[Help] I short circuited my board

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neryneto
Posts: 6
Joined: Wed Dec 05, 2018 12:42 am

Wed Dec 05, 2018 12:56 am

Hello, it is my first post here.

Unfortunately I have done something very stupid. I made a DC battery for the board, but i did not have the correct 4 pin connector, so i used protoboard jumpers, but they did not fit properly and i got the hood off of 2. When i was unplugging the battery i did not get all 4 at the same time and bad thing happened, i saw a small spark and i think the positive and negative touched... yeah =/

This is embarrassing to say the least.

My model is Alpha 800, since this happened no led lighten up when i connect the usb c power.

Anybody know how i could fix this? Maybe replace the integrated circuit responsible for power, really anything at this point is welcome

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neryneto
Posts: 6
Joined: Wed Dec 05, 2018 12:42 am

Wed Dec 05, 2018 9:22 am

I was wondering, maybe there is a safety fuse.

Where could I find a detailed pcb description of the lattepanda alpha? Maybe i was lucky and it's just a fuse replacement

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ccs_hello
Posts: 631
Joined: Sat Oct 13, 2018 9:16 pm

Wed Dec 05, 2018 2:30 pm

AFAIK, there is no fuse.
However please note that the DC_In power and USB type-C power feed are two independent circuits
so likely the other side has no problems.

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neryneto
Posts: 6
Joined: Wed Dec 05, 2018 12:42 am

Wed Dec 05, 2018 2:50 pm

Thanks for help ccs_hello,

It is not powering either from DC-in or USB-C, this might be a bad sign.

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neryneto
Posts: 6
Joined: Wed Dec 05, 2018 12:42 am

Fri Dec 07, 2018 12:59 pm

Update:

Doing some tests I figured out which part was damaged, it was a small chip that used to be on the red circleImage:

We removed it from the board and did not find any other component heating up with power on.

I suppose it is some sort of voltage regulator, I could no quite read properly the letters are too small, but I think it was written "DDJ 381" on it. Does somebody have the datasheet of this chip? Can i order one for replacement or find another chip that does the same function?

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LattePanda
Site Admin
Posts: 2657
Joined: Wed Jan 20, 2016 9:09 am

Wed Dec 26, 2018 3:12 am

Let me invite our engineering team to support here directly.
Enjoy Tinkering with LattePanda ! :lol:

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neryneto
Posts: 6
Joined: Wed Dec 05, 2018 12:42 am

Wed Feb 06, 2019 1:54 pm

Hello,

Any news? I just need this part number and possibly where to get another one of these, but if that is not viable, if I can not buy only one tiny part as a consumer just let me know.

Thanks!

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ccs_hello
Posts: 631
Joined: Sat Oct 13, 2018 9:16 pm

Wed Feb 06, 2019 2:25 pm

That 6 pin IC (SMD marking DDJ 381) seems to be some sort of MOSFET.
Please check the PCB pattern (3 tied together on one side, 2 tied the other side, and one pin for Gate.)
Check voltage relative to GND. If it is positive on either the S or D lead, then it's P-ch MOSEFET, most likely for power path control function.
Don't hold me on this, just a guessing.

Also note, short-circuit further downstream will cause this MOSFET to burn out. So the issue may not be just this.

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