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HELP! Spektrum DX7 radio failure?

Old 04-05-2011, 05:51 PM
  #1326  
kyleservicetech
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Originally Posted by Saddlebum View Post
I fail to see the need to screw around with the stock battery, anyway. My Dx7 can run all day long (and I mean 8 hours of flying) without a recharge. Who needs more than that?

...The Bum

Agreed:
Nothing wrong with a good quality Nih battery for your transmitter. They work, and have a long history of working very well in this type of application. Charging them is simple, just connect a simple wall wart charger to them for 15 hours or so. And their failure mode, after long use is generally lower ampere hour capacity, or zero volts on a cell. (Your transmitter will still work on 7 cells) This is easily spotted before flying or while flying your model.

An A123 type of battery with three cells would work very well in a 9 Volt transmitter. Problem with them is, their discharge voltage is very flat, with little voltage difference between 90% of charge and 10% of charge. From the two A123 cells I've had fail, their failure mode was open circuit, meaning zero output from the battery. (This was under 30 Amp loads, far different from transmitter loads) And, lithium technology batteries such as Lipos and A123 cells must be balanced on a regular basis (which is why my two A123 cells failed)

So, when the low voltage alarm goes off on a transmitter equipped with A123 type cells, you'd better be just landing your model
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Old 04-05-2011, 06:00 PM
  #1327  
groundrushesup
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has anyone used one of these 8 cell holders they sell at Radio shack with LSD nimh's?



http://www.radioshack.com/product/in...ductId=2062251

I am looking specifically at fitment (if the plastic shell fits in the battery bay).

TIA,
GRU
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Old 04-05-2011, 06:12 PM
  #1328  
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Originally Posted by Saddlebum View Post
I fail to see the need to screw around with the stock battery, anyway. My Dx7 can run all day long (and I mean 8 hours of flying) without a recharge. Who needs more than that?

...The Bum
If that works for you then great, but it does not work for me. Even when the DX7 was brand new and the battery pack was too, it didn't last through a whole day of flying unless I was careful to turn it off as much as possible. With the a123 style battery pack, it will literally run all day - and it will hold a charge for weeks, so there's none of that self-discharging issue. AND, I can charge it out at the field on my regular charger, very quickly if needed. I can charge the stock packs too, but it takes a long time and is never worthwhile to start that out at the field because it will never be done in time for me to get a flight in.
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Old 04-05-2011, 07:27 PM
  #1329  
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"(Yes exactly - plugging a Lipo will cause a number of problems. You need to use a 3-cell LiFePO, which stabilizes at about 10V and runs for weeks like that, and doesn't over-power the DX7.)"
What is a good example(where to go website) to view one of these batteries.
Also, yes my warranty is voided but if my TX fails, I'll buy another DX7

John
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Old 04-05-2011, 07:49 PM
  #1330  
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Originally Posted by Saddlebum View Post
I fail to see the need to screw around with the stock battery, anyway. My Dx7 can run all day long (and I mean 8 hours of flying) without a recharge. Who needs more than that?

...The Bum

8 hours of actual flying or 8 hours at the field? My dx7 on the stock pack would barely make it through a day of flying before making me nervous
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Old 04-05-2011, 08:09 PM
  #1331  
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Originally Posted by celticflyer View Post
"(Yes exactly - plugging a Lipo will cause a number of problems. You need to use a 3-cell LiFePO, which stabilizes at about 10V and runs for weeks like that, and doesn't over-power the DX7.)"
What is a good example(where to go website) to view one of these batteries.
Also, yes my warranty is voided but if my TX fails, I'll buy another DX7

John
http://www.hyperion.hk/dn/fg3radio/default.htm
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Old 04-06-2011, 12:11 AM
  #1332  
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At the risk of sounding like a broken record. Eneloop-click, Eneloop-click, Eneloop
Pete
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Old 04-06-2011, 02:52 AM
  #1333  
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Originally Posted by groundrushesup View Post
has anyone used one of these 8 cell holders they sell at Radio shack with LSD nimh's?



http://www.radioshack.com/product/in...ductId=2062251

I am looking specifically at fitment (if the plastic shell fits in the battery bay).

