Screen gradually going grey when idle (after replacement)

Kobotomised · 12-11-2025, 04:06 PM

Hi all,

I picked up 2 Kobo Clara 2E and a Clara BW, all with broken screens. I have replaced them all, the 2 Clara 2E's with screens from AliExpress and the Clara BW with a screen from iFixit. I disconnected the battery first and reconnected it last for all 3.

One of the Clara 2E is fine. The other, and the Clara BW appear more or less fine, but lack contrast compared to the "good" 2E. If refreshed they are fine but gradually fade. Some of the words when reading are randomly not as black as the others. If left on the home or settings page for 30+ sec the background gradually turns light grey in a TV static/speckled type pattern, not uniform. The Sleeping screen is not as contrasty as it should be but the background remains clear. The Powered Off screen is not as black as it should be.

I have played with the alignment of the display ribbon cables, cleaned up the connectors with 99.9% IPA, made sure there is no remnant of conformal coating in the connector. On the BW I have amended the vcom setting to match the value on the ribbon cable (x1000). I am not able to adjust the 2E but the variance is not huge - and the "good" 2E works fine despite a similar variance.

I have applied the latest software updates and restarted multiple times.

Have I got 2 bad screens or is there something I am doing wrong?

neclepsio · 12-12-2025, 06:06 AM

Edit: I missed that you amended the vcom per https://www.ifixit.com/Guide/How+to+...Display/170983

Quoth · 12-12-2025, 06:40 AM

It's not like replacing CRT, plasma, LCD, DLP, OLED. The eink are very variable. I replaced one once. Never again.

IMO, if an eink panel is damaged the best value is a new ereader.

Kobotomised · 12-12-2025, 01:59 PM

I've done many replacements and all successful until now. iFixit have asked me to tweak the vcom setting +80 and -150 to see what happens. They seem willing to replace.

I just want to know what is going on really, for troubleshooting and certainty.

I pulled my big boy pants on and did 3 Kindle screen replacements today, a 7th gen, 8th gen and 11th gen. The 7 & 8 went perfectly. The 11 was a screen from a unit with a motherboard fault. That one also has done pretty much the same thing. Fine on refresh, fine on the lock screen, but when idle it gradually darkens. It feels like a massive coincidence that 3 panels from 3 completely different sources go this way in 2 days. They're all USB type C powered, newer devices but the actual panels are different, of course. 2 variants of Carta 1200, 1 Carta 1300.

Kobotomised · 12-12-2025, 02:03 PM

I've tried cleaning and reseating the LED, battery and digitiser cables as well but as expected those make no difference at all. The display cable maybe changes the rate of grey-fill very slightly, if I remove it and put it back slightly more or less inserted. There's not a lot of wiggle room for that connector.

Quoth · 12-13-2025, 09:56 AM

There is massive variability on eink panels. Some replacements will be fine and others won't.

Kobotomised · 12-17-2025, 04:42 AM

Update on this - iFixit asked me to return the panel for inspection after tweaking the vcom didn't work. A bigger number made the problem instant, going lower delayed it but didn't fix it.

I've put the Kindle 11 stuff to one side as it's all old stuff there's not much I can do unless I get another one.

The Clara 2E screen I got from AliExpress, the seller asked for install photos and said it all looks OK. They said they test every panel and they are 99% sure it's a problem with the display port on the Clara. I cleaned it again with a soft toothbrush and 99% IPA but no difference. I will look for another 2E I guess, or a Tolino Shine 4. They're so rare...I am not sure I want to take a new one apart, or a working/used one, to "prove" a £45 AliExpress screen.

I will at least update on the iFixit one...

Waldy · 12-17-2025, 01:52 PM

I'm almost certain your screens are perfectly fine. The problem lies in the motherboards removed from devices with broken screens. A broken screen often damages the motherboard, resulting in the problem you're describing.
This is especially true with the Clara BW.
And forget about VCOM and Waveform.
With a working screen and a non-original motherboard, you won't notice any issues, despite the different VCOM and Waveform values.
Trust me.

