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FUTABA T8J center throttle - UPDATE: PROBLEM SOLVED!

Discussion in 'General Discussion' started by PhantomFan, Nov 5, 2013.

  1. PhantomFan

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    OK...so I converted my Futaba T8J transmitter to a self-centering throttle to match the manner in which the v.1.1.1 Phantom transmitter is supplied. I GREATLY prefer this arrangement and made the conversion in part because I'm going to install a Futaba Rx into the Phantom as a next step. The problems that have now arisen are two-fold.

    Problem one I have created is that the the transmitter alarms because the throttle is not at zero. This is a standard warning with the Tx. Pretty sure I read how I can over-ride this by pressing and holding the + and - or some such.

    The greater problem by far is with the NAZA Lite that is installed on my OFM Jumper 600. The NAZA-M lite Assistant software is giving me a <<CFG_ERR>> or configuration error. Clearly, it ALSO is showing concerns that the "centered throttle" is not being perceived as the zero throttle set point. How do I overcome this? Do I need to calibrate the transmitter? I know how it is done with the Phantom transmitter, but what is the procedure for properly calibrating the Futaba? Or is the answer more a more complicated matter of settings in the Futaba T8J????

    I need explicit instructions/guidance. I've never done this before, but I KNOW others have. What in heavens name do I need to do???? Once accomplished I can put the Futaba receiver in the Phantom and program the Tx for both craft.

    Please HELP me if you can!!!

    Thanks in advance.

    PF
     
  2. PhantomFan

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    Re: FUTABA T8J converted to center throttle - now need help!

    Update: I MAY have solved my own problem...at least the more thorny of the two and the one that gave me the greatest functional problem. Trouble is, I'm not sure which of the remedial steps I took actually resulted in the cure. :oops:

    I diddled with the throttle (channel 3) end points on the transmitter which now read 100/0 instead of 100/100. Afterwards I re-calibrated the sticks in the Assistant software with the OFM Jumper 600 attached. The Assistant software now shows the throttle to be in the lowest possible position while the throttle is actually physically centered, and then it appropriately throttles up to 100% as the throttle is advanced to full. That's how the Phantom v.1.1.1 software reacts.

    I removed all four props, and powered up the the Tx and the Jumper on the bench. Other than the non-zero throttle alarm, things seemed perfect. If I throttled up within the first three seconds, the motors went from idle to full. If I didn't touch the centered stick after performing the CSC, the Jumper motors shut down, precisely as they should. Now that I think about it, I should have tested whether they shut down AFTER start up if I do throttle up and then allow the throttle to re-center itself for > 3 seconds. If so, that would be a disaster. I'll test that on the ground tomorrow, or take the props off again and bench test again.

    While I had the Jumper props off, I went ahead and balanced them. Unlike the cheapo props I bought for the Phantom, these needed only minimal tweaking to be perfectly balanced. Two needed no sanding at all.

    So...I may have bumbled my way to a solution...but maybe not. I'll know better tomorrow. It's after 12MN and I have an early starting day tomorrow.

    PF
     
  3. Gizmo3000

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    Re: FUTABA T8J converted to center throttle - now need help!

    curious, but did you follow the online video's on how to install the T8J?

    the throttle alarm on the Tx is only a minor thing to deal with. when you turn on your Futaba and the alarm goes off,. merely lower your throttle stick down to 0% for a sec and release.
    not sure if there's a preference to turn it off, but it's there only so that people with RC planes and other "less intelligent" craft won't spin up and take off accidentally. with the NAZA of course, there's no possibly danger in doing that since the motors have to be armed.
     
  4. PhantomFan

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    Re: FUTABA T8J converted to center throttle - now need help!

    I've been flying the Jumper 600 with the Futaba and the unmodified throttle - where it stays DOWN for zero throttle) for about 10 days. Once I received the throttle spring and two plastic parts to convert it to center stick, I made the modification.

    Once THAT was done, I could not arm the motors, and the annoying Tx alarm would sound and the timer would start counting down the instant I turned it on. So...I made the end point changes listed above to throttle 100/0, and now I can arm the motors and the Jumper APPEARS to behave identically in the NAZA Lite Assistant software as the Phantom does in the DJI NAZAM Assistant 2.18.