TIA,
GRU
IMHO, this type of battery holder might be OK if you're flying a very inexpensive model. But when going to models over perhaps $100 or so, the reliability of this type of battery holder leaves a lot to be desired. Over a period of time that plastic starts to deform, changing contact pressure on the cells. And those coil springs are just stuck in place over a rivet in plastic. Again, that coil spring can loose contact pressure over a period of time.

Welded and soldered connections that are used in our Nih powered radios are the way to go.
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Old 04-07-2011, 10:46 PM
  #1334  
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I've owned my DX7 for maybe a year and a half only coupled to a micro heli I have. I have just decided to swap over all of my park flyers to Spektrum and just lost my first plane last weekend due to a lockup in a newly installed 6110e. I cannot verify exactly if this was a lockout but what I experienced was a loss of motor control about 30 feet in front of me about 5 min into the flight. It was very quick and I had pulled the throttle stick down and then up again to rearm the esc and then it appeared to start back up. I had full control for another 30 seconds and kept the plane as level as I could thinking that maybe there was a lockup of a servo that caused a voltage drop to the rx and upon bringing the plane around it just stopped dead. I had zero control and at about 30 feet up, it nosed down and piled itself into the ground like flat foam wing would without a glide ratio. Luckily I only lost the airframe but I am stumped. Horizon wants to send it back for inspection. I just have this feeling its going to pass with flying colors. These lockouts are like little gremlins that take the joy out of flying because you start to doubt your equipment.

To sum up.
I have ran 2 bench tests with all the original equipment from that model and trying to replicate the lockup but adding a little pressure to the servos, working all 3 at the same time at full throttle and as I put a volt meter on the 6110e, it reads a continuous 5.5 volts.

With a prop attached and at full power on a stationary vice, I tried to heat up the esc to see if something would trigger there as well and even walked down the street and behind my house. Still that rx light is solid and will not repeat a brownout of any kind.

I'm going to give this UBEC thing a try and put it in a new plane, but if I encounter another one of these lockouts, I think I'm done with Spektrum and will go back to Airtronics where I only doubted my skils.

Equipment in question was:
12 oz foam 3d Bipe
Axi 2212/34
CC Phoenix 10
Thunder Power 1320 15c 3S lipo
3 Hitec 55s
Spektrum 6110e

Last edited by evlwevl; 04-07-2011 at 11:02 PM.
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Old 04-08-2011, 04:08 AM
  #1335  
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Yup... classic BEC failure. VERY hard to replicate.

Do your range checks, and when you find the edge of the range, have a friend turn the plane while you wiggle the sticks and see if you can reduce the range by putting the plane in a certain orientation. With the small receivers, it's remotely possible to block the signal with a battery or a large motor or some carbon fiber.

I've used Spektrum for years, and I've never had a problem I couldn't explain except once. Problems with the radio system include one case of antenna blockage which was my fault, and a few cases of rather obvious BEC failure, and one completely mysterious failure which caused temporary loss of control (still working on that one). That is over the course of 4 years, almost 5 years of flying planes and helis. I keep a lot of safety margin in my power setups. The Phoenix ESCs are good, but when using 3S batteries it is recommended to use a separate BEC. I think this is stated in the manual...
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Old 04-08-2011, 05:06 AM
  #1336  
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what would work best? All of my Ar6110e are in park flyers that run on 3s

I've read some people use these, but it states not for aircraft use and doesnt mention DSM2
http://spektrumrc.com/Products/Defau...ProdID=SPM1600

and then there is this
http://www.castlecreations.com/products/ccbec.html

Which apparently works in EP planes. I use these in my surface vehicles now to keep my ESCs from heating up when using 3S lipo
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Old 04-08-2011, 06:05 AM
  #1337  
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Originally Posted by evlwevl View Post
what would work best? All of my Ar6110e are in park flyers that run on 3s

I've read some people use these, but it states not for aircraft use and doesnt mention DSM2
http://spektrumrc.com/Products/Defau...ProdID=SPM1600

and then there is this
http://www.castlecreations.com/products/ccbec.html

Which apparently works in EP planes. I use these in my surface vehicles now to keep my ESCs from heating up when using 3S lipo
This might be to heavy for a park flyer, but take a look at Castle Creations 50 Amp Lite ESC with an included uBEC. Total weight with wires is 1.7 ounces, and about an ounce less without wires.

http://www.castlecreations.com/produ...oenix_ice.html
The uBEC is a switching type of Battery Elimination Circuit which should take care of any brownout issues.

