DX7 screen shutdown

[jaron]

I use the Spektrum DX7 for a couple of month now and it is, despite some design flaws, the best investment in heli stuff I've ever made.

But just to report it, as others already have: today the screen of my DX7 suddenly shut down - while the heli was still on the ground. The transmitter was running because I could hear it buzzing. Sadly I didn't check if the connection to the receiver was still working because I was shocked and turned the transmitter off and on again (that solved the problem by the way).
But now I am asking myself how can you trust a remote control if there is a thing in it that just shuts down without any noticeable reason?

[DavidH]

The transmitter was running because I could hear it buzzing.

I have never heard a transmitter that made a buzzing sound when it is on.
Why does the transmitter buzz when power is on?

You can read, there is several reports of different problems with the screen on the DX7. None of them have had any effect of the functionability of the radio for flying the model.

David

[dutch_anykey]

yeah it's odd.
I had reversed screen and blank screen as well. A few weeks ago i had "BACKUP ERROR) had to send it in for repair
And despite all that....i wouldnt want another radio at this moment. (not in this price range i mean....)
All of this is happened during power-on's of the radio. It never failed on me during flight. not a single glitch. (except for the elevator lock when i was about to take off...but that was the known ar6100 bug and not related to the tx)

Maurice

[jaron]

David, it was that (normal) humming sound of the DX7 that makes you fell your hands are getting microwaved. I haven't read all the threads/reports on the screen issue and I'm glad to hear that this has no effect to the functionality of the DX7.

[soundgodz]

I don't get any kind of vibration in my dx-7
Maybe yours has a problem with the power supply and the screen is the first sign of failure.

[DavidH]

I agree, I have never felt any type of vibration or heard a hum from any transmitter I have used. Sounds like there could some type of problem.

David

[Finless]

DX7's do buzz at the RF area of the TX. Dont ask me why but they do. Usually you cant hear it outside but you can inside when it's real quite. Some seem to do it more than others but I never saw one you could FEEL the buzzing.

I have seen some peoples DX have a reversed screen, blank screen, and garbled screen. But mine has yet to do that to me but I have seen others do it.

I like the 2.4 and the freedom but I still dont like the cheapy radio. I CANT WAIT to get my FASST module for my 14MZ and covert all my stuff again :)
I should have no problem selling off all my DX stuff to help pay for the conversion :)

Bob

[Danal Estes]

They buzz because they are not transmitting RF most of the time. They transmit a very brief pulse when they have data to send and then wait with no RF until more data is available (another frame). Just so happens that the frame rate is in the audio frequency of human hearing. What you are hearing is all the traces on the circuit board, and other components, moving very slightly as they power up/down during each RF burst.

Really.

[drummer5140]

Danal, Thanks for the titbit on the dx7 workings

[stevehonn]

Mine buzzes louder when you switch it on, then it settles down after a few seconds, the voltage drops at this time too then rises. I guess the transmitter is working hard scanning for vacant frequencies at this point.

[heliboy88]

DX7's do buzz at the RF area of the TX. Dont ask me why but they do. Usually you cant hear it outside but you can inside when it's real quite. Some seem to do it more than others but I never saw one you could FEEL the buzzing.

I have seen some peoples DX have a reversed screen, blank screen, and garbled screen. But mine has yet to do that to me but I have seen others do it.

I like the 2.4 and the freedom but I still dont like the cheapy radio. I CANT WAIT to get my FASST module for my 14MZ and covert all my stuff again :)
I should have no problem selling off all my DX stuff to help pay for the conversion :)

Bob

Hi Bob,

First of all, i would like to thank you so much for your videos, it really helped a lot of us here.
Just wanna ask for your opinion about the FASST module for my 9C. Cus i've heard that the ccpm operation of the 9c is poor. Also, when using a 2.4G module with the 9c will even make the slow response of the 9c even worse. Any advice sir? Do you think i should get a dedicated 2.4G radio or it's ok to get a module for the 9c?
Thanks in advance for any advice and tip i can get.

Best regards,
Rich

[Finless]

Yes the 9C is showing it's age now I think. eCCPM and PPM mode has a latency of 65 and the DX7 is about 26. I dont think the FASST module will help this to be honest.

Now many will ask, can you really feel this latency? My answer is YES at least for me. But not everyone may. So I aint going to tell you to toss out your 9C and get a cheapy DX7. I like 2.4 but I still dont like the limited capabilities of the DX7 or it's cheap feel. I also dont want to tell you to gat a FASST or Spektrum module as you are correct it wont help the latency.

You need to weigh what you want in a radio and decided. I know it's a tuff choice but you need to get what you want and like.

Myself I am using a DX7 for now but I will sell it the minute the FASST module is here for my 14mz. I felt the loss in resolution when I went to the DX7 from my 14mz with G3 2048 resolution. The 14mz 2048 did feel better to me.

However I DID feel an improvement on my Trex450 going from 1024 PCM to the DX7 as I went from a 65 latency on 1024 PCM (even the 14mz is that slow on 1024) to a 25 with the DX7 and a higher resolution.

So, you need to decide if latency and resolution is worth getting a new radio. I suggest if you have a chance to fly a DX7 and see if you feel it.

