Aura H2O Changing VCOM value after screen replacement?

lambstone · 01-14-2026, 08:21 PM

Is there a way to update the VCOM values? I am experiencing the grainy issues on my Aura H2O Gen 1 replacement screen since the original screen had a value of -1.35 and the replacement has -2.34 which I think is too big of a difference.

I've done some research on this matter and apparently there might be a way to adjust this by hex editing the SD card image but I can't seem to find the VCOM values this way. I know what the VCOM values are stored on the sd card as flashing a different SD image results in different screen issues which seems to suggest that there is a value stored directly on the sd card somewhere and not hardcoded into the device.

Unfortunately, the vendor for my replacement screen hasn't been of much help.

mrmikey · 01-15-2026, 05:23 AM

I don't have a Glo but could it be the same procedure as this?:
https://www.ifixit.com/Guide/How+to+...Display/170983

DNSB · 01-15-2026, 07:09 PM

As far as I know that information and procedure only applies to the Libra Colour and Clara BW & Colour. I have not tested (adding a file called VCOM with the new VCOM value but on a Sage, you see the firmware information without the VCOM value and on a Clara HD, you don't have a firmware information entry in Device information.

JSWolf · 01-15-2026, 07:13 PM

Quote:

Originally Posted by DNSB

As far as I know that information and procedure only applies to the Libra Colour and Clara BW & Colour. I have not tested (adding a file called VCOM with the new VCOM value but on a Sage, you see the firmware information without the VCOM value and on a Clara HD, you don't have a firmware information entry in Device information.

Is this something that could be patched to be enabled on the newer firmware?

mrmikey · 01-15-2026, 07:43 PM

Quote:

As far as I know that information and procedure only applies to the Libra Colour and Clara BW & Colour.

I wasn't sure as I don't have a Glo to look at but I took a chance and posted it in case :-(

lambstone · Yesterday, 01:38 AM

Yeah, really couldn't find any information. I'm fairly confident this can be fixed either via hex edit or a patch, unfortunately I do not have the skills to do this from scratch.

01-14-2026, 08:21 PM	#1
lambstone Enthusiast Posts: 39 Karma: 10 Join Date: Apr 2014 Device: Kobo Glo	Changing VCOM value after screen replacement? Is there a way to update the VCOM values? I am experiencing the grainy issues on my Aura H2O Gen 1 replacement screen since the original screen had a value of -1.35 and the replacement has -2.34 which I think is too big of a difference. I've done some research on this matter and apparently there might be a way to adjust this by hex editing the SD card image but I can't seem to find the VCOM values this way. I know what the VCOM values are stored on the sd card as flashing a different SD image results in different screen issues which seems to suggest that there is a value stored directly on the sd card somewhere and not hardcoded into the device. Unfortunately, the vendor for my replacement screen hasn't been of much help.

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01-15-2026, 05:23 AM	#2
mrmikey Member Posts: 14 Karma: 10 Join Date: Dec 2012 Device: Kobo Clara HD	I don't have a Glo but could it be the same procedure as this?: https://www.ifixit.com/Guide/How+to+...Display/170983

01-15-2026, 07:09 PM	#3
DNSB Bibliophagist Posts: 49,593 Karma: 174632684 Join Date: Jul 2010 Location: Vancouver Device: Kobo Sage, Libra Colour, Lenovo M8 FHD, Paperwhite 4, Tolino epos	As far as I know that information and procedure only applies to the Libra Colour and Clara BW & Colour. I have not tested (adding a file called VCOM with the new VCOM value but on a Sage, you see the firmware information without the VCOM value and on a Clara HD, you don't have a firmware information entry in Device information.

Yesterday, 01:38 AM	#6
lambstone Enthusiast Posts: 39 Karma: 10 Join Date: Apr 2014 Device: Kobo Glo	Yeah, really couldn't find any information. I'm fairly confident this can be fixed either via hex edit or a patch, unfortunately I do not have the skills to do this from scratch.