February 21, 2024, 02:43:04 AM

Recovering from Overvoltage

Started by baffo32, August 13, 2020, 01:20:21 PM

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baffo32

Hi,

I have an unfortunate habit of plugging my teres into 12v supplies, which immediately burns the board out.

Does anybody know which components on the board will need to be replaced after this?

Thanks so much.

LubOlimex

You can look at the top left corner at the forth page of this document - it shows the power circuit around the power jack connector: https://github.com/OLIMEX/DIY-LAPTOP/blob/rel3/HARDWARE/A64-TERES/TERES-PCB1-A64-MAIN/Rev.C/TERES_PCB1-A64-MAIN_Rev.C.pdf

First try replacing D1 SMBJ6.0A. There is good chance this diode protected further damage. If replacing it doesn't work, then the AXP803 got damaged and the chances of repair are slim.

In future consider adding a protection fuse, where the suggested FUSE2 is placed in the schematic.
Technical support and documentation manager at Olimex

baffo32

Thank you here. I keep accidentally doing this. To add the fuse it looks like you would physically cut the wide trace the fuse almost fully spreads over, verifying afterward the two solder pads no longer conduct, and then solder an smt fuse over? The trace appears to partially spread under D1 so some delicate knife work may be needed I'm thinking.

LubOlimex

#3
Yeah the wire is a bit thick because there is a lot of current going trough. Just cut between the two pads of FUSE2 up to D1 (and probably some under it). If it was me I'd do it starting from D1 down towards the FUSE2 pads. Some sharp cutter is needed. Also double check if the cut is properly done afterwards with a multimeter tool in short circuit detection mode. Maybe unsolder D1 temporarily or one of its ends if in the way. Once the cutting is done place the fuse.
Technical support and documentation manager at Olimex

kreyren

Referenced in https://github.com/OLIMEX/DIY-LAPTOP/issues/61 to propose adding a resettable fuse to mitigate the risk of over-voltage due to pebcak.
* Community Lead Developer of Teres-2
* Maintainer of OLIMEX Teres-I on Armbian, NixOS, PostmartkerOS/Alpine
* Co-Author of an Official OLIMEX Teres-I support for Parabola GNU/Linux
* World record holder in annoying Tsvetan with questions about OLIMEX Teres-I hacking

LubOlimex

We would consider it but if you are capable for replacing the fuse or resetting it you'd be capable to place it initially. Better to link your suggestion for fitting fuse here.
Technical support and documentation manager at Olimex

kreyren

Quote from: LubOlimex on April 03, 2023, 10:28:12 AMWe would consider it but if you are capable for replacing the fuse or resetting it you'd be capable to place it initially. Better to link your suggestion for fitting fuse here.

See my reply in https://github.com/OLIMEX/DIY-LAPTOP/issues/61#issuecomment-1495047014

Tl;dr: The fuse is e.g. https://eu.mouser.com/ProductDetail/onsemi/NIV6350MT2TXG?qs=xZ%2FP%252Ba9zWqa2xJAD3VNXxQ%3D%3D, seems to reset itself without the need of user interaction.
* Community Lead Developer of Teres-2
* Maintainer of OLIMEX Teres-I on Armbian, NixOS, PostmartkerOS/Alpine
* Co-Author of an Official OLIMEX Teres-I support for Parabola GNU/Linux
* World record holder in annoying Tsvetan with questions about OLIMEX Teres-I hacking