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Jamara Air Jump TX module T8J / receiver 8J

PostPosted: Sat Feb 02, 2013 5:22 pm
by mcross
Hi everyone,

A very good friend of mine bought an Jamara Air Jump remote control, brand new, but he could not use because something is wrong. He asked me to check, so I checked with servos (digital and analog). Everything was ok. Then I checked with electronic speed controller and with a few electronic switches, but this time didn't work.
Then I checked the outputs from receiver with a "RC Multitester" and I notes that the "Frame rate" or "Repetition" from all 8 outputs is (unbelievable) between 37mS and 40mS and very unstable. To be sure, I made same measurements with a oscilloscope and I had same results, the output pulse is ok (between 1mS and 2 mS), but the Pulse Repetition is very unstable, between 37 and 40mS.
Because of that the servo’s are slower and some ESC’s don’t work. I checked 9 electronic speed controllers and 3 works, the other 6 didn’t work.
I measured the PPM signal, directly from transmitter and it is Ok, very clean and stable.
Then I checked the Jamara transmitter with Turnigy 9X module /receiver and works perfect.
Meanwhile I bought myself the same model of remote control (also new) -big mistake- and I found that it has the same problem.
I know that the all R/C system which works in PPM mode use a standard Repetition (Frame rate) around 20mS or 50Hz, or even less if the channels are less than 8.
Because I notes that problem at two Jamara Air Jump, my opinion is that is a software problem.
The TX module (T8J) use CC2500 RF chip and Atmega48 processor and the receiver use the same RF chip, but the processor is Atmega88.

The Jamara TX module is “T8J”, the receiver is “8J” and resembles that of the Corona CT8J / CR8D, at least on the outside.
I attached a few pictures of my Jamara module / receiver and if it is possible I’d like to know if the Corona module / receiver are the same inside.

I made a video with measurments:

http://www.youtube.com/watch?list=UUH3i ... r_embedded

Could anybody to help me? Any suggestions are welcome!

Thank you!

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