Magic smoke and broken LCD shilds with 15V

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the_glu
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Magic smoke and broken LCD shilds with 15V

Post by the_glu »

Hello,

I got 3 C4. Based on the page's spec, they are supposed to handle 15.5V, so I used a 15V power supply from odroid.

Initially everything was fine, but when I added EMMCs cards and plugged them back one odroid released some magic smoke around the Ethernet connector. All 3 also doesn't have anymore the red LED light fully up.

I also had the 3 LCD shild plug-in, and the 3 doesn't light up anymore. The 8 leds on them are fine through.

I checked the voltage of the power supply, who is around 15.05V, so in spec. This should not have destroy the C4s.

What should I do ? :cry:

Thanks and have a nice day,

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Re: Magic smoke and broken LCD shilds with 15V

Post by the_glu »

Quick update: looking at the board, it's seem that U25 is dead.

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Re: Magic smoke and broken LCD shilds with 15V

Post by the_glu »

Re-quick update:

I did test the LCD screens on another not-burn-C4, and only one is dead (probably the one who was with the magic-smoked one).

The 5V voltage on the magic-smoked is around 0V, the other 2 are around 1.4V, that would explain the red led behaviour (and based on the schematics, U25 is providing the 5V).

The 3.3 voltage seems fine on all cards.

fvolk
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Re: Magic smoke and broken LCD shilds with 15V

Post by fvolk »

the_glu wrote:
Tue Mar 16, 2021 6:20 am
I got 3 C4. Based on the page's spec, they are supposed to handle 15.5V, so I used a 15V power supply from odroid.
I can confirm running 3xC4 with a Y-cable and one 15V/4A PSU (originally intended for the H2) runs just fine.

Maybe your PSU is/was faulty? :-/

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odroid
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Re: Magic smoke and broken LCD shilds with 15V

Post by odroid »

Some PSUs might generate random transients (over-shoot) voltage and it probably damaged the component(U25, 5V buck converter IC) due to its tight tolerant.
I think we need to lower the maximum voltage range to 13Volt in the specification.

Anyway, please contact "odroid at hardkernel dot com" with a URL of this thread.
They will help your RMA process if you purchased the board from our web-store directly.
Otherwise, contact your local distributor/reseller. Sorry for the inconvenience caused.
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the_glu (Tue Mar 16, 2021 6:45 pm)

jgmdev
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Re: Magic smoke and broken LCD shilds with 15V

Post by jgmdev »

The same happened to me while doing hc4 and c4 images testing where I used the hc4 cord instead of the c4 one so this really holds true, be careful folks and don't make the same mistake :D

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mctom
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Re: Magic smoke and broken LCD shilds with 15V

Post by mctom »

Many power supplies have higher output voltage than specified when without any load. The situation is resolved when you load the PSU, but if output capacitos are big enough, the rush of overvoltaged current may break things here and there.
What can I say, input TVS is your friend...

And from the user's perspective, it's probably better to plug the PSU to the SBC, and then to the wall. This way it will always have a load and solve the issue, as long that was indeed the issue in the first place.
Punk ain't no religious cult, punk means thinking for yourself!

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