Aura H2O Aura H2O (1st gen.) screen repair howto

[hatteras]

This is my very first post ever. On any forum. I hope I'm not stepping on anyones toes...

About a year ago I agreed to fix the broken screen of a friends Koko H2O. By that time I had successfully repaired an Icarus8 and several smartphone screens and I thought the most tedious part would be to wait for the new screen to arrive from China... Well I made my bet without knowing anything about infrared touch screen technology and the wonders of water-proof assembly with double-sided tape. To change the screen was easy, but even after a good dozen of tries I couldn't get the touch screen to work properly and for a device with just one button that is a no go.

Eventually I gave up and felt bad about it ever since, until I got another broken H2O on ebay for parts to start over. This time it worked out.

I thought I could post a little step-by-step in case anyone needs to change a broken screen, not wanting to go through the whole learning experience. I am sure there are other ways to do it and comments and corrections are welcome. I am only documenting what I have done.


overview

Spoiler:

I hope these drawings will help you understand what I'm talking about. The Aura H2O is quiet the stack of layers. For the touch screen to work pcb and light guide have to be lined up perfectly, but they are not connected directly to each other. That is what makes changing the screen so difficult.

Tools and materials
• An old credit card-shaped plastic card cut in half lengths-wise. The classic guitar pick is useful too. Avoid metal. It's too easy to damage plastic parts.
• Some kind of heat-gun to soften the adhesive. Not strictly necessary, but makes it much easier. (<10€ on ebay)
• WD40 and paper-towels to clean off the adhesive (if you know about a better solvent I'd like to know...)
• IPA to clean the surfaces before putting on new adhesive
• Small Phillips screw-driver
• A razor blade or an exacto knife
• Your new screen of course. Always check the part number on the ribbon cable of your old screen. Mine was ED068OG1 (about 30€ on aliexpress)
• One sheet of A4-sized 3M 300LSE double-sided adhesive (5€ on ebay / aliex)

part 1 : taking it apart

Spoiler:

1. Gently heat up the front cover all around to soften the adhesive. Use one hand to feel the temperature as you go. Before the front cover gets too hot to touch it with your bare hand switch off your heat gun.
2. Try to find an opening between front and back cover with your thumb nail or plastic card. Make your first opening all around the outer edge of your reader. You only need to go 3-4 mm deep to split front and back cover. It won't come off yet. That's normal and will only happen in the next step. You might get stuck as the adhesive cools down again, so add some heat.


3. Heat the front cover up again. Go around the outer edge for a second time. This time you will need to reach further inside. You need to push in between front cover and light guide (aka bezel, but I'll stick with light guide) until you reach the bump of the light guide. If all goes well you end up with the front cover completely removed.


4. Now it's time to remove the light guide from the screen. You need to work from the inside out, sliding your tool between light guide and screen. Start at the bottom of the screen were the adhesive strip is the largest. Apply heat if necessary, but be careful the light guide is fragile. Try to lift it evenly on all sides, keeping it horizontal. There are very small plastic pins on the four corners that you don't want to break off. Once you are done you'll have the bare screen in front of you.
5. Take out the screw in each of the four corners and lift up the screen / pcb assembly. Lift the top first and drag the bottom behind to work your way around the usb connector.


6. Turn the extracted part around to face the pcb. disconnect battery, screen and front light. the battery disconnects by gently lifting the back side of the connector. The screen is the largest connector. You need to lift the plastic squeezer at the back of the connector, the you can pull out the ribbon cable. The front light connector is just under it and works like the screen connector. You can change the screen without disconnecting the battery, but I find it much easier to clean everything after completely removing the pcb.
7. There are 6 screws holding the pcb to the aluminum back plate. Unscrew them and take off the pcb.


8. By now only the (broken) screen is attach to the aluminum back plate. Once again this is done with double sided tape. One strip in each corner (in the picture the screen is already taken off, but you can see the position of the tape). Separate screen and plate by sliding the credit card between them and pushing it against the tape. Heat can help soften the adhesive (do NOT heat the battery !). Be careful not to cut yourself at the edge of the screen, especially if it's shattered.


9. Congratulations, you have successfully put everything to bits...! I'd like to tell you the hard part is done, but noooo. Time to clean all the adhesive : back plate, inside of the front cover, light guide inside and outside and the rim of the back cover (not in the pictures, but needs cleaning none the less...). The inside of the light guide is easy. Usually you can peel off the whole tape in one piece. The rest is messy. Soak the adhesive in WD40, scrape it off with a credit card. Wipe the surface off with some more WD40 until there are no traces of adhesive left. Now you need to clean the WD40 with IPA or simply lots soap and water. Dry thoroughly afterwards. The cleaning is really important. For the most part, double sided tape is really all that's holding your reader together, especially the light guide for the touch screen. Alignment and thickness of the different layers matter. In my experience the only way to get it done is to clean and start with fresh adhesive.

