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Old 01-03-2013, 01:18 AM   #5 (permalink)
Dr. M
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Join Date: Jun 2011
Default Troubleshooting Guide

Pro Tips
- Always check compensation and stick inputs before spooling up. Do it for every pack you plug in!.
- If you're not using the Conditions switching function, make sure the parameters for the 2 banks are set identically to prevent an inadvertent switching of the Conditions mode from causing a crash.
- Quickly Flicking the Gear switch 3-4 times, switching between HH and Rate mode will cause the gyro to reinitialize. Don't do it in flight!
- If you use John_NZ's PC App ( you don't need to connect to the ZYX to update the firmware

ZYX-S Satellite binding issues

USB drivers in Windows 8

Static issues
These gyros are extremely sensitive to ESD. If any part of your avionics system gets zapped by static, the gyro will lose its initialization data and either stop responding, or cause the Swashplate to tilt all the way to one extreme. Symptoms of ESD in flight are easily recognizable: tail twitch followed by a tendency for your heli to want to tilt in one extreme cyclic direction. It usually takes full cyclic input in the opposite direction to maintain a level disk. I suggest you hit TH immediately if you see this happening - this is an extremely dangerous situation and could cause you to lose control. Once the heli is on the ground, examine the Swashplate - it will be tilted all the way to one side and it will not return to center unless you power cycle the gyro.

Take steps to mitigate the static dangers by grounding your tail shaft to the motor mount and using anti-static lube on the belt and plastic gears. For some reason, using a large electrolytic capacitor plugged onto a Y-lead next to the gyro seems to help as well. I use a 3300uF 16V low-ESR cap on my ZYX helis.

Tipover on spool-up or shortly thereafter
Most often these are caused by an incorrect compensation direction on cyclic. Read about the recommended preflight checklist in the first post.

Other possible causes include ESD and vibes.

Here's an example of working thru the possible causes of a flipover (with video):

Brown out testing
Test conditions: used a 4-cell NiCd Rx pack almost depleted. The Rx pack has two leads, one was plugged into a voltage monitor/charger, the other plugged into a free Rx port. I wiggled all sticks until bad stuff started to happen, then started the charger to increase voltage.

Results: the CX-ZYX will brown out around 3.44V. The aftermath of a brown out depended on how long it took for voltage to be restored at operating levels:
1. Fast (<1sec): no reset, everything returns to normal operation with no loss of control. Swashplate level.
2. Medium (1-3 sec): temporary loss of control (feels like a hiccup). All activity returns to normal when voltage is brought back up; the gyro does not reset. Swashplate level.
3. Long (>3 sec): complete loss of control, gyro resets (all leds blink), then fails to initialize (blinking blue led). There's no response from any of the servos, or any other input. Swashplate is frozen in an odd position, cyclic servos buzz, tail servo unpowered. A power cycling is required to restore normal operation.

Bonus testing: I also wanted to see what happened if voltage was maintained at marginal levels for a longer period of time. I set and maintained the input to the system at 3.44-3.45 V. All servos were randomly twitching. There was still response to inputs, but the swash was not level and tail servo wanted to be at the fore extreme (cw piro). Stick inputs resulted in correct response, but upon release, the servos returned to the previous behavior. Increasing voltage above 4V returned the gyro to normal operation (Swashplate level, tail centered).

Known issues without solutions for ZYX FW 3.5
- collective mushyness, doughy feel, particularly in reversals and around center
- random (minor) tail drift in HH mode in a stable hover
- abrupt pitch-up behavior in FFF
CopterX 450 Black Angel FBL "Night Rig" | ZYX v4.0
PRTOS 500 FBL "Sky Whip" | Robird G31
Audacity P6 FBL "Phoenix" | MSH Brain | 12s
Goblin Speed | iKon

Last edited by Dr. M; 01-10-2013 at 03:20 PM.. Reason: added more troubleshooting items
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