skubacb

RE SPM1600. This is not a NEW fix. If you take a look this first came out for Spektrum receivers in RC cars. So I would have thought Spektrum would have improved their DSM2 receivers so this would not be needed. I normally run 6 volt batteries with either 1650 or 2700 mah. Battery voltages were checked and my total loss of control was clearly NOT due to my batteries being low. The the largest A/C was 60 sized and was running 6 servos.

rino

My Feedback: (121)

Craig,

Did you send your stuff in for HH to look at. I was wondering if they even speculated on the cause. I remember you posting a while back and thinking that you had the appropriate battery for your system. Could you have gotten a bum rx?

NJRCFLYER2

My Feedback: (42)

This so-called voltage protector is nothing more than a small electrolytic capacitor. All that it does is help smooth out very brief dips in voltage under load. It can not and will not compensate for a battery and/or regulator system that isn't capable of providing a sustained voltage output that is at or above what the Spektrum receiver requires. This is a kludgy patchwork response for a problem that has to be addressed in an entirely different way. I hate to be so blunt, because I really think highly of Horizon and their product support over the years. This just isn't the way to go. BTW, I have a DX7, it's working great, but don't expect this capacitor add-on to solve your problems in a reliable way. If you can create a condition where it appears to solve it, then you can also create a slightly worse condition that it won't cover up. It only takes a higher current spike, a longer current spike or a combination of both to bring down the voltage far enough and for long enough that the capacitor will have discharged to a point that it can't maintain a sufficient voltage to mask the problem.

At_Your_Six

NJRCFLYER2

I agree with you 100%! That capacitor is a poor bandaid to this problem. I am running 6.0 volts setups from now on and no more digital servos. Spektrum and HH are getting a black eye on this one for sure!

Six

aresti1963

The solution to this problem is to use an rx pack that will deliver the higher amperage needed without dropping the voltage level. I had some packs made up by a UK based company called 'component shop' (the guy, Ian, really knows his cells) and they are capable of delivering 15amps +, without the voltage taking a big trip south. Using packs made from AA cells will always be a problem as far as voltage drop is concerned, due to their inherent, high internal resistance. Increasing the capacity will not allow the voltage to stay higher. Under low amp loads, they will work, under high amp loads they will drop their voltage VERY quickly.
The packs I use are 6v 1400mah and are fast chargeable at a 1c rate, meaning, I can recharge at the field every 2-3 flights.

ALSO, invest in an onboard voltage monitor, placed where you can easily see it at switch on before every flight. The packs I am using are only about a half ounce heavier than the AA packs they replaced. In all honesty, most .60 size aircraft could handle the weight of even sub 'c' size packs without any problem at all. The majority of these cells will provide the amps without the voltage drop.

Just my tuppence worth, but it works faultlessly for me.

BTW, if you're using cheap rx packs, think twice............... there's no such thing as a free lunch!!!!

Heres a link to the cells I use. I had them reconfigured as 5 cell packs with standard futaba/hitec plugs and high quality silicone wire.
http://www.component-shop.co.uk/html/6vp1400afp-w.html

NJRCFLYER2

My Feedback: (42)

Right! They ought to just pull the 4 cell NiCad out and replace with something substantial or just eliminate it entirely, plus amend the manual to explain the proper care & feeding of the receiver from a power standpoint. BTW, I didn't mention it before, but the other poor aspect to the capacitor patch is that a 4700uF cap is going to look like a dead short to the switch contacts at the moment they are closed when turning it on each time. That's bad for the contacts and will shorten their life. The answer - just say NO to the "voltage protector" and get a good set of batteries as you advised.

aresti1963

Actually, higher spec battery packs are my solution to every manufacturers sets, not just Spektrum DX sets. Even standard servos can pull stock AA packs down to low voltage levels. You wont find a standard pack on any of my planes....... been there, done that and swept up the mess!!!
If your pack goes on the fritz, you are going to loose control, NO doubt about it. So, make sure you have the very best pack you can justifiably afford and if you cant afford a pack that can hold it's voltage under the current draw of all of your servos added together............well, I'll leave that to your own thoughts. Redundancy is well worth a second look too!

