Originally Posted by philagan

In reading your thread's your knowledge of tec problems my help me find an answer
to my 42 % sukoi crash. After 35 flights on it I traded modified wings (larger ailerons)
with 7980 servos for new wings and 7954 servos ,Brand new in the box.
Using my spectrum DX18 Xmtr I programed the new wing servos as before,on the
very first take off after about 100 feet I lost all control,Plane flew about half mile before crash. At crash 3 sat ant were on solid # 4 was disconnected all 4 servos in the tail would not move. Later at home performed bench test ,servos would not move until
I exchanged A with B then they worked ??? Sent the 12 x powersafe rec to Horizon ,They could not duplicate the problem and sent me a new rec.
The only thing I noticed was a strange sound out of the wings when the servo moved.
I installed the servo in a 42% aero works yak and they made the same noise, I removed the 7954s ,and will not use them until I figure this out. I have moved on to Brushless servos in the Yak.
I think the servos set up an oscillation feed back that took out the 2.4 receiver.
I talked to a Electronics Engineer in RF tec about it ,said it could happen.
Note ;I have used Hitec 5955 7955 7950 ,7980 , and now 9380s Dx18 xmtr 12 ch
pwrsafe rec , 6.6 v and 8.4 v for years with 100% confidence ,but not any more.

Philagan

If you read the 12 channel PowerSafe instructions you will see that they say that at least 3 remotes are required, one of which must be connected to port A. There was most likely nothing wrong with the PowerSafe, it simply refused to connect because there was no remote connected to port A when you bench tested it, which is a requirement for it to connect. Before you get worried, once it connects to your DX18, if the remote connected to port A fails or get unplugged, everything will continue to work just fine until the next power cycle, where it will refuse to connect. Since Horizon was nice enough to replace the PowerSafe, I only mention this so that you don't run into this issue again in the future.

Did you perform a range test before flying? Since control was lost once it got 100' away I assume this should have showed up during a range test. When you returned the PowerSafe to Horizon, did you send your DX18 back to get it checked out as well? Before flying another airplane with it I would thoroughly range test it as the DX18 could well be the problem due to reduced RF output. Don't assume the only place the problem could be was inside the airplane..

Wayne

Hey Wayne Thanks for the reply More info, Port A sat broke connection in crash ,the other sats should have continued to operate . I have continued to use the DX 18 without any problems.,on low
value planes.I sent 12 pages of data log info to Horizon.In all of the test ,Log showed only 2 "F" and no "H' I think It went solid H and fail safe never activated. Remember I had over 35 flight s before I changed wings. I have installed telemetry now in my Yak , But have not flown it yet,
waiting for the wind to stop blowing
Philagan

For those who have lost trust and no longer wish to have any Hitech servos (59xx, 79xx) in their planes, I will gladly purchase any from you for $10 each. Hitech has been constant winner in all my planes for 12 years without one hitch or failure.

I know this is an old thread but I just purchased 2 - 7950 for my 35% Edge. I have been using 7955 with no problems. After installing the 7950 (2 on elevator) the one side jumps as described in the thread. So apparently the problem still exists. I called Hitec and they told me of the issue. I can not believe this is still an ongoing problem. They are sending me 2 signal boosters. So does this actually solve the problem? I can be confident? If not, I will change out for other servos.

Thanks peeps...

What size extension wire are you using? 20gage, maybe?

The heavy duty twisted. Never had a problem before using 7955's.

Boosters will stop the twitching, place them at the servos.

The problem is not with the servo but the signal the servo is seeing. Long story short, the signal has degraded enough to where the servo no longer sees a good strong signal and therefore jumps because of the fuzzy signal. A signal line booster amplifies the signal coming from the receiver so the servo sees a strong and clear signal, it's a fix that we developed to solve the issue and it's something that we, thus far, have not heard any negativity back from any of the end users we've sent the boosters to (I would use them on my own airplanes without issue if I needed to). Mainly we only see the issue in conjunction with PowerSafe receivers but poor extensions and bad contacts in the extensions can also create issues. Rarely is it ever an issue with the servo itself but you are always more than welcome to send the servos into us for a checkup if you suspect it's the servo causing it.

You can think of the issue like 2 people standing a great distance from each other trying to give directions. If person A just uses his voice to shout directions at person B then person B may not hear the directions clearly. If person A uses a megaphone to amplify his voice to shout the directions then person B can hear those directions much more clearly.

Originally Posted by johnatbnsf

Boosters will stop the twitching, place them at the servos.

Don't you place the booster at the receiver? In my case the XBUS XPORT Duo hub? Then into the extension? Boost the signal from the receiver to the servo?

You can place them at the servo or at the receiver side, doesn't really matter.

I just feel the need to chime in on this issue. I have been using the 7950's for over four years now. Not one...not a single one has had any issues whatsoever at all. Other than when I bailed ship for what I thought would be a better radio system. I went "TEMPORARILY" to a brand new JR XG11. Not only did my 7950's have a spas attack, but everything else seemed quite "twitchy". Dumped the JR and went back to my faithful and dependable Aurora X9. Problems exited, stage left. And have never returned. The 7950 is a rock solid brute servo.

Update: I switched the 7950 elevator (problem servo) with the 7950 pull/pull rudder servo. Seems to have eliminated the issue. Working great so far. I will keep testing but it didn't glitch once. Some servos must be more sensitive to signal degradation than others. Would it be a good idea to still place the signal boosters on the elevator servos when I receive them?

Thanks...

It won't hurt to use the booster. Servos are going to have some minute variances between them due to how servos are assembled.

....

I lost 3, 7955, motors went sour, sent hitec, I don't keep receipts some I buy new, some used, all 6 of my 150cc planes had these servos. They refused service even after I sent them pics of more than 50 servos. They offered me a meager 10% discount on new. No more. Hello JR.