Kobo libra 2 VCOM

[nftstra]

I replaced my broken libra 2 screen with a new one, but it have a different vcom value, does anyone know how i can change the VCOM of my libra 2, the ifixit method doesnt seem to work for the libra 2 ?

Thank you!

[JSWolf]

This is from Google AI. It may or may not work. But it's not a problem if it doesn't work.

Step 1: Find the Target Screen Voltage

Every E-ink display is uniquely calibrated at the factory. The required voltage is written directly on the screen hardware.

• Open the device to view the mainboard and the display panel ribbon cable.
• Locate the printed sticker or a QR code on the E-ink display's flexible ribbon cable.
• Note the 3-digit decimal number (e.g., -2.81 or -1.23).
• Multiply this number by 1000 to get your VCOM value. For example, -2.81 becomes -2810.

Step 3: Calibrate the Value

If the recorded value doesn't match the hardware number from Step 1, apply the override:

• Open the Kobo eReader.conf file via a computer text editor (Notepad++ on Windows)
• Add your calculated value exactly as follows under the developer header:

ini

[DeveloperSettings]
VCOM=-2810

Save the file, eject your Kobo safely, and restart the device.

[PeterT]

@JSWolf I believe this info came fro m the ifixit web site and applies to the Kobo Libra Colour, Clara Colour, and Clara BW (both N365 and P365) models.

https://www.ifixit.com/Guide/How+to+...Display/170983

[JSWolf]

Originally Posted by PeterT

@JSWolf I believe this info came fro m the ifixit web site and applies to the Kobo Libra Colour, Clara Colour, and Clara BW (both N365 and P365) models.

https://www.ifixit.com/Guide/How+to+...Display/170983

The instructions on itifix say to use a vcom file to update. I'd try the kobo ereader.conf file. I can't hurt to try.

[nftstra]

Originally Posted by JSWolf

This is from Google AI. It may or may not work. But it's not a problem if it doesn't work.

Step 1: Find the Target Screen Voltage

Every E-ink display is uniquely calibrated at the factory. The required voltage is written directly on the screen hardware.

• Open the device to view the mainboard and the display panel ribbon cable.
• Locate the printed sticker or a QR code on the E-ink display's flexible ribbon cable.
• Note the 3-digit decimal number (e.g., -2.81 or -1.23).
• Multiply this number by 1000 to get your VCOM value. For example, -2.81 becomes -2810.

Step 3: Calibrate the Value

If the recorded value doesn't match the hardware number from Step 1, apply the override:

• Open the Kobo eReader.conf file via a computer text editor (Notepad++ on Windows)
• Add your calculated value exactly as follows under the developer header:

ini

[DeveloperSettings]
VCOM=-2810

Save the file, eject your Kobo safely, and restart the device.

thank you

I tried this as well but it didnt solve the problem the device keep running on the original vcom which is in my case off by a lot so its hurting the screen, the last thing gpt suggest is to change the hex files on the sd card

so im going to look how i can carefully remove the sd card and clone it on a new one and see what happens

[JSWolf]

Originally Posted by nftstra

thank you

I tried this as well but it didnt solve the problem the device keep running on the original vcom which is in my case off by a lot so its hurting the screen, the last thing gpt suggest is to change the hex files on the sd card

so im going to look how i can carefully remove the sd card and clone it on a new one and see what happens

Good luck. If you do manage to do this, please let us know what it is you did. Thanks.

[Waldy]

Originally Posted by nftstra

I tried this as well but it didnt solve the problem the device keep running on the original vcom which is in my case off by a lot so its hurting the screen, the last thing gpt suggest is to change the hex files on the sd card

so im going to look how i can carefully remove the sd card and clone it on a new one and see what happens

It is not necessary to remove the SD card from the device to change the vcom values.
Enable network access (SSH, FTP, Telnet) on your Kobo Libra 2 using NickelMenu, or enable SSH manually. Use any SSH, FTP, or Telnet client, such as PuTTY.
Copy the unpartitioned 24 MB area (sectors 0–49151) from the device to the root of the device using dd:

dd if=/dev/mmcblk0 of=/mnt/onboard/0-49151_24MB.img bs=1M count=24

Check the vcom value of your new screen (for example, mine is -1.67 mV).
Take the value -167 (in my case) and convert it using a Decimal to Hexadecimal converter.
For -167, I got FF59.
Connect the Kobo Libra 2 to your PC and open the file 0-49151_24MB.img using the HxD editor.
Go to offset 80030 (Ctrg + G).
At offset 80030, change the values ​​in columns 07 and 08 to FF59 (yours will be different) and save the file.
Safely disconnect the Kobo from the PC and connect via the network (SSH, FTP, Telnet).
Copy the modified 0-49151_24MB.img to the device using dd.

dd if=/mnt/onboard/0-49151_24MB.img of=/dev/mmcblk0

Once the process is complete, reboot the device.
Here is a short video, it might be helpful to someone.


If necessary, we handle a "non-native" SD card image in the same way.
Open the SD card image in a hex editor, locate offset 80030, change the hex values ​​in columns 07 and 08 to the ones calculated using a "Decimal to Hexadecimal converter," and save the file.

I’m no expert, so please let me know if there are any errors or if there’s a different way to do it.
This was discussed here at some point, but the topic didn't generate much interest.

[DNSB]

I took at look at several of my Kobo images and I had either what looked like a valid VCom value or a 00 00 at that address. Just for the heck of it, I grabbed the 24MB blocks from 4 of my Kobo collection and the VCom numbers were correct.

It would appear that if someone needs to replace their µSD card, they could hex edit the image to insert the correct VCom value before writing their µSD card. Quite a few people are already doing this to install their serial number at 0X200.