I'll bet, a few of the problems related here, could have been nullified if the planes had been fitted with better packs. Now, I wonder how the standard DX7 rx pack would fair if it was put under a full 4 servo stall/ amperage drain?? Bet the voltage would be lower than the cut-off for the Rx. No, I haven't tested it, I just eliminate potential problems instead of fixing the ensuing disasters.

NJRCFLYER2

My Feedback: (42)

I'm a big fan of redundancy and use it in anything over a certain size or dollar value. It doesn't have to weigh a lot either. You can make a nice system for even something as light as a Pattern airplane with just a couple of small LiPo packs. I use a pair of TP 2S 730's and some very light regulators and it's lighter than one clunky NiMH and delivers current on demand like nothing else for it's size & weight.

Re. conventional receivers "browning out", sure it can happen! It just seems like the margins are reduced with this particular Spektrum receiver and you have to be careful to choose batteries well.

RobT

My Feedback: (17)

Would these issues be resolved by using two packs instead of one? (even if they were AA packs?)

NJRCFLYER2

My Feedback: (42)

From everything I've heard, it's probably necessary to go to a 6V or slightly higher regulated solution or a 5 cell NiMH unregulated type solution would also work. Personally, I don't like the NiMH packs much anymore due to the higher impedance that most of them have and they also don't seem to age well. The dual pack idea is just for redundancy safety, not really to fix the voltage dropout in normal operation.

As far as the AA packs, it's going to really depend on the servo load you're putting on it as to how well they will perform. These days I like either a dual LiPo regulated setup or even something like the A123 Li Ion would be appealing.

rino

My Feedback: (121)

I did a lot of surfing today and there are plenty of A packs that can handle 20 amp loads without much voltage drop. You just have to be careful with the JR and Hobbico Sanyo cells. As stated elsewhere they are good cells but don't handle much of a load. 4 or 5 amps will bring them to their needs. Cheapbatterypacks.com, onlybatteries and nobs batteries all sell cells that can easily digitals.

I really seems like JR is behind the curve when it comes to rx packs.

Ed

"Personally, I don't like the NiMH packs much anymore due to the higher impedance that most of them have and they also don't seem to age well. The dual pack idea is just for redundancy safety, not really to fix the voltage dropout in normal operation."


Low input impedance for the Rx to look at is important, and two NiCd packs in parallel provide that. Not only do they provide redundancy, but the added capacity of two packs in parallel suppresses voltage fluctuations, and heals drop-outs. All 3 of my Spektrum installations include parallel packs and switch harnesses. DX-7 / AR7000 works as advertised !
> Jim

Hi Craig, sorry to hear about your problems. See you at the field.

jetessmann

My Feedback: (174)

I just found this forum. I had the same problem about two weeks ago and couldn't figure out what happened. I've been flying my Funtana X 100 with the DX7 and 7000 Rcvr with about 30 flights on it, airplane was flying along fine straight and level and just started to decend at about a 45 deg angle no control, took out the nose section and damaged the wings. I was useing 4.8 v pack fully charged. the crash was about 5 min into first flight of the day. I don't think it had anything to do with Tx as I'm using it with my electrics with 6100 Rcvr's and never have a problem. After the crash and I tried the radio and it worked fine but I'm kind of scared to try it again in a new airplane, I have 3 of the 7000's with one mounted in a 1/3 scale Laser, from everything I have read I think I'll got to twin 6 volt packs. Will call HH tomorrow.

RobT

My Feedback: (17)

All of my setups are either twin 6 cell packs, or twin Lipo packs (with regs) I have not gone to spectrum yet but will soon as the modules should be shipping in a day or two.

From what I have seen all of the reported crashes are with single pack setups.

ecoliburger

My Feedback: (18)

Anyone actually heard something from HH? All the suggestions here are speculation,possibly correct speculation, but it would be nice to hear from the people that make the things.
Seems to me there is a real problem with the DX7.

rino

My Feedback: (121)

If you were flying straight and level with a fully charged pack then you probably had very little load on the pack. Why do you think that a different pack configuration will solve this issue. You probably weren't even pulling 1 amp out of that pack at the time.

