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Sep 16, 2011, 04:38 AM
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Turnigy 9X Transmitter - reverse power regulator repair + LIPO Battery Mod + Links

HobbyKing 9X Tx'r, (love the 9X, great quality and features for the price)

I accidentally reversed the power trying out a LIPO battery in my 9X. Now this is not as difficult as it sounds, and given that I'm an electronics Tech, somewhat embarrassing.

The 9X battery plug is the same style as a LIPO 2S charging plug, but be warned the wiring configuration is different. I made an adapter for a 3S and ended up reversing the supply voltage to the Tx'r which smoked some components.

I ended up having to replace two 5V regulators and a capacitor (one regulator was in the Tx module, details available in the links).
During repairs I also incorporated the LIPO 2S battery mod (which uses an additional resistor to trick the Tx regarding the battery monitoring voltage). Note, if you measure out and check the schematic, component mounting can be simplified as I've done.

Another option for the battery Mod is to do a er9x firmware update so you can just dial in the voltage you want the Tx'r battery to alarm at (you won't need the resistor mod then, but you will need another hardware mod to do the firmware upgrade plus you get a whole lot more options available for programing).
Note: 2S LIPO is more efficient than 3S, as the Tx'r regulates down to only 5V anyway.

LIPOs: I used two 2400 LIPOs with auto charge/dis-charge cut off (don't know for sure if this will protect the battery if Tx'r is left on, it does restrict max charge voltage).The batteries I used, will not fit side by side in any configuration, I cut my bay for this fit.
The 9x battery alert is set to go off at 8.8V (displayed on the Tx). The additional resister worked well to trick the 9X sensor voltage using the LIPO's.

Results: My charger could not charge above 4.14V p/cell (due to battery circuitry) good enough! The charged 2 LIPOs actual voltage of 8.2V reads 10.4V on the modified 9X display (with resister mod). The 9x 8.8V battery alarm tripped when the 2S got to 3.25V p/cell (6.5V).
I got 10.5 hours from a full charge until the 9x 8.8V alarm went off. Happy.

Links for schematic (circuit diagram), battery Mod, repairs, good 9X info
Circuit diagram
er9X Firmware Mod
Battery Mod
Main RCgroups thread
replace burnt regulator thread
ER9x site - repair thread
More regulator repairs (post 1672 on)
CX2Mike's repairs
more repairs 2
A new battery supplier (also has unprotected version)
My Blog (Performance wing reviews & builds, Laminate covering film info, etc...)
frsky telemetry on turnigy 9x without rs232/transistor/flying cables/holes

New FrSky radio (Tipped to be better than 9X & 9XR).

Last edited by cleansurf2; Apr 01, 2013 at 03:54 AM.
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