Tuesday, December 20, 2011

EVO 3D Digitizer Install

Sorry for the long delay between this post and Part 1 / Part 2 of the broken EVO 3D digitizer saga. I was tempted to leave the story unfinished forever because of the comic below entitled "Wisdom of the Ancients:"

But I wouldn't do that to you.

A quick side note. If you don't read XKCD, you really should. It is one of the most consistently brilliant webcomics I have ever had the pleasure of reading. So when you are done here, go read and subscribe to the RSS. And be sure to read the mouseover text for each comic. You will not regret it.

Back to the phone. From this point forward, I have decided to be consistent on how I refer to the part I am replacing. The phrase "touch screen" is too ambiguous for my taste. There are two parts that make up the touch screen. The touch part is built onto the back of the glass face of the phone. This is the digitizer. The screen part is behind the digitizer and is just a normal LCD screen. If you crack the glass on your phone, but the picture still shows up ok, you broke the digitizer. If the picture is messed up, you broke the screen. I'm glad we had this little talk. I feel better now.

The digitizer I ordered arrived from Amazon. It has a plastic film on the face of the glass to protect it. However, the back side of the digitizer is not glass. It is plastic. Easily scratched plastic. This digitizer arrived with several scratches on the non-glass side. Not cool. It also does not come with replacement adhesive for holding it in place. The description says, "Adhesive is on the back of flex, just peel off and apply," but apparently this only refers to a small rectangle of adhesive on the cable, not the adhesive that holds the digitizer in place. 

I will continue with the replacement anyway for a couple reasons. First, it will prove whether this part is causing my problem or not. Second, even if there are some scratches, if it fixes the problem my phone will be usable again. Since I am suffering from a severe case of smartphone withdrawal, I will install this semi-defective part and leave an unflatteringly truthful review on Amazon.

I now have a replacement digitizer and a video on how to take apart most of the phone. I follow the video and begin the disassembly. It goes well. Soon I have a pile of tiny parts where there was once a phone. I reach the end of the video, but it leaves me with the digitizer and screen still firmly entrenched in the front part of the case. It gives some vague advice about using heat and prying everything apart like on other HTC phones, but that is not so helpful to someone who hasn't done this to other phones.

It does point me in the right direction though. Armed with their somewhat nebulous comment, I go back into research mode. The HTC EVO 4G looks similar to the 3D, and it has been on the market much longer. Maybe there is a better guide for removing the digitizer on that phone. It turns out that there is.

So. I now have a very good photo tutorial on how to remove a similar digitizer. The following photos are blatantly stolen from ifixit.com in case they decide to take down the tutorial. Links are provided giving them full credit, so hopefully they will not be too upset.

The video leaves off at the point that corresponds to Step 20 on the EVO 4G teardown guide. This step has you start applying heat (but not too much heat) to the outside edge of the digitizer. The digitizer is held in place by adhesive. It is some form of very thin double-sided tape. Once you heat up an edge, you can start prying the digitizer from the front part of the case. The following few steps go through heating and prying each edge of the digitizer. At this point on the EVO 4G, you would be done. Remove the digitizer and stick the new one in place.

The EVO 3D is slightly different. Once you have battled the adhesive and removed your old digitizer, you will discover that the cable runs between the screen and the case. To get the cable out (and insert the new one) you have to remove the screen as well. This is not good news. In removing the digitizer on my phone, I destroyed it. The plastic film on the back side of the glass that does the actual sensing work was damaged along the top edge. This is no big deal, since I am replacing this part. However, now I have to remove the screen. My screen works fine. I have no replacement for it. I do not want to hurt it by removing it roughly.

Having no other choice, I continue with Step 33 on removing the screen. The screen is held on by two strips of adhesive, one on each of the long sides of the screen. (Left and Right when holding the phone normally - i.e. portrait, not landscape.) At this point, I get to apply heat directly to the LCD. This makes me a bit nervous, but I have come this far already. Going slowly, I apply heat and pry.. heat more and pry... and continue until it comes loose. Then I repeat for the other side. The only mistake I made was probably using too little heat to start with. Things went better with a little more heat.

I must note at this point that I am using a heat gun with pretty good temperature control. The lowest setting is 200F and that is what I used throughout. If you are using a heat gun without temperature control, I would worry more about damaging something. Just saying.

At this point, the screen is removed. It even looks to be undamaged. Now I get to re-assemble. Having no other option, I reused the old adhesive to hold both the screen and the new digitizer in place. I would not recommend reusing the adhesive for the digitizer. It attracts dust and lint like a magnet. Especially if you try to clean your fingerprints off of the screen. The fingerprints which you will inevitably get over everything as you try to pry things apart. Anything caught on the inner edge of the adhesive will show up around the outer edge of the display once it is all back together. You are much better off removing the old adhesive, cleaning everything up, and then applying new adhesive. Assembly is reverse of removal, but much easier. When putting it back together, there is no prying or heating.

Everything is back together. Now comes the moment of truth. Is it better? Is the problem solved, or did you break something going through this process?


Success! The screen is unharmed. Yay! The digitizer is responsive again. My phone works! Now to deal with the scratches... Which means getting another digitizer and repeating the entire process. At least this time I will have a better idea of what I am doing. Yay...  :-/

I feel that I must apologize for the lack of pictures in this post. My phone serves as my digital camera. I couldn't figure out a way to use it to take a picture of itself disassembled. I tried to describe what I encountered using words alone, but if it is terribly unclear, I refer you to the XKCD comic linked at the beginning of this post.

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