[frostschutz]

why people insist on separating the front bezel + infrared guide is beyond me

it's supposed to stay together

yes there is a lot of glue all around, but even so, you can pry the front bezel (including the IR layer) off using no tools other than your fingernails. start in the top corner, it comes off. the water-seal glue is sufficiently soft/flexible at room temperature, no heat guns required neither. there's a youtube vid where someone stabs in with a guitar pick, and even says you should be harsh with it, too much... patient and gentle does the trick

or well, at least that's how it worked for me (old post)

https://www.mobileread.com/forums/sh...66#post2998466

front bezel + IR stayed as one part. re-gluing the IR to the bezel is not something I would look forward to

in the end I only had to remove some glue lumps from the water seal, not re-glue anything myself

obviously not water proof anymore but I doubt it ever was - for my other H2O the front bezel was lifted up in one corner when snapping it into a protective case so that's not waterproof either despite never opened all the way

[hatteras]

@frostschutz : Truth is, I would have liked to find your post when I started this. Unfortunately I didn't. I don't remember how exactly, but I ended up with a new screen and a non-working touch screen.
In trying to fix that by understanding how the touch screen worked I got probably as close as you can to the work at the actual assembly line...

At one point I wanted to be able see the alignment pins of the light guide going into the pcb. (see 14.) Only way to do this was to separate front bezel and infrared guide... That's the only technical reason I can offer.

Yes, it's long and messy, but I still recommend this procedure. Works every time, you get perfect alignment, no gaps, no bumps... That was especially important since I made the repair for someone else.

part 2 : back together again

Spoiler:

10. Now it's time to put everything back together. I made a cutting guide (h2o adhesive frames.zip : make sure to print the pdf at 100%) to get all the necessary shapes of adhesive out of a single A4-sized sheet. You might get away with strips of tape of different sizes. But after trying that first, I think it is a weaker connection and may not last long. My initial goal was to make the reader water-proof again, which only works with uninterrupted tape. Rumors about additional nano particle treatment kept me from drowning my newly-repaired H2O (1st gen.). Maybe someone knows more about that ?
11. Print out the cutting guide, glue it on a sheet of A4-sized 3M 300LSE double-sided adhesive with glue stick or spray glue and cut it out with a blade or an exacto knife. I made everything a little undersized to have some wiggle-room, but that is to make it easier to put the tape correctly on the parts, you still need to cut them precisely on the line. If you don't want to ruin your sheet of adhesive on your first try, make a test run with paper. Cut everything out and see for yourself. That helped me a lot.


12. Now that you have all the adhesive ready, start by putting it on the aluminum back plate. Before pulling off the protection from the other side of the tape put your new screen on the plate to get a feel for it. Pay close attention to how you are planning to route the two ribbon cables. Both need to go to the back side of the aluminum. What works best for me to position the new screen, is to put in the two bottom corners while the rest of the screen is still at an angle. When the cables are where they belong push the rest of the screen in like a door, aiming for the two upper corners.


13. Now put the small adhesive frame on the inside of the light guide and the bigger frame on the inside of the front cover. You should have a gap of about half a millimeter around all the edges to avoid sticky tape sticking out from inside the casing later. Always verify the tape by holding it over the part to get a feel for its position before peeling of the protective paper. Then just pull off a small part of one outside corner at the bottom and stick it on. If it's a small corner you might still be able to reposition it if you have to. If you are satisfied with the one corner pull away the protective paper from the whole bottom side, cutting it if it's in your way (paper only, not the adhesive !). Now, applying tension to the tape and aiming for the other bottom corner, you can stick the tape on. Continue the same way for the left and right side and finish with the top side.


14. Put the pcb to the back of the aluminum plate, carefully threading screen-, front light- and battery cables through their openings. Hold it in place only very loosely with two screws (the pcb still needs to be able to slide a tiny bit on the aluminum for the aliment in the next step). Connect battery, front light and screen. You can turn your reader on now to check the screen, but turn it back off afterwards.