I've check all 6 of my Spektrum AR7000 receivers, they all work down to 3.15 Volts DC. Below that voltage, the receivers microcontroller reboots. I've got three of the CC uBEC 10 Amp units in my Kilowatt powered models, they've all been flawless over the past three years.

Note that the latest software in the various Spektrum receivers will flash the receivers LED if the unit got hit by a battery brownout during a flight.
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Old 04-08-2011, 04:44 PM
  #1338  
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Originally Posted by evlwevl View Post
what would work best? All of my Ar6110e are in park flyers that run on 3s

I've read some people use these, but it states not for aircraft use and doesnt mention DSM2
http://spektrumrc.com/Products/Defau...ProdID=SPM1600

and then there is this
http://www.castlecreations.com/products/ccbec.html

Which apparently works in EP planes. I use these in my surface vehicles now to keep my ESCs from heating up when using 3S lipo
On tiny park flyers, the best bet is to use an ESC with a more than sufficient BEC built in, AND a large safety margin for the motor. For example, my Slow Stick runs a Thunderbird 18 - same BEC as your Phoenix. However, since it only has two servos and the motor only pulls 9 amps, and the ESC sits in the open air right behind the prop, I don't have any problems, even with the lights running (about 1-amp worth of lights).

However, when you're running 9 amps on a Phoenix 10, plus running the BEC on 3S lipos, plus it's stuffed inside a plane somewhere with less airflow, then you've just pushed over the line a little bit - which is why it works most of the time and fails rarely for you.

Running a 2S setup will help, as would moving the ESC into the airflow a little better if it's not, upgrading to a better ESC like the T-bird 18 (it is better able to evacuate the heat from the motor driver), or installing an external BEC. I use the Castle BEC, but I think the uBEC is a little lighter weight.
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Old 04-08-2011, 04:46 PM
  #1339  
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Originally Posted by kyleservicetech View Post
This might be to heavy for a park flyer, but take a look at Castle Creations 50 Amp Lite ESC with an included uBEC.
uBEC is a brand name, not the name of the device. The ICE ESCs are good but overkill for little stuff. I've seen them on Trex 250s and it's just ridiculous. It has a switching BEC, which is better than the linear BECs usually built in to the ESCs. The external BECs are all the switching type as far as I know.
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Old 04-08-2011, 05:22 PM
  #1340  
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Originally Posted by jasmine2501 View Post
uBEC is a brand name, not the name of the device.
Brand name? Didn't know that, but did find that several different suppliers use the term uBEC as a reference to a switching power supply type of BEC.

Any Wattflyers have an input on this
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Old 04-08-2011, 06:35 PM
  #1341  
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Originally Posted by jasmine2501 View Post
uBEC is a brand name, not the name of the device.
Quoted for clarity. My understanding is the a BEC and a uBEC are the same thing - though the way that the functionality is provided is different. I welcome every opportunity to learn more if I am in error here.

A 'standard' BEC uses a linear voltage regulator, which wastes as heat the difference between the battery voltage and the BEC output MULTIPLIED by the current supplied by the BEC.

You can draw more current for radio and servos from a 2S battery than you can with a 3S battery.
As an example, consider a 3A BEC providing 5v 3A, running on both a 2S setup and a 3S setup. When running on 2S, the regulator has to dissipate as heat (7.4v-5v)*3A = 7.2 Watts.
When the same load is provided but powered by a 3S battery, the BEC is now required to dissipate (11.1v-5v)*3A = 18.3 Watts.
By adding 50% to the input voltage, we add 150% to the thermal load of the regulator. This is BAAD.


Enter the uBEC, or Ultimate Battery Eliminator Circuit. While still providing a 5(or 6v) source from your onboard battery, it no longer wastes the extra energy as heat - instead switching on and off very rapidly to ensure that a (small) power reserve - a capacitor, has it's voltage maintained. The higher the required power from the uBEC, the higher the switching rate.

Google switch-mode power supply for more info, specifically "Buck Converters". Far more compact, efficient and powerful than linear voltage regs.


S.
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Old 04-08-2011, 08:17 PM
  #1342  
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Originally Posted by Simon View Post

Enter the uBEC, or Ultimate Battery Eliminator Circuit. While still providing a 5(or 6v) source from your onboard battery, it no longer wastes the extra energy as heat - instead switching on and off very rapidly to ensure that a (small) power reserve - a capacitor, has it's voltage maintained. The higher the required power from the uBEC, the higher the switching rate.


