jim52519

My Feedback: (3)

Hi All
This is not a jet question but perhaps someone here was had this problem. I am setting up the radio gear in a 106" Hurley Extra I built. I am using a Spektrum DX7 TX and an AR7000 RX. I am using Hitec HS-7955TG servos.I am using 2 elevator servos. I used an Elevator to Aux2 mix so I could use 2 servos. When I test the setup the servos move very spastically. It could never be flown like this. I went through the radio programming about 3 times. Always the same result. I then plugged 2 JR servos in place of the Hitecs and the JR's worked flawlessly. Are Hitec servos not compatible with a Spektrum radio????? Am I doing something wrong? Has anyone else had this problem?
Thanks,
Jim

Selleri

Is the Tx set up like this? > [link=http://spektrumrc.com/Articles/Article.aspx?ArticleID=1798]http://spektrumrc.com/Articles/Article.aspx?ArticleID=1798[/link]

Are using high voltage unregulated?

gooseF22

supposed to be fully compatible. Do you have a hitec programmer? set the servo's to the minimum deadband if you do.

Did you try a different receiver or transmitter? or a different satellite receiver? just a couple ideas that come to mind. Thats strange behavior...


What is your power supply voltage? I havent used the 7955's yet, but I have alot of the 5955's on spektrum. Will they sit quietly when no movement is present? Try testing the setup with a simple 4 cell pack to see if it still does it.. IF the Jitter goes away on a simple 4 cell or 5 cell pack, your power system needs to be dialed down in voltage or its delivering dirty voltage.. That said, I have seen 7955's running just fine on 8.4 volt Lipos direct, so Im shooting in the dark.

Note: the Spektrum article says leave Flap system in SYS. Not sure I agree, all mine set up with dual ailerons are flap INH, unless you want to use reflex/flap modes. I dont think that affects his setup though..

jim52519

My Feedback: (3)

I am testing the set up on a 2700 mha 4 cell NIMH pack so the voltage should not be an issue. I do not have a programmer. The symptom is that the servos moves in the correct direction but there is a delay. They do not smoothly follow the Tx stick movement. It is very pronounced. I did program the Tx just like the link in the other post. The fact that the JR servos work ok makes me think the programming is correct.
Jim

trioval00

My Feedback: (17)

you might have either a bad receiver or a bad servo. unplug all of the servos. one at a time , plug one servo in if it works fine, unplug it and try another servo. try every servo. as for the battery, if it has a full charge, that can make your servos act strange


Mark

jim52519

My Feedback: (3)

I think I solved my problem. I tried the same servos with a Futaba RX and TX and had the same poor result. I was starting to think the servos were bad but then I tried a 5 cell battery pack and the problem disappeared! I think there must be something wrong with the 4 cell pack. It is an old pack I was just using for set up. It measures ok on an ESV but must not deliver the necessary voltage under load. With the 5 cell pack everything works great! I guess do not assume a pack is good even if it measures ok on an ESV. Lesson learned.
Thanks,
Jim