    I may field test it in a few minutes. I'm curious as to whether the motors will keep running or shut down with the center stick pegged in the middle with an end-point designation of ZERO. :?

    EDIT: OK...as feared, the Jumper falls out out of the sky and the motors shut down when the throttle is allowed to self-center. I tried to bring the lower endpoint up to 20% out in the back yard (obviously w/o doing any IMU calibration after the change) but it made no difference. I'm going to try +100 and -100 as endpoints and then re-calibrate. Wouldn't that be the same as center = zero?? Maybe I can do that at lunch time. That's my final guess as to how to make this work.


    ARRRGGG. Zero is as low as you can go. The Tx will not accept negative end-point numbers in throttle. There goes THAT idea.

    PF
     
  5. Peter Patricelli

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    Re: FUTABA T8J converted to center throttle - now need help!

    Man, I am not in a situation of expertise on this.....but I have the self-centering throttle model from the beginning.

    Seems to me you are making a big mistake....the self centered position is NOT zero. Zero is ALL the way down. Middle position is something between 20-50% Next time I have the assistant connected I will see what the setting is but ZERO is SHUTOFF POSITION!! As I think you experienced.

    The middle position is LESS than take-off power...after starting the motor. The middle position means HOVER....once the take-off has occurred....which is considerably more power than it was before take-off (or maybe sitting on the ground IS hover...there on the ground. One can adjust the middle position in the stock TX and Assistant....but it is NEVER zero.

    I have NO idea how to set that in a new Futaba.
     
  6. PhantomFan

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    Re: FUTABA T8J converted to center throttle - now need help!

    Well, frustration, impatience, and gorgeous flying weather caused me to put the Tx back to how it was originally supplied, with a throttle that stays down rather than self-centering. I just don't get it. Why can I fly center-stick with the stock v.1.1.1 Phantom transmitter and have the benefit of being able to replicate that setup on a Futaba T8J - a far more sophisticated transmitter???? Makes no sense to me.

    Oh well... :roll: Set it all back to the way it was, and took this puppy out for a spin. The Phantom too, for good measure. Windless, sunny and 60 degrees here.



    PF
     

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  7. The Editor

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    Re: FUTABA T8J converted to center throttle - now need help!

    Ok, I am VERY confused by this thread (not hard to do but still I'm confused)

    First of all - Yes I fly using a Futaba T8J
    Second - Yes I have done the mod for sprung loaded throttle stick
    Third - You do not need ANY additional parts or anything to do the modification (simply take the back off the TX unscrew the black plate covering the throttle and either turn it 90 degrees as I did or remove it completely and throw it away if you wish) - Mod Done!
    Fourth - Once the mod is done you do not need to calibrate or set ANYTHING. If you think about it you have done nothing more than release a spring under tension that now makes the stick return to center when you release it. It is no different to you turning your non modified T8J on when the stick was in the center position - you would still get the 'throttle not down alarm'. The only difference now is you physically have to either hold down the throttle when you turn the TX on or just turn it on and push the throttle to minimum to silence the alarm.
    The functionality, travel, setup and calibration have not changed at all !
     
  8. Gizmo3000

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    Re: FUTABA T8J converted to center throttle - now need help!

    +1

    Messing with end-points so drastically is a bad idea.
    sprung or un-sprung throttle should produce the same results - 0% throttle Phantom wants to go down, 50% Phantom hovers, 100% throttle Phantom goes up!

    Tho I'm curious how you managed to do the center-sprung throttle without ordering additional parts from Futaba
    it's my understanding that the only way to properly do it is to contact Futaba, and they'll send out additional center sprung parts for free. (tho people in the UK have to pay for it)
     
  9. The Editor

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    Re: FUTABA T8J converted to center throttle - now need help!

    Nope! - I'm in the UK and no coins crossed anyone's palms :lol:

    Since the mod only involves taking bits out and not adding or putting bits in there are no additional parts needed.

