DiscoWings

My Feedback: (76)

There is a big discussion on F/G regarding issues people are having with the latest futaba rx, the R7018SB. It is having a problem with some brushles servos and is frequently going to lock out. Yesterday someone lost a jet. Be careful, I found some videos:

https://www.youtube.com/watch?v=krif9snAaY0

https://www.youtube.com/watch?v=cwagbh6CIeo

https://www.youtube.com/watch?v=KxCR_on9BFE


despite having 2 deans plugs the rx is rated for 12 amps with a 20 amp peak and a warning is included saying not to use more than 6 HV brushless servos!

Jgwright

I see that the servo tested are of the highest torque available. 541 oz in for the HBL380 and 611 oz in for the Hitech. It is crazy to expect a standard receiver to cope with them. Just look at the current draw the HBL quotes 5.8 amps at 7.2v for EACH servo. I do not have the figure for the Hi-tech but I would guess that it will be over 6 amps. The standard servo lead plugs are not suitable for much more than 4 amps and will get hot if running at 4 amps continuous. Before you get too excited just think about it a bit... if you really want to drive such huge power servos then you need a better interface like a Powerbox. Also all the pugs that plug into the Powerbox should be of Mutiplex type to take the current. I am not aware that any of the PowerBox range is designed for such servo connections even if it could cope with the current draw from multiple high power servos.

John

Jgwright

One other thing, the Tx also plays a part. You do need to be operating the servos in the correct mode and it is necessary to program the correct mode in the Rx before connecting up the transmitter. If you use the FASSTest high speed mode with the 18 SZ then you only have 12 channels. If you use the normal mode FASSTest then you get all 18 channels. As I discovered if you use the high speed mode with cheap servos they will glitch a lot, change to the standard mode and it goes away. I do not have any ultra High speed high power servos but I bet the reverse happens if they are used on normal mode. Not sure if the guy in the video with his 14 SZ has High speed FASSTTest mode available on his Tx that he was using.

John

modtron

Before making waves - it would be better to see the test done with Futaba servo's.
Futaba do not have to consider the use with other manufactures equipment and why should they !

modtron
Oxford UK

bluescoobydoo

when I saw this the first time it gave me the impression that with the twin inputs that it would not require the user to go to powerbox for anything else but I guess it is just a normal receiver with twin inputs, I would hope that orbit might bring out a powerjack for it soon but if they did that it would be the same as a 6014 with a powerjack fitted so I don't see where they are going to improve anything?

Jgwright

It has higher power levels than the 6104 and will handle 2 X 2 cell Lipo directly to it and higher voltage to servos, so need for any Powerjack interface.

For smaller jets there is no need for a Powerbox or a Powerjack. I have fitted a Mick Reeves Venom with one. My only dilemma was using a mix of cheaper analogue servos as to whether I could feed the A123 batteries directly to the servos. In the end I opted for a regulator, but was probably not necessary. If you are sure your servos will handle the voltage directly then this is a big step up from the 6014.

John

dvcam99

Hello together,

this situation was already discussed in the German Futaba Forum some days ago. For those you can read and understand german you can find under the following link and post #83 a analyse from me of the situation with R7018SB.

http://www.futaba-forum.net/showthre...ighlight=R7018

To make a short summarize:

1. You can have the situation that a servo could work as a generator instead of a load. This depands on the internal servo design.
2. The R7018SB has two semiconductor diodes installed internaly in order to decouple and switch between the two batteries. This is a common industrial practice.
3. If you have decoupled the batteries from the servo side, the batteries can not buffer anymore energy generated by a servo or group of servos.
4. Under the above link you can see a high energy voltage burst (scope Screen shoot) on the receiver power rail.
5. If the amplitude of this burst is big enought, every microcontroller receiver will reset and restart. Big Problem if your modell is in the air.


On order to make a long story short. Connect a 4700uF 16Volt capacitor to the recieiver plus minus power rail/connectors.
Please pay attention to the correct polarity of this capacitor and the correct connection to the Pins.

The Problem will be solved

There are many examples on the web for these kind of receiver capacitors.

BR
Dirk
CB Elektronics

Eddie P

My Feedback: (4)

I've read in multiple places, perhaps not Futaba's own words, that the consensus was the traditional high servo count, high power servo setup would absolutely depart from the design spec of the receiver to use it's native bus to power all those servos. This is still just a receiver. Powerbox, Smart Fly, other power distribution electrical bus absolutely required in the applications we mostly see in RC jets (let alone the bigger jets common today).

