Khadas VIM3 - 12V went into SPDIF

in-sympathy · January 20, 2025, 11:40am

Hi all.

My mate asked me to help fixing his VIM3 that was used in his car.
Accidentally he sent 12V on SPDIF.

I’am really good at soldering anything, but would appreciate your experienced help with hints on what to check on the board.

From what I can see now - 0.8V, 0.9V, 1.1V on RAM, 3V3 and 5V are all present. USB voltage is also present.

Can’t see any obvious shorts on any caps or heat spots with an infrared cam.

If I press F button 3 times at boot - blue LED flashes with either 1-2-2, 2-2-2 or 2-2-1 patterns.

Any help is greatly appreciated.

in-sympathy · January 20, 2025, 4:05pm

would really appreciate a comment from someone on the engineering team - what does pin 13 connect to? Is it going straight to the CPU? Which parts should I check if 12V were pushed into pin 13?

Electr1 · January 20, 2025, 4:42pm

@in-sympathy If a complete current loop was not created, then there is a chance nothing may have happened.

The SPDIF pin is connected directly to the SoC. Does your board boot normally, and is anything displayed when only a screen is connected ?

in-sympathy · January 20, 2025, 5:54pm

Hi, thanks for getting back to me on this.

Absolutely nothing is being displayed, however:

From what I can see now - 0.8V, 0.9V, 1.1V on RAM, 3V3 and 5V are all present. USB voltage is also present.
If I press F button 3 times at boot - blue LED flashes with either 1-2-2, 2-2-2 or 2-2-1 patterns.

Electr1 · January 21, 2025, 2:07am

Can you try to burn new firmware to the board ?
https://docs.khadas.com/products/sbc/vim3/install-os/install-os-into-emmc-via-usb-tool

https://dl.khadas.com/products/vim3/firmware/android/vim3-android-9-64bit-v241023.img.xz

in-sympathy · January 21, 2025, 8:55am

please check my above messages regarding this

Electr1 · January 21, 2025, 10:03am

When putting the device in burn mode it should be recognised on your PC, if not you may have possibly damaged the the SoC on the device, and may need after sales support.

in-sympathy · January 21, 2025, 11:02am

Well since it doesn’t get recognized and white LED is not on - I guess SoC is indeed damaged. Thanks, maybe I’ll try to get a new SoC and replace it

in-sympathy · February 27, 2025, 9:29am

Hi all. So I did get a new SoC and successfully replaced it. Now system boots with Android or Oowow - I can see it on the network after I flash eMMC via USB Burning Tool. Even more so - I can trigger WiFi hotspot in Oowow using this:
* Toggle [Easy Wi-Fi](https://docs.khadas.com/software/oowow/user-manual#easy-wi-fi) - short press **POWER** button

And it shows web interface:

And I don’t get network but do get two fast pulsing white LED pattern with Ubuntu.

BUT: regardless of the system I install there is absolutely no HDMI output.

Since I can really solder quite well - which components should I check and what reading should I get to fix HDMI? I believe it’s a hardware issue but no worries - I can handle that if someone from Khadas helps me out

And seems like really a lot of people are indeed having this no HDMI output problem - has anyone found a solution?

in-sympathy · February 27, 2025, 4:42pm

Burned some old Ubuntu onto the eMMC - it works from the terminal as you can see - updating all of the packages via ssh:

But still no HDMI - please help me figure this out. I mean if I need to directly reflash bios or replace any component - since I replaced a burned CPU - I’ll manage

I just need some help from one of the engineers or anyone who has managed to fix this issue

foxsquirrel · February 28, 2025, 1:24pm

If you don’t mind, please tell us how you managed to replace that by hand and get it running.

Also, if you smoked the soc the hdmi chip with no output is more than like smoked too. Pretty sure the hdmi is configured in the .dts and nothing is required in user side to get it up.

in-sympathy · March 1, 2025, 8:31pm

It’s not by hand - it’s by hot air
It’s not really that hard at all - just like any other BGA chip.

Anyways I do agree that original owner did smoke something in the HDMI sector as well as SoC. I just wonder what that might be, because I can solder quite well, but I suck at reading schematics as I’m a self-taught hobbyist in the field of electronics

foxsquirrel · March 2, 2025, 3:01pm

Just follow the hdmi connector, it will lead you to the hdmi chip. It takes a little bit of time to find where the connections are when the schematics are in pieces. Stare at it long enough and you will figure it out. Also, might look at the power management chip, that is one that could also be problematic since that sequences board start up.

in-sympathy · March 2, 2025, 7:50pm

Done.

Wasn’t that hard either to be honest