    All that needs to be done is:
    1. Unscrew back cover and remove
    2. Unscrew two small screws holding black plastic plate in place that covers the back of the throttle gimbal
    3. Re-secure back cover

    That's it!

    The black plate has a pin extending from it which, when in place pushes against a lever that compresses the gimbal spring. On removing the plate, the spring/lever is released and you have a sprung stick. I have also tried reversing the procedure and it works fine.

    Optionally you can (as I have) elect to turn the plate through 90 degrees and screw it back on. The only reason for doing this is I would lose the plate and if one day I ever wanted to convert it back to non sprung I would never be able to find the bloody thing again :D .
     
  10. Gizmo3000

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    Re: FUTABA T8J converted to center throttle - now need help!

    Hmmm,
    While I'm not disagreeing with you.. I know for a fact (from reading this forum and others), that numerous people have contacted Futaba and been sent parts to convert their T8J's to self centering (viewtopic.php?f=5&t=1352&p=11133&hilit=t8j+center#p11133).
    They've sent owners the parts for free,. although one guy in the UK said he'd have to pay a fair amount for it.
    I've not done so myself (I prefer the old style throttle), but in a google search it says on Futaba's website
    "We may be able to modify your radio in this manner for you, please contact Futaba Support at 217-398-8970 or by email at support@futaba-rc.com to find out if your radio can be modified."
    so I suggest anyone wanting to convert should contact Futaba and get the parts, especially since it's probably free.

    One thing I also just discovered is that apparently the T8j has gone thru some changes over the year or so.
    i came across this video http://www.youtube.com/watch?v=RQ6ouHCtvXY
    showing how a guy is removing a back plate, which sounds similar to what you're describing.

    But the T8J that I own (circa March 2013) does not have such a plate to remove or anything, the little ratchet/non ratchet part is right there exposed being held on by a single screw.

    So perhaps we're both right, maybe in older T8J's it was easy to do so, but in newer T8J's it requires ordering the parts.
     
  11. PhantomFan

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    Re: FUTABA T8J converted to center throttle - now need help!

    My Tx is the exact same as Gizmo3000's. There is no back plate (I've seen that video!). What it took to modify my transmitter stick is the insertion of a small bit of articulating black plastic which acts like a rocker or lever, a tiny spring, and a bit of plastic to be mounted on a post to one side of the stick that provides tension on the spring that is transmitted to the rocker piece that centers the throttle. Sounds FAR more complicated than it actually is.

    There is no way that the Jumper/NAZA-Lite could be operated without re-calibration after a center-stick modification. NO FRIGGIN' WAY! Just think about it. The software has no idea whether the stick is centered by a spring or the intent of the pilot! That mid-point throttle means GO BABY, GO!!! to the motor RPM. You start those motors and then "release" the throttle to the spring loaded center and your quad will ascend out of sight in about 2 seconds flat. Ask me how I know!!!!!!!!!!

    That's the experience that had me back on the work-bench reversing the modification. :eek:

    PF
     
  12. The Editor

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    Re: FUTABA T8J converted to center throttle - now need help!

    Good theory except for one thing..... I purchased my T8J in August of this year (after I got the H3-2D in the first week of July). I purchased it from a main Futaba dealer here in the UK.
    That aside, I do not dispute there may be different versions of the T8J and if a manufacturer can see a way of making some more money they will so that's probably the case.

    To PF.......However what I cannot see is how changing from non-sprung stick to a sprung stick changes any settings.
    IT DOESN'T PERIOD !

    The travel of the stick remains the same
    The values from the potentiometer remain the same from zero to full throw
    The Naza doesn't care if you have a sprung throttle lever or if you have rubber band round it - it is simply getting it's data values from the RX which in turn is getting it's data from the TX.
    Nothing in the data stream has altered.
    Think about it.... One day you have a non sprung stick and everything works fine. Then you turn off you TX and put two rubber bands round the throttle stick, one loops over the top and round the lever and one loops over the bottom and round the lever. Now your throttle stick returns to center when you let it go because the rubber bands make it ping back there. That exactly what the mod does.
    You say that the center positions means 'Go baby go' but it doesn't... It means hover!
    Are you saying that's basically what happened? If that is the case there is something seriously wrong with your set up or you have done the modification incorrectly or altered something unknowingly.
     
