Odroid N2 Repair: Red Power LED won't light, Blue Power LED Blinks

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beaker23
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Odroid N2 Repair: Red Power LED won't light, Blue Power LED Blinks

Unread post by beaker23 » Mon Nov 11, 2019 1:31 pm

So for a little background I've had two Odroid N2's that have had this problem, likely due to my finger rubbing against the +5V and GND on the board located at the GPIO on pins 2 and 4. Having these two pins next to each other, together with the power connector being on the board diagonally across from the GPIO seems to pose an ergonomic problem to some extent. I tend to hold my hand near the GPIO pins while removing the power connector from the board when I am installing a new eMMC module that has just been flashed. By my thumb accidentally making an electrical connection across these pins it seems to damage the board. The first one I had this happen to was replaced under warranty, the second was out of warranty. I believe they have repaired the problem already with a modification to the circuit board.

I decided to dive into the schematics to see if I could manage to find a component on the board that could be replaced to repair the problem. From analysis of the circuit it appeared to be U12 on the board, which is P/N/ NB679GD. This component happened to be very small, with some solder connection to the board on its underside and a lot of pins on it. So instead of attempting to remove and replace it I went another route that seemed like it should work due to the way the circuitry on the board is layed out.

My plan was to bypass the U12 chip, and solder on a 12V to 5V power supply onto the back of the DC Barrel jack. After this was accomplished, I could wire the +5VDC output and GND to the board's GPIO pins on pin 2 and 4 to provide the circuit board +5V. From reviewing the schematics this did not seem like it would cause any problems, and should work.

In my case it did. From the pictures you can see how I attached the power supply, I used this one merely because I had it on hand with my electronic supplies. A smaller one would probably be better, I don't think I'll be able to put a cover back onto the odroid.

For now it is working again, I was able to boot the board with an eMMC module installed and connect it to some USB peripherals and an HDMI monitor. The RTC seems to not be working on that particular board at the moment, but that may be a different problem with the board or something in the software that I need to mess around with.

But good news is, if you have a board with the problem where the Red power LED won't light, and the blue one blinks it may be possible to revive it and get some more use out of it like I did.
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odroid (Tue Nov 12, 2019 9:46 am)

nurikodd
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Re: Odroid N2 Repair: Red Power LED won't light, Blue Power LED Blinks

Unread post by nurikodd » Mon Nov 11, 2019 1:58 pm

Hardkernel definitely should add some protection circuit around gpio in future boards

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mad_ady
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Re: Odroid N2 Repair: Red Power LED won't light, Blue Power LED Blinks

Unread post by mad_ady » Mon Nov 11, 2019 2:02 pm

Out of curiosity - what value do you get if you try to measure your internal resistivity with an ohmmeter on your finger? Also, were your fingers wet/sweaty/greasy when you touched the gpios?

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Re: Odroid N2 Repair: Red Power LED won't light, Blue Power LED Blinks

Unread post by beaker23 » Tue Nov 12, 2019 7:52 am

Don't think I'll try. Hands weren't sweaty or anything, just the normal conductivity across the skin which is probably near zero going across the surface.

I used some IDE connectors to cover the GPIO on the other boards that I have, so it doesn't inadvertently happen again. I'm not using the GPIO on those, so I'm ok to just cover all the pins.

The XU4 has a style of GPIO connector that provides some protection from this.

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