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Mantis Q does not turn on. Motherboard power supply failure.

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Hello users and moderators of this excellent forum!

I would like to share my experience repairing the Mantis power system.

I recently received a Mantis Q after a fall from a height. The symptoms of the damage were that the drone could not be turned on despite the green on/off switch LED being lit. After releasing the switch (after a few seconds), the LED went off and there were no beeps.

Initial measurements of the voltages at the test points revealed a problem in the power supply circuitry on the motherboard.

The cause was a faulty 12V/5V converter chip with the symbol RT7239GSP located on the reverse surface of the motherboard visible only after removing it from the drone body.

The RT7239GSP chip is a synchronous step-down DC/DC converter in a SOP-8 (Exposed Thermal Pad) enclosure.

Removing and soldering the new chip required some effort and preheating of the PCB because the lower heat sink (Exposed Thermal Pad) is soldered to a large area of copper with lead-free solder with a higher melting point (RoHS requirements).
In addition, RT7239GSP chip in SOP-8 package, according to the catalog note, has max. allowable soldering temperature of 260°C within 10 s. Be careful.

After replacing the RT7239GSP chip Mantis Q boots up normally.

The picture show the motherboard with the place of mounting the RT7239 chip protected with Kapton tape during soldering.
 

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DoomMeister

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Good troubleshooting and great write up.
 

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