  13. Gizmo3000

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    Re: FUTABA T8J converted to center throttle - now need help!

    I have another theory then.. maybe it's the difference between Futaba USA and Futaba UK!?
    as I know those in the UK have reported that their Futaba's come with battery packs
    whereas here in the US, instead of battery packs, we get a 4xAA battery holder. go figure.
    they've sent the parts to US buyers for free as well.

    and I def agree, no matter how you physically alter it,. 0-100% throttle should behave the same regardless!
     
  14. The Editor

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    Re: FUTABA T8J converted to center throttle - now need help!

    You're right - I DID get a rechargeable battery pack and charger with mine as well as a little spring lever to change the throttle stick from a ratchet feel to a smooth feel if I want to. It also came with TWo Rx's - One RS2008B and a R2006GS (which I have never used). Just the way they are marketed in different regions I guess.
     
  15. PhantomFan

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    Re: FUTABA T8J converted to center throttle - now need help!

    Ummm...maybe in NAZAM in combination with a Phantom it does, but sure as hell >>NOT<< with the Naza Lite in combination with a Futaba and OFM Jumper 600. With THAT setup what you wrote makes absolutely no sense, because here is how it seems to operate: Throttle (held) all the way DOWN is idle motor rpm of (lets say) 500rpm and full UP is 20,500rpm (again, just picking a number here for demonstration purposes). It's pretty damned obvious that smack in the middle the rpm is going to be 10,000rpm. That fixed rpm does NOT translate into "hover". Depending on the weight of the craft (and numerous other values, I imagine) it might drop like a stone or climb like a bastard. Releasing the held-down throttle to allow it to go to center caused my Jumper 600 to climb out so fast I hardly had time to react.

    I agree that with the Phantom and stock (self-centering throttle of v.1.1.1) what you say is absolutely true. You will just have to take my word for it that the NAZA Lite, in combination with a self-centering throttle on a Futaba T8J and a OFM Jumper 600 functions completely differently. It is a complete mystery to me why I can't get the later setup to mimic the former...but I can't, nor has anyone else been able to suggest a way to get it done. :cry:

    What kills me right now is I have no "hover" to speak of when I fly. The tiniest increment forward or back in the throttle causes the Jumper to climb or to drop. ..and it never stops climbing or dropping. In order to get a hover at any given throttle position, I have to use the electronic trim. If I go higher, I then have to cut back to "best hover" possible with the stick and then re-trim. IT SUCKS. THat is why I'm working so hard to get the Futaba to emulate the function of the v.1.1.1 DJI transmitter. Furthermore, as the battery power drops, it takes more and more UP throttle to keep the Jumper at altitude. Again, THIS SUCKS, and can't be the way it's supposed to be!!!!

    PF
     
  16. PhantomFan

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    Re: FUTABA T8J center throttle - STILL need help! w/screen s

    Screen shots of NAZA Lite with non-centered throttle. As you can see, left is idle/low throttle, black arrow to the right is "full" throttle. The Phantom screen shot looks NOTHING like! that
     

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  17. Gizmo3000

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    Re: FUTABA T8J center throttle - STILL need help! w/screen s

    Naza Lite?
     
  18. The Editor

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    Re: FUTABA T8J center throttle - STILL need help! w/screen s

    OK - I'll get to the bottom of this if it kills me.
    I'm still confused (like I said not hard to do)

    Right - I have my cup of tea (very British)...... Let me understand a few things first. Are you saying:

    1. Your Futaba worked fine with non - sprung stick on both your Phantom and Jumper 600?
    2. When you did the sprung stick mod it started playing up on the Jumper 600 but NOT on the Phantom?
    3. When you did the stick mod did you try it out without doing any calibrations or anything or did you go straight and do a calibration?

    Take me through the sequence of events.....
     
  19. PhantomFan

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    Re: FUTABA T8J center throttle - STILL need help! w/screen s

    Sequence is as follows:
    I purchase and fly the Phantom v.1.1.1 with its stock Tx with self centering throttle. It works flawlessly, and I love and prefer that setup and its benefits...the spring-loaded center stick which allows for hover at any altitude just by letting go of the sticks. Brilliant arrangement IMHO.