12-11-2025, 04:06 PM	#1
Kobotomised Member Posts: 16 Karma: 10 Join Date: Sep 2025 Device: Kobo Libra 2	Screen gradually going grey when idle (after replacement) Hi all, I picked up 2 Kobo Clara 2E and a Clara BW, all with broken screens. I have replaced them all, the 2 Clara 2E's with screens from AliExpress and the Clara BW with a screen from iFixit. I disconnected the battery first and reconnected it last for all 3. One of the Clara 2E is fine. The other, and the Clara BW appear more or less fine, but lack contrast compared to the "good" 2E. If refreshed they are fine but gradually fade. Some of the words when reading are randomly not as black as the others. If left on the home or settings page for 30+ sec the background gradually turns light grey in a TV static/speckled type pattern, not uniform. The Sleeping screen is not as contrasty as it should be but the background remains clear. The Powered Off screen is not as black as it should be. I have played with the alignment of the display ribbon cables, cleaned up the connectors with 99.9% IPA, made sure there is no remnant of conformal coating in the connector. On the BW I have amended the vcom setting to match the value on the ribbon cable (x1000). I am not able to adjust the 2E but the variance is not huge - and the "good" 2E works fine despite a similar variance. I have applied the latest software updates and restarted multiple times. Have I got 2 bad screens or is there something I am doing wrong?

12-12-2025, 06:06 AM	#2
neclepsio Member Posts: 23 Karma: 10 Join Date: Oct 2024 Device: Kobo Libra Colour	Edit: I missed that you amended the vcom per https://www.ifixit.com/Guide/How+to+...Display/170983 Last edited by neclepsio; 12-12-2025 at 06:20 AM.

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12-12-2025, 06:40 AM	#3
Quoth Still reading Posts: 15,259 Karma: 112712961 Join Date: Jun 2017 Location: Ireland Device: All 4 Kinds: epub eink, Kindle, android eink, NxtPaper	It's not like replacing CRT, plasma, LCD, DLP, OLED. The eink are very variable. I replaced one once. Never again. IMO, if an eink panel is damaged the best value is a new ereader.

12-12-2025, 01:59 PM	#4
Kobotomised Member Posts: 16 Karma: 10 Join Date: Sep 2025 Device: Kobo Libra 2	I've done many replacements and all successful until now. iFixit have asked me to tweak the vcom setting +80 and -150 to see what happens. They seem willing to replace. I just want to know what is going on really, for troubleshooting and certainty. I pulled my big boy pants on and did 3 Kindle screen replacements today, a 7th gen, 8th gen and 11th gen. The 7 & 8 went perfectly. The 11 was a screen from a unit with a motherboard fault. That one also has done pretty much the same thing. Fine on refresh, fine on the lock screen, but when idle it gradually darkens. It feels like a massive coincidence that 3 panels from 3 completely different sources go this way in 2 days. They're all USB type C powered, newer devices but the actual panels are different, of course. 2 variants of Carta 1200, 1 Carta 1300.

12-12-2025, 02:03 PM	#5
Kobotomised Member Posts: 16 Karma: 10 Join Date: Sep 2025 Device: Kobo Libra 2	I've tried cleaning and reseating the LED, battery and digitiser cables as well but as expected those make no difference at all. The display cable maybe changes the rate of grey-fill very slightly, if I remove it and put it back slightly more or less inserted. There's not a lot of wiggle room for that connector.

12-13-2025, 09:56 AM	#6
Quoth Still reading Posts: 15,259 Karma: 112712961 Join Date: Jun 2017 Location: Ireland Device: All 4 Kinds: epub eink, Kindle, android eink, NxtPaper	There is massive variability on eink panels. Some replacements will be fine and others won't.

12-17-2025, 04:42 AM	#7
Kobotomised Member Posts: 16 Karma: 10 Join Date: Sep 2025 Device: Kobo Libra 2	Update on this - iFixit asked me to return the panel for inspection after tweaking the vcom didn't work. A bigger number made the problem instant, going lower delayed it but didn't fix it. I've put the Kindle 11 stuff to one side as it's all old stuff there's not much I can do unless I get another one. The Clara 2E screen I got from AliExpress, the seller asked for install photos and said it all looks OK. They said they test every panel and they are 99% sure it's a problem with the display port on the Clara. I cleaned it again with a soft toothbrush and 99% IPA but no difference. I will look for another 2E I guess, or a Tolino Shine 4. They're so rare...I am not sure I want to take a new one apart, or a working/used one, to "prove" a £45 AliExpress screen. I will at least update on the iFixit one...

12-17-2025, 01:52 PM	#8
Waldy Groupie Posts: 152 Karma: 3339 Join Date: Jun 2017 Device: Tolino,Kobo,Onyx,Kindle,BN,PB,Likebook...	I'm almost certain your screens are perfectly fine. The problem lies in the motherboards removed from devices with broken screens. A broken screen often damages the motherboard, resulting in the problem you're describing. This is especially true with the Clara BW. And forget about VCOM and Waveform. With a working screen and a non-original motherboard, you won't notice any issues, despite the different VCOM and Waveform values. Trust me.