Bob

[heliboy88]

Hi Bob,

Thank you very much for the detailed explanation and advice. Since i'm still new to this 'addiction', i don't think i'll really feel the latency between the two. But another thing i'm worried about is the 'poor' eccpm performance of the 9C as said by others. And just want to know how poor is it comparing to other radio or in what way is it 'poor'.
BTW, sorry for being off topic, just can't get answers in other places.

Best regards,
Rich

[Skiddz]

I own both the 9C and a DX7. The feel of the 9C in my hands is much more "substantial" and it's pretty well balanced when hanging off my neck strap.

The DX7 just feels "cheap" - kinda like a RealFlight Interlink Controller on steroids - and is very unbalanced on the neck strap

Programming wise, the DX7 has a shallower learning curve than the 9C, but nowhere near the capability of the 9C.

Right now I only have one heli on the DX7 (My 450 SEV2) because I don't care for the feel of the Tx.

I can't really tell the difference between the control response of the two radios, but I'm far from being experienced enough to really do so.

I'm anxiously awaiting the new 12ch FASST rig from Futaba because I like the 2.4GHz security and if it "feels" like the 9C, it'll be that much better. Am I going to buy a FASST module for it? Nope. Gonna hold out for the 12TG 2.4GHz version - for now. :)

If you can get your paws on a DX7 and try it, by all means, do so. It's not a bad little radio, I just prefer the feel and function of my 9C.

[heliboy88]

Hi Skiddz,

Thanks a lot for the heads up. I really love the feel and easy programming of the 9C. But what's bothering me is that i've heard about the 'poor' eccpm performance of the 9C. And i really want to know how 'poor' and in what way is the said 'poor' performance.

Best regards,
Rich

[kgfly]

Danal - I think the buzzing is power-supply and duty-cycle related but comes primarily from the voltage regulator. My DX6 use to have the same buzz but once I replaced it with the DimensionEngineering switched-mode regulator it never buzzed again (and I doubled my battery life :) ). I have heard others have the same outcome when making the same mod to their DX7.

heliboy88 - Details about the attributes of the 9c eCCPM mixing issues can be found (with some digging) in this thread: http://www.runryder.com/helicopter/t172571p1

Contributing factors are:
* Slow mixing calculation of ~20ms (compare PPM eCCPM to PPM Normal)
* Updates get spread across two frames contributing to large inter-channel skew
* Software limits the max slew rate which means servo performance will never exceed 0.20s no matter how fast the servo is inherently

If you like your 9c but don't want to spend too much on a 2.4GHz upgrade I would recommend XPS ( http://www.xtremepowersystems.net ). It is much cheaper than either FASST or Spektrum ($189 with 8ch Rx) with cheaper Rx and IMO better and has more potential.

Skiddz - Unless you have seen some new information the new 12FG is not an integrated 2.4GHz radio but is a modular Tx for which you can buy a FASST module. If you do have a link to info about an integrated 12ch FASST Tx I would be very interested to learn about it.

[heliboy88]

Hi kgfly,

Thanks again for your infos. I'll go thru the link you gave me. Actually, it's just hard for me to decide whether to get a dedicated 2.4G radio or just get a module for the 9C. And if i get the DX7, is it the right time now(with the version 1.2 AR6100)? Cus i've heard a lot about the DX7 eg. low voltage reboot and/or screen shut down(or upside down). I also know that the dealer is more than willing to change or fix the unit if there're problems, but as said i'm in the Philippines and the sending back is already a problem, not mentioning another payment of taxes when it is mailed back to me.
That's why i'm really stuck to what is the best to do. Any idea?

Best regards,
Rich

[kgfly]

Rich - There is no right and wrong, it is all about personal preferences. What suits some folk or seems important to them does not suit or is not important to others.

I am personally a huge fan of the advantages of the new 2.4GHz spread spectrum R/C technology and wouldn't spend money on anything else these days. If I was buying a brand new radio today it would be a DX7. If I needed (or just wanted :) ) a fancy 9ch radio I would wait for the new JR X9303/9Xv3. If I had a 9C and was happy with it then I would get the XPS module and Rx.

All of the 2.4GHz Rx take longer to reboot/reacquire connection than existing FM Rx. This means you have to ensure that the RX power supply on every model is appropriately sized/rated/designed to ensure it never overloads or overheats. Just because it worked on FM doesn't mean it is actually OK, it may be having short brownouts that seem like glitches with an FM RX but will likely cause a reboot and crash on 2.4GHz. Luckily, providing a robust Rx power supply is not hard.

You must ensure any 6100 you use has the v1.2 firmware, they seem fine with this upgrade but are unsafe without it.

So, your cheapest way forward is to keep the 9C and buy an XPS solution for it. Then go fly your new CCPM heli and see how it feels. If you don't have a problem with the handling then all is sweet. If you do, then I am sure you could sell the system easily and buy a DX7 or X9303 to replace it.

[heliboy88]

Hi kgfly,

Thanks very very much for being so helpful and supportive all the time. :noteworthy
I'm actually selling my 9C and just let the destiny decide on what i should get. :wink: If someone will get my 9C then i'll definitely go for the dedicated 2.4G radio(most probably a DX7).

Best regards,
Rich

[kgfly]

The DX7...is very unbalanced on the neck strap
Not with one of these: http://www.spektrumrc.com/Products/ProductGallery.aspx?ProdID=SPM6703 :wink: