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HELP! Spektrum DX7 radio failure?

Old 07-27-2007, 09:35 PM
  #101  
Lieutenant Loughead
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Default Spektrum's Response...

Thank you for your recent e-mail. I'm sorry to hear about the lack of
service you feel you received. I would be more than happy to tell you
what is going on with your system if you could give me more details
behind the failures of the radio. The most common issue with failures
however in electric planes is the BEC overheating and failing. Keep in
mind a voltage drop below 3.5v on a Spektrum receiver will result in a
reboot of the system and it will need to rebind, just like when you
first turn on the radio and receiver. I'm not saying this is the
problem your are experiencing but more than likely it is. Again if you
could provide me with more information on what the setup of the plane is
like what ESC, what battery, what servos, motor, prop, and amp draw off
of the ESC.

I hope you find this information useful. If you have any further
questions, please reply to this e-mail give us a call at 1-877-504-0233.
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Old 07-27-2007, 09:36 PM
  #102  
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Default My response to Spektrum...

Daniel -- I have already supplied this information to Larry Ince at Spektrum. He has my transmitter and five receivers for repair.

The problem was not a BEC issue -- talk to him about this.

To be honest, your response is indicitave of the problem I am experienceing with Spektrum. You guys seem to have the same canned response, every time I communicate with you, and I find it VERY frustrating; the problem is NOT the BEC (three different BECs on three differernt airplanes, with three different battery packs, and three different AR6100 receivers) -- the only common denominator here is the SPEKTRUM TRANSMITTER!

The quick answer here is to replace my DX7 with a NEW, "factory fresh" unit -- the one you sold me is a lemon!

When you send my DX7 and five AR6100's back to me, I plan to install an in-flight meter, to measure minimum volts, and maximum amps to the receiver. The next time I have a catastrophic radio failure (I have had THREE so far), I can tell you EXACTLY what the battery voltage and amp draw was.

However, I believe Spektrum should be doing this testing, instead of me. I have already lost three airplanes to your product; I am not eager to lose a fourth!

sincerely,
(name witheld)
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Old 07-27-2007, 10:33 PM
  #103  
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Originally Posted by paranoia View Post
\So I concluded that the Tx was not pumping out the power needed, even when the display said 10.1.

Ah well the issue you had was probably not the firmware glitch then - it has very specific symptoms. If the pack has voltage under load (switched on) there is no question of whether it can supply amps - if it could not do so the voltage would sag. If the volts are present under load that's all it takes. I wonder if it was an intermittent connection or something - the meter was reading samples or averaging or something and didn't care, but the radio wasn't getting clean DC?

I have had range check issues with the AR6100 and the TX oriented in such a way that they had their antennae pretty much co-linear. Tilting the TX or walking a few steps either direction fixed it, and technically the range check passed since I was a few hundred feet away before I lost link.

Other than getting bit twice by the 6100 bug (once on the ground, once in the air) my DX7 has been flawless.


Originally Posted by Lieutenant Loughead View Post
Keep in
mind a voltage drop below 3.5v on a Spektrum receiver will result in a
reboot of the system and it will need to rebind, just like when you
first turn on the radio and receiver.
This guy is a tool. First he hasn't done any research on your history (it should be in the issues database with your ID number) and second this statement is crap - they reboot and relink they most assuredly do not "rebind" spontaneously in the air.
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Old 07-27-2007, 11:41 PM
  #104  
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mmmmm...... when i requested a battery replacment under warrenty i got the same try of run around. They just said it's normal, and the pack was okay, mmm... fun that everything work correctly after i got rid of it.....
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Old 07-27-2007, 11:46 PM
  #105  
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Originally Posted by paranoia View Post
mmmmm...... when i requested a battery replacment under warrenty i got the same try of run around. They just said it's normal, and the pack was okay, mmm... fun that everything work correctly after i got rid of it.....
Well, current equals voltage divided by resistance is pretty definitive. If the voltage is OK the current will flow, if the source cannot supply the current the voltage has to sag. I don't make the rules.

I'm not saying the battery wasn't bad, I'm saying that "it had good voltage but no current" isn't how it was bad if the voltage was in fact correct under the load.
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Old 07-27-2007, 11:51 PM
  #106  
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unclebob

as i said when the Tx was on i could see the voltage dropping before my eyes, about .1V every min or so..... even with the pack unplug it would be lossing volts/power
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Old 07-28-2007, 12:06 AM
  #107  
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Let me give an example. If you had a device with an old fashioned meter on it and the meter read 12 volts before you turned on the device and then, when you switched the device on the meter instantly dropped to 7 volts, that is the voltage sagging under a load. This is the case where "the battery can't supply the current", but since the DX7 meter only works while the TX is on a guy would have to use an external meter to observe this.

This is precisely why a good garage will load test automotive batteries.

Dropping .1 volts per minute might be excessive (I've never watched mine, I have to watch the plane) but it's not an example of sag under load, it sounds like discharge, maybe as you surmised partially internal and partially running the TX. As long as there is adequate voltage to run the TX the trend of the supply shouldn't matter, however, and I routinely run mine around 10.2 or more volts. I just realized it's a nominal 9.6 volt pack recently and so I figure I'm being overly conservative - in the past I just went by the little "gas gauge" to see if it was fullish or not.

