you can never be to careful!)

[BgBrik]

Looks like it’s a known problem, see: Cause for servo cut out - HeliFreak

CC BEC and MKS92 servos, the suggestion is that a power surge as all three servos initialise results in some of the servos not initialising properly-what’s annoying is I just spent a lot of money on that BEC and associated programming device.

[coolice]

Hey.

Ah that's interesting to know, as the MKS are quite desirable servos on the 450's and the CC BEC is a logical choice for this model to due to it's size.

I wonder if the new CC Edge 35 ESC with inbuilt CC BEC will suffer the same problems?
.

[BgBrik]

so what do I do now? Make sure all servos initialised before I fly, or change something?