AR7100R - Recall Needed...?

[huskynox]

After reading about more then a few complaints about AR7100R primary antenna failures I decided to take a look at mine, which is still brand new in the package awaiting my 90.

I opened the case to look at the soldering joint on the primary antenna, but really couldn't see much because there's some sort of yellowish colored epoxy over the solder joint. I recall "finless bob" saying he thought the failures were due to poor "wicking" of solder into the antenna wire before being soldered to the board. Well, as you can see from the attached pictures it's very hard to tell how the antenna is soldered to the board.

This whole problem makes me nervous. Flying a 50 size or 90 size heli around is dangerous to begin with (as we all know). To have a receiver fail scares the hell out of me! Spektrum already had a similar problem with the AR9000's being used in a high vibration application....they were having a capacitor break off the board. They did release a service bulletin on the AR9000.

I emailed Spektrum about the problem, but haven't heard anything back.

Thoughts? Experience with one failing?

http://www.helifreak.com/attachment.php?attachmentid=54512&stc=1&d=1215796282

http://www.helifreak.com/attachment.php?attachmentid=54289&stc=1&d=1215613658
http://www.helifreak.com/attachment.php?attachmentid=54513&stc=1&d=1215796282
http://www.helifreak.com/attachment.php?attachmentid=54290&stc=1&d=1215613658

[Ultraviolet]

In the first picture it looks like there is poor solder wetting on the voltage regulator.

as far as the antenna.......put a small drop of CA on the wire where it exits the strain relief. By bonding it to the strain relief it will make that the fatigue point, thereby isolating the solder joint from any external force.

[CatchmyCorsair]

I'm in the same position: worried.

But I think I might remove the rubber boot and put some hot glue around the wire on the board making sure it secures the bottom of the wire. (weak point)

I think the board must be vibrating inside the case, so removing the boot will allow the wire to vibrate freely with the board. The boot is the only thing I see that could cause the wire to vibrate enough to the point of failure.

Let us know what Spektrum says.

[ping]

I think the board must be vibrating inside the case, so removing the boot will allow the wire to vibrate freely with the board. The boot is the only thing I see that could cause the wire to vibrate enough to the point of failure.


The helicopter is transferring high frequency vibes through the case then through the rubber boot to the wire. The vibrations are probably causing the solder joint to fail at the point where the solder ends inside the wire. Two fixes for this is to use a solid gauge wire and re-solder it to the board, or use a mechanical strain relief on the board itself.

[CatchmyCorsair]

The helicopter is transferring high frequency vibes through the case then through the rubber boot to the wire. The vibrations are probably causing the solder joint to fail at the point where the solder ends inside the wire. Two fixes for this is to use a solid gauge wire and re-solder it to the board, or use a mechanical strain relief on the board itself.

Right. The strain relief is too far out on the wire. Needs to be right near the board. So I'll just be removing the boot and adding some hot glue at the board for strain relief.

But creightoncarr still had one come off after hot gluing at the board. That's why I'm still concerned.

[HowNot2fly]

not to bash spektrum (i realy like my dx7 and ar7000) but they dont respond to any emails,you will have to call`em and talk to them on the phone,

[Ultraviolet]

Oh, you guys are concerned about the circuit board bouncing around inside the case. Is that correct ? I thought you were concerned about external antenna strain.

Pop open the case and put a piece of foam on the top and bottom of the circuit board. Just thick enough so that when you snap the case together, it will compress the foam slightly......No more vibration issues (inside) the case.

[CatchmyCorsair]

Oh, you guys are concerned about the circuit board bouncing around inside the case. Is that correct ? I thought you were concerned about external antenna strain.

Pop open the case and put a piece of foam on the top and bottom of the circuit board. Just thick enough so that when you snap the case together, it will compress the foam slightly......No more vibration issues (inside) the case.

We are concerned about the wire fatiguing at the solder joint. I think shoe goo (goop) might work better than hot glue at the joint.

But also notice the center board can vibrate a little between the two. (see white foam pads)

[EASYKILL]

My Stratus has about 15 flights with a 7100R and two satellite receivers. On my last flight I had my canopy off (for another reason) and noticed there was no amber light illuminated indicating signal on the main receiver. I foolishly flew it any way and had no problems. When I got home I took the 7100R off and opened it up. Sure enough once I had the bolts loosened the antenna wire fell on my lap.:thumbdown: If it wasn't for the extra sattelite... This is a brand new machine with top of the line everything (except for receiver apparently) with well over $2000 in it. If it had totalled itself due to signal loss what then?:FanI am having a friend who is very capable with small electronics fix it right because I just don't trust Spektrum any more. Any body want to trade a 2.4 9303 for a DX7??

[lrrps]

I just applied silicon sealant on my 7100, is that OK?

Thanks.

[Pinecone]

BTW to make SURE that the word gets out tothose subscribed to this thread, there is now a Service Bulletin out on the Spektrum site about this. Funny, Spektrum says they have only seen 3 cases of this, maybe some of you ought to call them and set them straight. :)

http://www.helifreak.com/showthread.php?t=84763

VegasBob seems to only want to use his thread for getting the word out. :)

[VegasBob]

Huskynox,

Do you have a feel for how big this antenna problem is? 1 in 5 receivers have the problem, 1 in 50, 1 in 1000? I certainly think it's a lot more than just three receivers. If I end up using the 7100, I'm going to buy an extra satellite receiver just in case.

[lrrps]

Huskynox,

Do you have a feel for how big this antenna problem is? 1 in 5 receivers have the problem, 1 in 50, 1 in 1000? I certainly think it's a lot more than just three receivers. If I end up using the 7100, I'm going to buy an extra satellite receiver just in case.


How do you connect the extra satellite receiver?

[Ultraviolet]

How do you connect the extra satellite receiver?

Plug it in. ;)

[huskynox]

I have no idea how big the problem is. Finless Bob would have a better idea.

I will indeed do the Shoe Goo trick that Spektrum suggests, AND will run 2 satellite antennas

You can run 2 satellite antennas because the AR7100 has 2 ports for 2 antennas.

[VegasBob]

The extra satellite antenna is only $25. Small price to pay to protect $2000+ worth of equipment.

I think this problem is a lot bigger than Spectrum is letting on. At least a lot bigger than just three receivers.

[noste500]

I have just mashed up my new t700 with ar7100r failure,
The ariel still looks to be intact, but all cotroll was lost. I posted the info in the thread I started in the Trex 700 section if you want the full info, take a look there.
cheers

[Priapismic]

Mine still went nuts even with the second remote. I had intermittant control (about 1/2 second at a time). I'd like to know how many others have had problems. I posted a poll in this section to find out.