The receiver was set up as a self contained, redundant setup for "traditionallly" sized aircraft without having to feel like they should resort to a 3rd party redundant high power distribution board and then there was the list of advanced capabilities it has that many won't even know what they are or how they would benefit us (me included). I bet a P-60 sized sport jet would be fine on this alone but I still would use a Smart Fly board, myself!!

Eddie P

My Feedback: (4)

I have to admit, I don't understand what the deal is with the servo test videos. They are operating and he is losing the link on the table? I'd be more interested if he ran the tests installed in a plane conducting a standard range test at the field in proper conditions. There could be a lot going on in his particular space that might lead to false issues. But for the sake of argument, let's say in fact there is an issue and that his particular case is being addressed. Perhaps a defective unit, whatever. What is the feedback so far from Futaba or other sources?

ron Sweeney

As a total layman I find it terribly disconcerting that the rx to servo link has become so complex, and problems have been experienced first at the customer point. Has the day gone where I can buy a receiver and link a servo without worrying about the match? I have spent a lot of time and frustration trying to work out problems with Futaba miss matches. I am told that certain makes of servo are not compatible with the 14 ch rx and that is the servo manufacturer's problem. Not in my book. I still find their manual and instruction sheets bordering on gibberish and before anybody remonstrates just check out any of their literature and find out how much poor grammar and really bad translation exists in the text. If anybody checking the initial drafts hasn't seen these glaring issues then I can see that nobody cares about the customer. Over the years there have been several attempts at translating Futaba manuals into understandable prose but the mentality behind the software writers seems to be at odds with the common man. I have several different types of transmitters and I am in a position to compare. The only Futaba software that was logical was the Zap. I admit that I am old and loosing my faculties but I find that other Futaba users in my club share my opinion. Ron.

Hinckley Bill

My Feedback: (569)

Not sure if the 'issues' will effect my setups in larger size (40% +) aircraft but sure not going to chance it....contacted Tower Hobbies and was told to return as defective.

They won't have to tell me twice, as it went back in this mornings mail!

Eddie P

My Feedback: (4)

Good move!!

I agree with you. For example, I have yet to have S Bus explained to me to the point where I don't any longer ask myself if it's a bit of a Rube Goldberg solution for people like me that don't want to get trapped into a specific brand of servo. But hey, that's just me. I suppose I just might have not been asking the right questions...

dbsonic

My Feedback: (3)

I think what Dirk wrote makes a lot of sense to me. I'll be checking out that forum as it looks like there is quite a good thread there.

FenderBean

I posted about this same exact thing on FG. It's not practical application for a large 3D plane or large jet with lots of equipment.

Westwindpilot86

Hey everyone, sorry to bring back an old thread. But its better than starting a new one. I have a relatively new futaba 7018sb. I have been told by Nick Maxwell himself that the RX is perfectly safe to use with-in its limits. Which is no more than 6 HV High Torque servos. If I can run it I would be powering 8 Jr 8411 servos on 6 volts. Anyone see any issue with this?

dbsonic

My Feedback: (3)

I'd test it thoroughly first on the bench before flying but would also add the decoupling cap as Dirk posted.

Zeeb

My Feedback: (41)

It's not Nick's money you're playing with, just 'sayin......

I sent mine back to Tower when the problem showed up.

Westwindpilot86

I didnt buy this reciever. So kind of hard to return it.

ravill

My Feedback: (11)

If the airplane I was putting costs more than a receiver I'm willing to use in it, I'd say that's my minimum requirement. I would use that rx for lead shot practice.

Zeeb

My Feedback: (41)

Not suggesting you try to return it figuring it's been so long since the fiasco, that you didn't buy it new. I AM suggesting that you not use it, it's a really poor design.

LGM Graphix

My Feedback: (22)

Your 8 8411 servos are worth more than a new receiver alone never mind the airplane. Why would you risk it? I would certainly never say you should be fine. I'd be looking at it as a very high potential for failure.

Auburn02

My Feedback: (1)

I definitely wouldn't trash it as some have implied. Hey, foamies need receivers too.

ravill

My Feedback: (11)

Indeed!

But, hey, shotguns need targets too! LOL

gunradd

My Feedback: (9)

dbsonic

My Feedback: (3)

Alternative, if you are only going to use 8 servos then you could get any of the 6xx8 series. new r6208 maybe. $129 in stock at Tower.. maybe worth doing instead.