15. Pull off the protective tape from your new screen if there is any and position the light frame over it. You might have noticed that the light guide has a tiny plastic pin in each corner. They go into four corresponding holes in the pcb. If they are not in yet, push them in gently. Turn everything around and put it screen-down on a flat, forgiving surface (ex. card board on table). If the pins popped out of their holes push them back in. you can still wiggle the pcb to find the right position. You have the right position when all four pins stay in without you pushing. Now tighten the two screws on the pcb and put in the four others. Double check the pins. The screen and the pcb are aligned now.


16. Time to glue the light guide down, the most sensitive part of this operation. Just like for the screen itself, I suggest you make always a dry run first. Put the two bottom pins into their respective holes in the pcb, but keep the light guide angled away from the screen. Not so much as to break the pins, but enough as to keep the adhesive away from the screen. You can do that with just your index finger in the middle of the bottom edge of the light guide if you put the reader on the table. Then gently let the light guide down making sure the upper pins fall into place. Rub around the surface of the light guide to make the tape sick. Even without the housing you should be able switch the H2O on and the touch screen should work. The sketch pad in the beta features is a good place to check out the touch screen.
17. Almost done now, two more steps : Put your reader into its back cover and put the screws in the four corners.


18. You need to glue the front cover on the rest of the housing. It helps to create a 90 degree corner on the table by clamping down two straight pieces of wood or even just two heavy books. If you push one corner of your reader into this, it gives you a guide to put the front cover in the correct position. Once I'm done with all the sticky tape I put the reader screen-down on a flat, hard surface and weight it down over night to make the tape stick even better, but I don't know if this is strictly necessary.
19. Voilà !! Your Aura H2O has a brand new screen. But sadly I must say you should probably keep it away from water from now on. As I sad, I never checked for water-proofness.

conclusions

Spoiler:

After all the time I had spend fixing this one machine I was sure about the repeatability of the procedure. I thought I should make use of it and got myself a whole batch of Aura H2O's with broken screens. I wanted to fix them, do something against electronic waste and maybe even make a little money.

I hope you will forgive me for saying out loud that I'm selling them on eBay. I have done five, so this really works ! I have to to tell you though, that even after ordering directly from China I will be lucky to break even. No money to be made by fixing cheap electronics... (No, that does not really come as a surprise).

I'm glad however I took the time to write down this little howto. Hope it helps someone.
Don't hesitate to comment.

further reading

Spoiler:

One last thing : the infrared touch screen is quiet interesting. Definitely longer-lasting than its capacitive / resistive counterparts. Kobo seems to have abandoned it tough...



After digging around the internet for quiet some time I found a research paper about Neonode, the company selling the ir touchscreen technology, their technical support page and two of their patents. I'll leave you the links if you're interested. This information eventually made my repairs possible.
• https://ijcsmc.com/docs/papers/Septe...V2I9201321.pdf
• Mechanical Integration - zForce AIR® Touch Sensor User's Guide : https://support.neonode.com/docs/dis...al+Integration
• Touch screen for mobile telephone - Google Patents : https://patents.google.com/patent/US7880732B2/en
• Light-based touch screen - Google Patents : https://patents.google.com/patent/US8339379B2/en

[Markismus]

@hatteras Nice posts! Would you know what wavelength the IR LEDs use. I couldn't find it in the docs from further reader.

I have already fixed the screen of my Kobo Aura H2O. But the touchscreen had a problem with a column on the left. It turned out to be a missing infrared diode (IR LED side SMD). Still trying to pin down what wavelength the photodiode receivers use. Apparently, 850 and 940nm .

Unfortunately, the size of the diodes has changed over the years. My old pocketbook and Kobo Aura HD use a larger IR LED, otherwise I could have soldered that one onto my H2O....probably, still going to try that.

EDIT: It's working again!

[hatteras]

@Markismus good for you !

Sorry, didn't have any info on the ir diodes. I managed to see them glow under the camera of my phone back when I was still trying to confirm that the touch screen actually uses infrared light, if that is of any help.

I found this post on 840nm vs. 940nm https://www.eevblog.com/forum/projec...gth-of-ir-led/ :
"840nm and 940nm are common wavelength values used for IR remote controls. It is easy to differentiate between both, because you can see 840nm slightly glowing in the dark, but 940nm is virtually invisible.
You can verify the LED is active by using a digital camera: The LED should be visible as a white or purple spot."
Same here : https://ellipsesecurity.com/2018/05/...r-illuminator/


But I did not actually build a test circuit to try that out. You were using older, larger leds for your repair ? Did I get that right ? Took a picture by any chance ?

[Markismus]

Thanks! That is a practical approach! I'll use it to check them next time.