Some of these crashes like this don't sound like pack issues. Others do but this doesn't. One crash a while back was very similar in nature and with a 6 volt pack. Doesn't anyone think there could be a receiver production issue?

rino

My Feedback: (121)

Are single packs no longer allowed on smaller planes. I don't want to run a $200 duel power setup on a 60 plane.

RobT

My Feedback: (17)

I have to admit you are right. Even though I have lost airplanes because a battery or switch failed and went over to duel setups . . . which if done right do not have to add significant weight or cost . . . does not mean we should have to with any new receiver. If these receivers were designed correctly they would be plug and play into any correctly setup system.

What are you going to do to fix the issue HH?

Is their going to be an issue with the 9000 receiver?

rino

My Feedback: (121)

RobT,

If I were flying more expensive birds I would follow your suggestion to the letter. But, for a 60 sized bird it's not worth it. I sure hope Spektrum comes back with some info on this soon.
OK, real question. On a smaller plane how can I get that redundancy with 2000 mah capacity in about 6 oz of weight?

Jumpnjoe

John- Just a question out of curiosity because our circumstances sound so similar, so far the only difference is you were running a receiver battery and I was not. Let me ask you this: When that plane turned onto final, was the antenna on the tx pointing straight out, and did you turn to face the plane? I didn't realize it at the time, but that's what I did, so my antenna was pointing directly at the plane. I knew (from using 72mhz) that you're not suppose to do that, but anytime I've done that in the past accidentally (with 72mhz), I noticed in short order and just moved my tx away from the plane and the signal came back. I thought (through my own ignorance) that with 2.4 it wouldn't be as big of a deal if that happened (with these short antennas), but maybe it's worse and maybe you can't get the signal back just by moving the tx? Please advise on if your tx antenna was positioned to the plane in that instance like mine was...

sarawnty

I've been following this thread with interest. I have 2 large electric helicopters and a bunch of large gassers on Spektrum. However, I just put my 35% QQ yak and Extreme Flight 88" Yak back on PCM until we know definitvely the root cause. I use single and dual Li-ion battery set-ups with Smart Fly regulators. I'll fly my beaters on Spektrum for now. Steve

rino

My Feedback: (121)

I'm thinking about moving my Spektrum stuff to my foamy until I see at least an explanation that makes sense. For some cases, I don't buy the voltage theory. It's happens but not to guys floating in on final with a charged pack on a glow plane.

flyelectricmodel

Yes, I did have a complete loss of control on one of my three DX7 receivers. It happened on the ground in my front yard after several hours of "burn in time". Had this occurred in the air, it would have cost my model.

My background is 45 years of electronic repair, so was very interested in what happened.

The failure was traced to the DX7 receiver. The receiver was receiving a signal, but all four servos were dead. The failure was traced to a "Plated through hole" on the DX7 receiver, that caused loss of power from the battery center positive lead and all center positive leads of the servos. The plated through hole was not plated through. A quick solder job fixed it. A call to Spektrum resulted in "Never heard of that one before".

The other two DX7 receivers were given a micro-ohm test, no problems were noted. All three receivers have had a number of flights with no problems.

Also ran tests on one of the DX7 receivers on a variable DC supply that allowed dropping the 4.8 volts DC to lower levels. The DC was monitored by my Tektronix 2236 Oscilloscope. Repeated tests showed that the DC had to be dropped to 3.1 Volts DC before the DX7 re-booted itself. The "Patch Kit" Spektrum sells for about $6.00 covers this issue.

Jumpnjoe

Very interesting, fly...
How much will you charge to diagnose mine? Sounds exactly like what did happen to mine in the air.

So, if that is the case, buying that patch kit wouldn't fix it would it?

rino

My Feedback: (121)

Fly,

Would what you describe cause intermittent loss of signal or did it just die after a period of time. Could the rx be made to work again after turning it off and on?

Also, how long would the capacitor cover a low voltage condition for?

If Horizon doesn't seem interested maybe you could charge a fee for inspecting receivers. Or, teach me how and I will open a business. Anyways, I would love to know what to look for. Anyhow, you might want to email them and start a new post on the manufacturers site. Someone at Spektrum needs to get the message.