Clara BW Screen turns grainy shortly after refresh

diogenes3575 · 05-13-2025, 02:42 PM

Hi all,

I just replaced the screen on my Kobo Clara BW and have been getting a weird issue. When the screen refreshes it looks fine, but after about thirty seconds the screen goes all grainy (see pictures). I've updated the VCOM to match the new screen and as far as I can tell the motherboard is connected to the screen correctly. I didn't see any damage on the leads as I was reassembling the kobo, though I'm not sure if that dent in the battery has something to do with it. Any ideas on what might be going on?

DNSB · 05-13-2025, 02:57 PM

What vcom value did you enter in the vcom file before copying it to the root of your Kobo's exposed storage? I am doubtful that the vcom number would have that effect on your Clara BW's display since once the black and white particle are moved into place, they should be pretty much static but have not played with the effect of changes so it's possible.

diogenes3575 · 05-13-2025, 03:11 PM

I entered -2590 (1000x-2.59 as shown on the third photo above). When I first booted it after the screen replacement I hadn't changed the VCOM yet, but even after fixing the VCOM the issue persists.

DNSB · 05-13-2025, 03:36 PM

Quote:

Originally Posted by diogenes3575

I entered -2590 (1000x-2.59 as shown on the third photo above). When I first booted it after the screen replacement I hadn't changed the VCOM yet, but even after fixing the VCOM the issue persists.

What does the vcom value in Settings => Device Information => Firmware Information show? Again, I suspect this is not a vcom issue since it occurs on a static screen. What happens if you do a sleep or shutdown with the cover showing?

Waldy · 05-13-2025, 03:56 PM

With such a picture, the vcom value has nothing to do with it. Look here, is it cleaned well there:

diogenes3575 · 05-13-2025, 04:49 PM

Quote:

Originally Posted by Waldy

With such a picture, the vcom value has nothing to do with it. Look here, is it cleaned well there:

I thought I had pulled all the plastic out of the connector slot, should I just go in and remove all the plastic in the vicinity?

diogenes3575 · 05-13-2025, 04:51 PM

Quote:

Originally Posted by DNSB

What does the vcom value in Settings => Device Information => Firmware Information show? Again, I suspect this is not a vcom issue since it occurs on a static screen. What happens if you do a sleep or shutdown with the cover showing?

I would have to double check once I get home but as I remember it this morning it was the correct value (I was on my way out the door when I checked so maybe scrambled the digits in my haste)

PHughes · 05-14-2025, 08:39 AM

Quote:

Originally Posted by diogenes3575

I thought I had pulled all the plastic out of the connector slot, should I just go in and remove all the plastic in the vicinity?

I would disconnect it, then be sure everything is clean, then reconnect.

JSWolf · 05-15-2025, 03:57 PM

How did you get on cleaning the connector?

diogenes3575 · 05-22-2025, 07:41 PM

Quote:

Originally Posted by JSWolf

How did you get on cleaning the connector?

The connector seemed clean, the only damage to any connector I could see was maybe a small scratch on the backlight connector, but I haven't had any backlight issues. As best I can tell, I damaged the battery when removing it and there's some issue with power discharge happening at the wrong time. The fading to graininess only happens when the ereader is on, not when sleeping or off. That's a total guess though, open to any other solutions you might have.

Waldy · Today, 01:57 AM

Quote:

Originally Posted by diogenes3575

The connector seemed clean, the only damage to any connector I could see was maybe a small scratch on the backlight connector, but I haven't had any backlight issues. As best I can tell, I damaged the battery when removing it and there's some issue with power discharge happening at the wrong time. The fading to graininess only happens when the ereader is on, not when sleeping or off. That's a total guess though, open to any other solutions you might have.

I can send you KoboRoot.tgz with these values:
520_VSH019_HS3401_ED060KHEC1_VD1405-FOH_TC
But first save your original wf_lut.gz file and send it to me so I can try it myself first. Or so you can get your file back. You can save it using the KOReader file manager. The file is located at data/init_bin/wf_lut.gz.

Or you can get the image like this: https://www.mobileread.com/forums/sh...&postcount=576
Only for clara BW/Colour/Libra Colour I use this command:

Code:

head -c $((512 * $(cat /sys/block/mmcblk0/mmcblk0p11/start) )) /dev/mmcblk0 > /mnt/onboard/mmcblk0.rawimg

wf_lut.gz is in waveform.img.
https://ibb.co/ZzNMbD6y

05-13-2025, 02:42 PM	#1
diogenes3575 Junior Member Posts: 8 Karma: 10 Join Date: Apr 2025 Device: Kobo Libra 2	Screen turns grainy shortly after refresh Hi all, I just replaced the screen on my Kobo Clara BW and have been getting a weird issue. When the screen refreshes it looks fine, but after about thirty seconds the screen goes all grainy (see pictures). I've updated the VCOM to match the new screen and as far as I can tell the motherboard is connected to the screen correctly. I didn't see any damage on the leads as I was reassembling the kobo, though I'm not sure if that dent in the battery has something to do with it. Any ideas on what might be going on? Attached Thumbnails

05-13-2025, 02:57 PM	#2
DNSB Bibliophagist Posts: 45,037 Karma: 168808719 Join Date: Jul 2010 Location: Vancouver Device: Kobo Sage, Libra Colour, Lenovo M8 FHD, Paperwhite 4, Tolino epos	What vcom value did you enter in the vcom file before copying it to the root of your Kobo's exposed storage? I am doubtful that the vcom number would have that effect on your Clara BW's display since once the black and white particle are moved into place, they should be pretty much static but have not played with the effect of changes so it's possible. Last edited by DNSB; 05-13-2025 at 03:01 PM.

05-13-2025, 03:56 PM	#5
Waldy Connoisseur Posts: 99 Karma: 3277 Join Date: Jun 2017 Device: Kobo,Tolino,BN,PB,Kindle,Likebook,Inkbook	With such a picture, the vcom value has nothing to do with it. Look here, is it cleaned well there: Attached Thumbnails

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05-13-2025, 03:11 PM	#3
diogenes3575 Junior Member Posts: 8 Karma: 10 Join Date: Apr 2025 Device: Kobo Libra 2	I entered -2590 (1000x-2.59 as shown on the third photo above). When I first booted it after the screen replacement I hadn't changed the VCOM yet, but even after fixing the VCOM the issue persists.

05-15-2025, 03:57 PM	#9
JSWolf Resident Curmudgeon Posts: 79,249 Karma: 145488788 Join Date: Nov 2006 Location: Roslindale, Massachusetts Device: Kobo Libra 2, Kobo Aura H2O, PRS-650, PRS-T1, nook STR, PW3	How did you get on cleaning the connector?