I used the size of the ones linked to on AliExpress. The ones in the H2O are a bit smaller. We're talking half a mm or somehting.
The ereader is still not as responsive as I would like. So I'll probably open it up and check the other IR LEDs: I'll snap a photo.

[Quoth]

The IR sensors and the plastic have a quite broad response. I'd think slightly more 940mm IR will pass black plastic than 840nm. It's likely only the dispersion angle of the integral lens on the LED has much effect.
Either wavelength works with most IR receivers in VCRs, TVs, Set-boxes etc. Unlike the photo-sensors in touch screens and rotary encoders the IR remote control receivers have a filter to block visible light as part of the plastic encapsulation and use 36 KHz to 40 kHz modulation. The IR receiver has the photo-diode or photo-transistor, a 38 KHz amplifier / filter (to reject 50Hz, 60Hz, 100Hz and 120Hz lighting flicker and sunlight), then a level detector and logic level output. The IR touch screens likely have plain photo-diodes / transistors and the controller IC multiplexed ADC followed by processing. That IC will multiplex the transmit LEDs too. It's likely that it scans slowly with narrrow pulses to save power and then switches to a fast accurate mode when the initial touch is detected. You can play with the sketch application to see that this is very probable.
Also I've designed low power electronics, originally in late 1980s. It was standard to intermittently pulse on the receiver till a signal was detected (battery powered receivers of IR, ultrasonic or RF remote signals).

I've used ANY sort of electronic camera without a professional IR blocking filter to check IR LEDs. Even in 1970s the vidicon tubes in otherwise "solid state" security cameras had no filter to block IR. This was so "heat" lamps with black filters could be used as covert flood lights at night. Some used two 230V halogen spot lamps wiired in series.

Professional video cameras and still cameras have IR and UV blocking filters to avoid false colour. I've never seen any evidence of either in phone cameras, my camcorder or fuji still camera as all those will respond to my UV Led for security marker ink and any IR remote handset.
Some IR handsets use IRDA, a high speed protocol that used to be on some PDAs, phones and laptops. The set-boxes that those use won't work with most universal IR remotes.

[Markismus]

@FrustratedReader And also thanks for the added text to your post!

[frostschutz]

I also replaced a H2O display today. ( it's not my first time opening H2O but my first time actually doing the display replacement ).

The broken H2O was a lucky find on Ebay ( under 10€, basically paid shipping only ).

Before ordering a new display, I verified it worked perfectly fine otherwise, including the touch screen function. Well, I'd probably have ordered a display even if the touch didn't work...

The new display was 25€ from aliexpress so the whole unit cost me 35€ ( plus my own sweat and tears during the replacement process ).

Anyway. I'm lazy. So, I did it all without taking the PCB off. Didn't replace the old glue pads either, well I would've but none to be found in the house and couldn't wait. Anyway.

It works. The display quality is even perfect, absolutely zero issues (so far).

There was a bit of panic with "water on the screen" message because the front bezel was not aligned perfectly on first try reassembly (it has those 4 little notches that actually have to sink into the PCB itself to make it work - first time I ever notice that and there is no way to see it with the backplate on).

Your pictures were very helpful, particularly the exact position of the glue pads under the display. Even so I didn't quite manage to take the broken display off in one piece... preserved the front light LEDs of the old display (LED is a glue stripe that peels of, if you do it carefully), so I have some (miniscule) hope of repair if one of the now three operational H2Os ever suffer a frontlight failure.

I will try to upload some pictures later.

And yeah I'm also totally cutting a hole into the back of this one for easy internal SD card access.

[frostschutz]

Pictures...

Originally Posted by frostschutz

There was a bit of panic with "water on the screen" message because the front bezel was not aligned perfectly on first try reassembly (it has those 4 little notches that actually have to sink into the PCB itself to make it work - first time I ever notice that and there is no way to see it with the backplate on).

pictures with circles are the front bezel going into the PCB... so if that's not aligned proper, touch does not work. so many little details in this thing...

there were a bunch of books stored on the reader, roughly 200... not to mention email address and other personal info. make sure to clean your stuff out before you send it back, you never know what people do with it. well, factory reset it is...

[hatteras]

Ok, you got me convinced. Next time I won't separate ir bezel and front cover... Nothing beats laziness to make things simpler !



Still one thing I didn't get. How do you put the screws back in when the front cover is blocking them ? I think that is why I ended up ripping the front cover off : being able to see that the notches are in their holes AND putting the screws back in.