In any case it's nice yours is fixed.
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Old 07-28-2007, 12:30 AM
  #108  
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I am intrigued by this issue of the TX battery being bad. I have a feeling that mine might be.

I notice that my battery will not hold a charge very long, whether it is being used or just sittin there on its own. I charge it all the way up to 11 whatever volts and then by the time I am done with 2 flights on an airplane (like 30 minutes or so) its getting close to 10 or less volts. I have many many glitching issues with my 72mhz eq and I wonder if this is the culprit! Might save me $300 by not having to go buy a spectrum system.
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Old 07-28-2007, 12:49 AM
  #109  
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Not to start judgement on the xmtr packs, but is 'McNair' a name brand?

All it has is 8 AA batteries. I've been talking to Jam @ maxamps about lipo replacement for the DX7. Have not come to any major conclusion that it will work.
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Old 07-28-2007, 02:53 AM
  #110  
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United Hobbies sells a pack they report using in the DX7 systems THEY use themselves. I have one but I'm gonna look into a balancer before I install it.
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Old 07-28-2007, 04:35 AM
  #111  
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yep my pack was a McNair brand.....
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Old 07-28-2007, 05:12 AM
  #112  
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I don't know how common the McNair name is but my DX-7 stock battery and the upgrade battery I bought for my DX-6 are both McNair. I have had no problem with either one. They will hold a charge that will allow me to fly for at least 3 weeks, maybe longer.

My 600 NiCads in other transmitters won't come close.
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Old 07-28-2007, 05:26 AM
  #113  
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Originally Posted by Lip84 View Post
I am intrigued by this issue of the TX battery being bad. I have a feeling that mine might be.

I notice that my battery will not hold a charge very long, whether it is being used or just sittin there on its own. I charge it all the way up to 11 whatever volts and then by the time I am done with 2 flights on an airplane (like 30 minutes or so) its getting close to 10 or less volts. I have many many glitching issues with my 72mhz eq and I wonder if this is the culprit! Might save me $300 by not having to go buy a spectrum system.
This should not be a problem. It is an 8-cell pack, so the nominal voltage is 9.6V. When fully charged, you will get in excess of 1.4V per cell (hence 11.2V or so) but the voltage will quickly drop to around 1.2V per cell (9.6V). It will then remain fairly steady around 9.6V until the battery is close to fully discharged, when again the voltage will drop rapidly. This is the standard discharge curve for NIMH cells. See some examples in the attached image.
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Old 07-28-2007, 07:38 AM
  #114  
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I am not entirely clear on this. I have the standard 600mAh TX pack in my Hitec Flash 4X and when I charge it up it will top out at around 12 volts. When I use it the voltage drops and it will sound an alarm at around 9.4 volts. (Forgive my voltages, these are from memory).

It also does not hold a charge very long but then again I have been using this battery in the TX since I got it around 6 or 7 years ago. It also spent a 3-4 year period in there just sitting in a box unused. I believe that it was mostly discharged when it started sitting.
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Old 08-01-2007, 06:59 PM
  #115  
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Originally Posted by Rabbitcreekok View Post
I don't know how common the McNair name is but my DX-7 stock battery and the upgrade battery I bought for my DX-6 are both McNair. I have had no problem with either one. They will hold a charge that will allow me to fly for at least 3 weeks, maybe longer.

My 600 NiCads in other transmitters won't come close.


yep, i've only had my new home made pack for 2months and only charged it once it's 2500mAh
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Old 08-01-2007, 07:02 PM
  #116  
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PING!

Hey Loughead...you hear anything from the folks that have your TX?

I think i speak for most when i say we are champing at the bit to hear more...its like a bad porn movie or a train wreck..you cant help but watch as it burns a scarred image into your memory...
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Old 08-01-2007, 08:50 PM
  #117  
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LOL -- I called the tech yesterday. He said he asked someone to fly with my transmitter -- two 15-minute flights. However, the pilot only flew ONE 15-minute flight (with excellent results, exactly as I have seen).

The tech said he would ask the pilot to fly TWO 15-minute flights this morning. I have not heard back from him.

The weather has been AWESOME here lately -- and Spektrum has my transmitter...

Here are some things of note, which the Spektrum tech said during our last discussion:
1) He does not believe the story about the bad transmitter battery -- he said he would know about it, if that were a common problem with Spektrum transmitters.

2) He has seen issues with large, metal surfaces -- like metal picnic tables, or the bed of a pickup truck. Yet, this does not explain a failure in the air.

3) He said fiberglass, covering, and paint will have no effect on the reception of the radio signal. He went on to say that one user has a Spektrum receiver inside a fuselage made entirely of ALUMINUM -- with no issues.