    I bought the Jumper kit and Futaba T8J which arrived WITHOUT self-centering stick. Jumper came with NAZA-Lite (see pix, page 1 this thread). Installed everything and flew the Jumper. The screen shots accurately represent the manner in which the NAZA-lite interprets the throttle posistion of the Futaba, with down stick being idle, full up being high RPM. I flew and trimmed it all out, but disliked the non-centering throttle. [aside:] I ALSO bought a second Rx for the Futaba to install in the Phantom as an "upgrade" and to fly both quads off of one transmitter, but have not yet swapped it. The Phantom is still 100% stock.

    I acquired the Futaba radio parts to make throttle self-centering, install them, and re-calibrate the sticks in the NAZA-Lite software (my only choice for the hardware in the Jumper). First go round the motors won't even arm no matter what CSC move(s) I make on the Tx. I re-attach the Jumper to the NAZA lite after this "non-event and see a <CFG-ERR> message, so I go through the whole software setup looking for a problem and find none. I save each "page" to the MC per the manual which seems to work fine. The screen shot (above) representation of throttle remains the same, despite the fact I've re-calibrated with a Tx converted to "center-stick". When flown it is a ****-show..but at least the motors armed. The Jumper's response to throttle is linear, as if I were flying a one-prop airplane. I have to hold down the throttle to keep the motors at idle speed and prevent the craft from accelerating up to the International Space Station in about 2 seconds flat! When released to center on spring power (not by intent of pilot) the Jumper interprets this self-centering as "go up as fast as imaginable!"...which is what it did, freaking me out.

    After that, I started "messing" with the Tx throttle values with props OFF the craft to see if I could find some magic settings that would cure that behavior. Found none, and re-set every value back to normal 100/100 on the Futaba Tx.

    Hope that helps.

    PF
     
  20. PhantomFan

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    Holy $HIT!!!!!!!! I figured it out!!! Never in a million years would I have thought THIS was the problem.

    It turns out that my state-of-the-art eight core (six of which are unlocked and overclocked) desktop computer which I bought for fractal rendering with Mandelbulb 3D, Fragmentarium, Fractal X-treme, etcetera was sending the stick calibration data stream to the NAZA-lite MU >>>>>>SO FAST<<<<<< through the for-**** (probably 32 bit) Assistant software, that it was utterly incapable of properly recording/passing on the data stream. Thus, the data was corrupt upon arrival.

    My first clue (dumb old me for ignoring it!) should have been the <<CFG-ERR> the software consistently displayed. I discovered the true nature of the problem when, by accident, I made some exceedingly small, extremely slow stick movements on ONE stick and noticed the calibration response seemed unusually "appropriate" - smooth and not herky-jerky like when I moved multiple sticks around simultaneously as I have seen done in the tutorial videos. Then the #$%#@ light bulb went off!!!! Holy crap!!!

    I used the external switch on my Lenovo to reduce the core speed to minimum, then went into the software management program and "dumbed" it down even further. Then I re-opened the NAZA-Lite program and did the stick calibration (center-stick spring re-installed) ONE stick at a time with excruciating, snail-like slowness - as slow as I could possibly move my hand. IT WORKED!!!! The calibration recorded appropriately to all four channels, and I ended up with four green arrows centered exactly as when the Phantom is configured. Most importantly, there was NO <<CFG-ERR>> message!!! Joy and hopefulness returned!!!

    I took the Jumper outside, and lo and behold it WORKED!!!!!!!!!!! So, the friggin' antiquated software (NAZA-Lite) which should work fine on a 20 year old computer is utterly incapable of keeping up with the processing speeds and data stream generated by state of the art computers. LESSON: If you purchase the NAZA-Lite, be prepared to install the Assistant software on some old for-**** laptop to avoid problems. Calibrate ONE stick at a time, and calibrate as slow as humanly possible.

    Many, many thanks to those who followed this thread and offered their assistance!!!! Luv ya!!!

    PF