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Old Oct 31, 2015, 06:13 AM
Hump101 is offline
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JR XP642 reversed polarity

I appreciate this is an old radio, but I opened it up to fit an FRSky 2.4GHz DIY module, and through a combination of the connector falling off the battery, the wires being red for negative, and gross stupidity, I reversed the polarity. There was a loud pop and a dead unit.

The only component on the main board that has failed, AFAIK, is shown in the attached photo. Can anyone identify this component so I can replace it? It is the first component next to where the power comes into the board.

It's a long shot but I thought I might as well ask! If you need any more info just shout.
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Old Oct 31, 2015, 09:50 AM
ivanc is offline
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it is a 78L05F voltage regulator. The problem with reversed polarity is that the reversed voltage goes through D1 (seen on the picture) ending up on the 5V rail going to all components including the MPU. My guess is none of the ICs expecting +5V survived -10V. Unlike capacitors and voltage regulators they do not always show obvious signs of failure.

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