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Saturday, April 25, 2009

EVO 12 Troubleshooting

Recently, my faithful EVO 12 decided to give up on me. Here are the symptoms. The right stick (for elevator & aileron control - I'm a mode 2 user) fails to respond. If you go under the Servos -> Monitor menu, both CH 1 & CH 2 show the bars in 100% end-to-end position. Similarly no respond by the right stick movement, but left stick movement shows the bar responding accordingly. I suspect to be the 74HC4051 chip or the Micro Controller (CPU) that is having problem.

However, thanks to Mike from

Here's what he said.

The earlier production of the Evo's did have a problem with the wires to the stick pots, but this tended to only effect the horizontal stick pots. If your transmitter pots wire include yellow as the middle wire on the horizontal pots then this suspect wire. All of the main stick signals go to the main CPU chip, so I don't think it will be the 74HC4051 chip. I suggest that you measure the voltages at the pots it is around 3.28 across the pot and a centre voltage of 1.8 volts. Don't forget to remove the RF board from the transmitter so that the RF doesn'teffect the DVM reading. If that seems OK, I would then check that the voltages appear at the plug and socket for that stick on the main board. If that all seems fine then it's possible that the model data have become corrupt, so you could try sending a blank models data to the transmitter. Which is like resetting the transmitter to factory setting, this is available in the data manager program which you can get off the Multiplex web site.

All the hardware checks show things are in order & hence I tried reloading the software as recommended by Mike. However, after several software reloading tries, something new shows up. Like the Welcome Tone on powering up is now gone and the EVO keeps going into the Servos Menu after start up.

Luckily with Mike's advise again.

From what you are saying, it tell me that the transmitter has lost it's stick and slider calibration. Here is the proceeded to re-calibrate the sticks and sliders.
  1. With transmitter off centre all of the sticks and the sliders.
  2. Switch the transmitter on and then move each stick in turn to one end of its travel and wait for the LED by the ON/OFF switch to go out. If the transmitter tells you to move the throttle stick low, as you switch on make this the first stick to be move to its end of travel.
  3. Do the same with the 2 slider controls.
  4. Once you have completed this operation use one of the digi knobs to get out of this menu by dialling out to exit until you get to the normal display. The voltage level will show 0 volts at this point.
  5. Now switch off the transmitter and the calibration data will be stored.
  6. When you switch the transmitter back everything should be displayed as normal i.e. voltage and trims etc. If the transmitter goes back into displaying the stick data i.e. percentage numbers it means that the calibration was not completed or not done correctly.
And Walla! My EVO problems are solved & it works just as fine as it did before. My sincere thanks to Mike!