S.
These switching power supply voltage regulators or battery eliminator circuits have gotten a lot simpler with the introduction of single chip integrated circuits designed specifically for use as a uBEC.

Take a look at the datasheet for:
http://search.digikey.com/scripts/Dk...LM2596T-5.0-ND

This chip sells for about $5, and only needs four other components to build up a fixed 5 Volt 3 Amp DC supply, with the input voltage range from 7 volts DC to 25 or 30 Volts DC. But, by the time you buy this chip, the required circuit board, and the four other parts, you've spent more than a brand new Castle Creations 10 Amp uBEC! (The parts costs go way down when a manufacturer buys parts by the thousands rather than one at a time.)
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Old 04-09-2011, 11:00 PM
  #1343  
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Not until recently. The device is just called a BEC. The u was added by somebody for no reason - it doesn't mean switching (although, it is possible that it has fallen into use that way - very inaccurate if it has). The Castle BECs are all switching type, and they are careful to say so. Make sure what you're getting is what you want, because the u doesn't mean anything as far as I know. There used to be an actual product called "The uBEC" but I don't see it out there any more. In the case of that product, I believe the u was chosen to mean "micro".

Look at the language Castle uses - it is 100% consistent. If the u meant anything, they would use it. The u is not in any of the product names or literature. I do not know why the bargain brands are using it - perhaps they also mean micro.
http://www.castlecreations.com/products/ccbec.html
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Old 04-09-2011, 11:18 PM
  #1344  
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U stands for ultimate. Not sure it started with this brand but...

http://www.rcgroups.com/forums/showthread.php?t=141456
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Old 04-10-2011, 02:05 AM
  #1345  
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Originally Posted by jasmine2501 View Post
Not until recently. The device is just called a BEC. The u was added by somebody for no reason - it doesn't mean switching (although, it is possible that it has fallen into use that way - very inaccurate if it has). The Castle BECs are all switching type, and they are careful to say so. Make sure what you're getting is what you want, because the u doesn't mean anything as far as I know. There used to be an actual product called "The uBEC" but I don't see it out there any more. In the case of that product, I believe the u was chosen to mean "micro".

Look at the language Castle uses - it is 100% consistent. If the u meant anything, they would use it. The u is not in any of the product names or literature. I do not know why the bargain brands are using it - perhaps they also mean micro.
http://www.castlecreations.com/products/ccbec.html
Learned something today!
Maybe we should start something new, and call these switching BEC's a SwBEC
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Old 04-12-2011, 04:22 AM
  #1346  
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I would be down with sBEC

Sorry to be such a stickler, I just wonder about these things sometimes. It's the danger of the world economy I guess. Do you know how long it was before I realized 'naro' wasn't just 'nano' in Engrish, that they named it that on purpose?
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Old 04-12-2011, 05:24 AM
  #1347  
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Originally Posted by jasmine2501 View Post
I would be down with sBEC

Sorry to be such a stickler, I just wonder about these things sometimes. It's the danger of the world economy I guess. Do you know how long it was before I realized 'naro' wasn't just 'nano' in Engrish, that they named it that on purpose?
LOL
Before retiring I worked for a company that manufactured high voltage circuit breakers that used high voltage contacts submersed in oil for insulation. That transformer oil was a problem if anyone shot holes in the tank, what with the resulting oil spills, loss of oil insulation and resulting fire.

After millions of dollars in design work, the Engineers came up with the first vacuum contact, that could handle 800 Amps at 15,000 volts, with the ability to interrupt 12,000 Amps on a fault. So, the Engineers designed a No Oil, Vacuum circuit breaker, and trade marked it "NOVA".

Problem is, in Spanish, NOVA means something like, "Doesn't Run"!
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Old 04-13-2011, 05:40 AM
  #1348  
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Yeah that's an old Chevy joke.
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Old 04-13-2011, 06:21 AM
  #1349  
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Originally Posted by jasmine2501 View Post
Yeah that's an old Chevy joke.
LOL
If I remember right, we had problems with trademark names with Chevy and CPS NOVA circuit breakers.
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Old 04-14-2011, 03:25 AM
  #1350  
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NOVA = No Va = No Go
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