4) He said the good people at Spektrum are very busy -- they can't meet demand for new units. (Not sure if that ment Tx, or Rx, or both...
I think that's about it... I've built a new airplane since mailing my transmitter to Spektrum -- I wonder if I can build TWO airplanes before I get my receiver back?
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Old 08-01-2007, 09:00 PM
  #118  
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Oh -- in the meantime, I took the Spektrum tech's response, and modified a servo extension cable to use with my WattsUp meter -- the idea being to measure the minimum volts and maximum amps between the BEC and receiver.

I have tested my Electron 6 receiver with the components of the crashed P-38 -- both with the servos at idle, and with the servos under a load. I have tested with a 2s, 3s, and 4s LiPo...

The "worst case" was with the 4s LiPo (what I was using when the P-38 crashed) -- 4.94 volts minimum, and 0.31 amps peak.

Now, if the numbers are different with the Spektrum receiver, then the problem is STILL on Spektrum's end. However, I can not test with the Spektrum equipment, until I receive my Spektrum Tx and Rx (x5) back from tech support...
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Old 08-01-2007, 09:27 PM
  #119  
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hmm..the saga continues. This is a most purplexing ordeal.
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Old 08-06-2007, 07:32 PM
  #120  
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Ya know....I was all fired up to buy a spektrum DX7 before I saw this thread. I am not terribly worried about getting one and finding out it sux. But I do worry about it...thats a lot of money to throw away on a product that might not work right. I am also less than thrilled with their support staff and Lougheads experience....

What to do what to do....I have lost several airplanes to interference and I need a solution!! :< I cant lose my new baby.

Lip84
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Old 08-06-2007, 07:36 PM
  #121  
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The odds are in your favor - this thread is what I would call a horror story. Spektrum would, if smart, replace this unit and subject the returned one to extensive testing before selling it as a refurb or something.

I and two of my brothers all have DX7s - zero issues, great radio. My brother got a DX7 with micro servos and AR6100 for $280.
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Old 08-07-2007, 07:16 PM
  #122  
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Well, another week has passed... I have been without my Spektrum DX7 for three weeks today...

Today, I received a phone call from the Spektrum technician... He said they tested everything, and it's all okay. They performed two 10-minute flights with my Tx and Rx, and an electronics system setup similar to mine -- and it performed flawlessly. As a result, the tech wanted to send the radio back to me with "no problem found".

At that point, he suggested we swap out all the receivers (five of them). I asked if I could "upgrade" to the new AR7000 (four antennas) -- he said they were not shipping yet...

I told him I didn't think the receivers were the problem, since I had failures on three different receivers -- it had to be the transmitter...

He said he would look one last place -- someplace he hasn't looked in the last three weeks he's had my transmitter.

Guess what? 20 minutes later, I receive another phone call from the Spektrum tech. He says he found a crease in the coax cable which leads from the circuit board to the antenna. He said it could cause a problem -- "anything can cause a problem with 2.4 gigahertz."

So -- now my radio is on it's way back to me... I will test with some flat foamies I've built, before I trust this radio to my more valuable aircraft...
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Old 08-07-2007, 07:23 PM
  #123  
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Originally Posted by Lieutenant Loughead View Post
Well, another week has passed... I have been without my Spektrum DX7 for three weeks today...

Today, I received a phone call from the Spektrum technician... He said they tested everything, and it's all okay. They performed two 10-minute flights with my Tx and Rx, and an electronics system setup similar to mine -- and it performed flawlessly. As a result, the tech wanted to send the radio back to me with "no problem found".

At that point, he suggested we swap out all the receivers (five of them). I asked if I could "upgrade" to the new AR7000 (four antennas) -- he said they were not shipping yet...

I told him I didn't think the receivers were the problem, since I had failures on three different receivers -- it had to be the transmitter...

He said he would look one last place -- someplace he hasn't looked in the last three weeks he's had my transmitter.

Guess what? 20 minutes later, I receive another phone call from the Spektrum tech. He says he found a crease in the coax cable which leads from the circuit board to the antenna. He said it could cause a problem -- "anything can cause a problem with 2.4 gigahertz."

So -- now my radio is on it's way back to me... I will test with some flat foamies I've built, before I trust this radio to my more valuable aircraft...

You have got to be kidding me. (Jaw dropped and dumbfounded look on face)

A crease in the coax is the root cause? Do you believe him? This story makes me want another mfg. of 2.4 ghz systems to come forward fast in the market place.
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Old 08-07-2007, 07:27 PM
  #124  
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First tier Tech Support is the armpit of any business I've ever worked in. Sigh. Hope for the best, plan fo rthe worst.
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Old 08-07-2007, 07:28 PM
  #125  
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...??

wow....spektrum has dropped the ball...I am still very very discouraged to buy a spektrum.

I had done research on all the 2.4 ghz radio systems and I think Im going to go back and take another look at the Futaba Faast stuff. I was nervous about the channel hopping but it looked like the best alternative to spektrum other than the XPS. Only problem with XPS is that you need to have a several hundred dollar remote to buy a several hundred dollar module for...

At least we know we can trust futaba...right?

P.S. my condolences on your loss Loughead...i feel for you.
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