Info to repair HC2

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rroos
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Info to repair HC2

Post by rroos »

I've been an avid user and big fan of the HC2 that I used for a local network drive. Unfortunately, the HC2 stopped working today. No LEDs and the power supply seems to generate 12V, so I'm suspecting a problem on the board somewhere. I've already tried booting without SD card and speaker but no effect.

I've seen posts of electrical diagrams of people repairing accidental short circuits on N2 boards. Are similar articles available for the HC2 somewhere? Is there perhaps a typical problem with the HC2 that I can easily try to fix?

Ref: https://magazine.odroid.com/article/rep ... t-circuit/

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mad_ady
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Re: Info to repair HC2

Post by mad_ady »

Before trying to repair - what is the status of the leds? Can you flash a ubuntu minimal image on a spare SD and try to boot that? Can you try booting without the hdd attached?
Do you have a compible (1.8V) USB-UART?

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Re: Info to repair HC2

Post by mctom »

Hi,

Yup, the best bet is to gather as much information as you can before proceeding with any attempts of repair.

I do not have HC2, and I only have one HC1 that was generously donated to me after water damage. I did my best, but haven't found a way to fix it.

Debugging this board is hard as there are no component designates.

Assuming both models share the same schematic (I can't find a separate one for HC2), if none LED is on, that means there is no 5V (P5V0).

The most probable point of failure is 12V to 5V step-down that can be seen on HC2 photos, and is not present on HC1 schematics, because HC1 was powered by 5V in the first place.

Perhaps a detailed photo of your board would tell something more. Please post a photo of your board. You don't need to remove it from the heatsink yet.

Image
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Re: Info to repair HC2

Post by odroid »

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mctom (Fri Jan 07, 2022 8:25 pm)

rroos
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Re: Info to repair HC2

Post by rroos »

Thank you all so much for replying. A picture of my board below is attached. I agree, as much info as possible is valuable before starting to tinker. I can't really see anything obviously wrong on the board from the looks of it though.....
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Re: Info to repair HC2

Post by rroos »

odroid wrote:
Fri Jan 07, 2022 9:38 am
This is the HC2 schematics.
https://dn.odroid.com/5422/ODROID-HC1_M ... 171017.pdf
Thanks for the schematics, but I can't tell from this which component on the board might have the voltage converter?

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Re: Info to repair HC2

Post by mctom »

odroid wrote:
Fri Jan 07, 2022 9:38 am
This is the HC2 schematics.
https://dn.odroid.com/5422/ODROID-HC1_M ... 171017.pdf
Thank you, I have no idea how I missed that one. :D

rroos wrote:
Fri Jan 07, 2022 3:57 pm
A picture of my board below is attached.
The 12V to 5V converter is that bunch of components in the shadow of DC barrel jack, as indicated by the picture I posted last time. :)

I don't think there is anything obviously wrong with the board either... You'll have to measure some stuff.

12V - 5V converter is on page 20 of the schematic - as expected, it's a buck converter, which is based on NB679GD. The good news is this chip is generally available, the bad news - due to IC shortage you might not be able to get it.
It's also in a custom QFN package with long pins extended to the bottom of it, so you'd definitely need a hot air gun to replace it and a bunch of skills (or a local cell phone repair shop).

But first, make sure what is wrong.

First, use your finger to check if the IC is hot, if you don't happen to have Flir lying around.

If you have a multimeter, check voltages between either side of an inductor L15 (the big component marked 2R2) and ground. An oscilloscope would be better to see any possible voltage transients on the upstream side of inductor.

If the chip is hot, and there's solid 0V on either side of the inductor, the chip is toast - more precisely, it's low side MOSFET. That's by far the most common failure mode of Buck converters in my experience.
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