[frostschutz]

not sure if I understand your screws question.

the front cover/bezel is not screwed on at all (that's why you can take it off).

the PCB is screwed to the metal frame and the metal frame is screwed to the back cover.

all other parts (display and front bezel and IR fins) are held together by glue and glue alone. other kobo models (before waterproof/glue came along) just used clamps in the plastic frame itself (the kind as breaks off when you open it)

first picture here shows the device just before screwing it back onto the back cover.

I have to be a careful with mine since I didn't renew the glue pads for the display at all (they were not included in the package, unfortunately) so it probably doesn't stick very well anymore.

I considered buying another fintie case where the H2O just snaps in, but they seem to be out of stock indefinitely ... well, it is an older model

edit: oooh, I think maybe you were confused by my pictures that show how the front bezel hooks into the PCB? those were taken with out the back cover. that's just to understand what is happening / for illustration, not how you actually assemble it. you have to screw the unit into the back cover then put the front bezel on it (and can't see whether it went in properly, but it helps to know that this could be a problem, so wiggle things a bit until touch works). this device can only be opened from the front, order cannot change

[Markismus]

@Frostschutz Nice work and pictures! What kind of glue did you use?

Yesterday evening I replaced the battery and reglued the front bezel. (Forgot to snap a picture of the LED's.) It seemed perfect, but I now find that I have some trouble with the upper menu in koreader. So I probably misaligned or dropped some glue in the wrong place. It's going to be a bother to get it opened and cleaned again.

[frostschutz]

Originally Posted by Markismus

@Frostschutz Nice work and pictures! What kind of glue did you use?

None... whatever was in there is still in there.

I really should go back and tape the display down properly (so it won't slam into one of the corners if the reader is ever dropped). Well, I assume that what would happen if the display doesn't stick to its backplate proper. Not testing that. I just didn't have any suitable tape at hand.

Originally Posted by Markismus

Yesterday evening I replaced the battery and reglued the front bezel.

I don't reglue the front bezel at all... I just don't separate IR fins and bezel (stays as one part) and it sticks well enough using the glue that was already there - sticks to the display in particular, getting it off the display without cracking it can be a challenge, particularly at the bottom where there's a really wide glue strip - as seen in the first picture of my first post here

Of course, not waterproof anymore but that's a tall order anyway.

Edit: oh, I actually use a bit of clear spellotape on the back to seal the sd-card-hole but I guess most people don't cut a hole there, anyway

[désirante]

Originally Posted by frostschutz

why people insist on separating the front bezel + infrared guide is beyond me

it's supposed to stay together

yes there is a lot of glue all around, but even so, you can pry the front bezel (including the IR layer) off using no tools other than your fingernails. start in the top corner, it comes off. the water-seal glue is sufficiently soft/flexible at room temperature, no heat guns required neither. there's a youtube vid where someone stabs in with a guitar pick, and even says you should be harsh with it, too much... patient and gentle does the trick

or well, at least that's how it worked for me (old post)

https://www.mobileread.com/forums/sh...66#post2998466

front bezel + IR stayed as one part. re-gluing the IR to the bezel is not something I would look forward to

in the end I only had to remove some glue lumps from the water seal, not re-glue anything myself

obviously not water proof anymore but I doubt it ever was - for my other H2O the front bezel was lifted up in one corner when snapping it into a protective case so that's not waterproof either despite never opened all the way

Just to say that this philosophy worked perfectly for me when I replaced my Kobo H2O first gen (2014) screen this week, with one slight modification: I used a combination of fingernail (initially) plus a spudger (latterly) to separate the bezel & ir guide combo from the case back, but I also needed to actually get underneath the bezel from the inside (i.e. between the e-ink screen and the inner bezel rim) using a credit card before I could fully detach the bezel/ir guide assembly from the case.

Once that was done, the rest was plain sailing: 4 screws off, then battery detached, then e-ink screen ribbon cable and front light ribbon cable detached, then 6 screws off, then removal of the (in my case shattered) screen [go very carefully when you get to the four locations of the double-sided tape], then replace with new screen & front light, then reverse the rest of the process. I never bothered with replacing either the double-sided tape nor any of the glue and everything went back together without difficulty. No hot-air gun needed either.

The overall appearance after replacement depends of course on the quality of the replacement screen (for me an ED068OG1): I paid little more than $20 on Ali Express, and received a very glossy screen but with a matte screen protector already applied over the top of the front light. I'm absolutely fine with that but it may be possible to pay more and get a true matte screen like the original - ymmv.