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iPhone Diode Mode Measurements – LogiWiki

The creator of this page has done a great job at creating high resolution pictures and iphone diode mode measurements.  These include Macbook and iPad diode mode measurements.  Diode mode readings are essential for micro soldering because without schematics, there is no easy way to diagnose and repair these devices.

Until now, ZXW was the only software that contained vast amounts of iphone diode mode measurements for these devices.  It seems as though LogiWiki has more readings now.  It’s definitely not as easy to find the diode mode readings in LogiWiki as it is in ZXW, but just use the search function on the left sidebar and you should be able to find whatever you need.

Sample from LogiWiki

At this point, I would say that this site is an essential part of iPhone, iPad, and Macbook logic board repair.  Check out the page if you haven’t already.

Without diode mode readings, the only way to repair logic boards is to buy another similar logic board and compare diode mode readings from the known good logic board.  This is a time consuming and often arduous task.  Usually, if it gets to this point, then I tend to just shy away from these jobs.

For instance, Samsung devices are notorious for lack of schematics, which make them way more time consuming to repair.  These days, I barely take on Samsung devices for repair because of added time and the low success rate.

The great thing about LogiWiki is that the site is built by repair technicians helping each other.  Diode mode measurements aren’t the end all, be all, but they definitely help expedite the repair process, especially for devices where schematics aren’t widely available.

Hopefully, together, we can expand on the amount of diode mode measurements for devices where schematics aren’t available, so that we can repair more devices and keep them out of the landfills.

iPhone 11 No Backlight After DIY Screen Repair

We’ve been seeing more and more of these iPhone 11 no backlights lately.  Basically, the backlight goes out after a screen repair mainly because the battery is not disconnected during the repair.  It’s been happening since the iPhone 6s and it seems like it’s still happening with the latest iPhone versions with LCD screens.  iPhones with OLED screens aren’t affected by backlight issues because the technology is different with these screens.  iPhone with OLED screens include the iPhone X, XS, XS Max, 11 Pro and 11 Pro Max.  Although, even those phones have after market LCD screens now.

Anyways, good news is that we can repair iPhone 11 backlight issues.  What makes it a little more challenging is that the iPhone 11 is the first phone with a sandwiched logic board that uses an LCD screen.


The best way to identify an iPhone 11 no backlight problem is to shine a bright light in the middle of the screen, then look for some sort of image.  You should be able to see an icon or the apple logo or maybe a battery charging symbol, similar to this:


In the picture above, when a bright light is shined on the screen, you can see a faint apple logo, which tells us that the lcd is working, but the backlight is not.

In order to fix the backlight on an iPhone 11, we need to take the logic board out of the frame, partially remove the shield that covers the backlight components on the logic board, then take off and replace the two backlight resistors (aka backlight filters) that are blown.

The pictures above show the location of the backlight resistors.  There are two of them.  Both resistors will need to be replaced.  Since we don’t know the exact values of the resistors, we can just use the iphone 8 backlight resistors as they should be comparable.

The only thing to note about this repair is to be careful removing the shield that covers these backlight resistors.  Since the logic board is sandwiched, any heat applied to the logic board will most likely separate the two logic boards, then you’ll have other problems on your hand.  The best way to get access to these backlight resistors is to use some sharp micro cutters and snip away the shield without using heat.  You can watch a video of our iPhone 11 backlight repair on youtube.

How to Setup and Install ZXW Tools v3.x

ZXW Tools is the most essential piece of software for logic board repair because it contains schematics for most iPhones and point-to-point connection drawings.  It also contains component level information, images of components, diode mode readings, and component orientation on the logic board.  If you’re doing logic board repair, then you’ll want to use this software to do your job.  Here is how you install it:

Step 1

Download the latest version of the software:

Step 2

Extract the contents of the file to a directory on your desktop.

Step 3

Run the executable to start the software.blank

(If you run into any issues with the executable, then you’ll need to disable any anti-virus software that you have running.  Unfortunately, there is no way around this.)

Step 4

You’ll need a license to access the schematics, so you can buy a 1-year license through our online store here.

Step 5

After you purchase the license, we’ll send you a Serial number and Password via email.  You’ll need these two things to create an account and activate your license.  You’ll need to create an account at the ZXW website here:

Step 6

After you create an account at the ZXW website, then you’ll need to click on Authorization Code Renewal link on the left and then enter your Serial number and password that you just received. blank

From there, if you click on The Personal Data link, then you should see that your 1-year license has been activated and the page will also show you the expiration date.  That’s it!

iPhone 11 No Power Logic Board Repair

We just had our first case of repairing a no power iPhone 11.  The history of the phone is that the customer dropped it, then the phone stopped working.  The repair shop replaced the screen and there was no change.


After opening the phone up, we didn’t notice anything unusual with the logic board.  Upon further testing, we didn’t notice any shorted power lines like vdd_main or pp1v8 or pp3v0.  Since we didn’t see anything unusual, we decided to separate the two logic boards.  Yes, the iPhone 11 has a sandwiched logic board with an interposer board just like the iPhone X, iPhone XS, iPhone XS Max, iPhone 11 Pro, and iPhone 11 Pro Max.  The sandwiched logic boards are always a little dicey to work with, especially if there were torn pads on the logic board.


Upon separating the two logic boards, we noticed that there were two chips that were cracked.  Since there are no detailed schematics available for these iPhones yet, we were uncertain about the exact function of these two chips, but we were able to make some good guesses based on past logic board repair with older iPhones.


We determined that one of the chips was the big audio chip and the other was a some sort of power chip.  After replacing both of these chips from a donor board, we were tasked with the challenging task of resoldering the two separated logic boards back together.


After four attempts, we were able to get everything working once again.

Some of the challenges that we faced were the fact that the backlight dimmed out with the ear speaker flex disconnected.  This was probably the biggest grief for us because we also missed a cracked backlight coil, which both contributed to the backlight not working.  After replacing the broken backlight coil, we thought that we had fixed the problem, especially after getting 20v at both anode pins, but we were trolled by the ear speaker flex being disconnected.

The second challenge was sandwiching the two logic boards back together.  We had to do it a total of 4 times, mainly because we didn’t tin the pads well enough and we didn’t apply enough pressure to the two logic boards after heating them up.  It was mainly at the two ends of the logic boards that we were having the most problems because they tend to warp a little and bend upwards and away from the interposer board.

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Anyways, I’m happy to say that after four attempts, we were able to get everything working on the iPhone 11 logic board, so I think that we can comfortably say that we’re qualified to work on these logic boards now.

If you’re interested in sending in your iPhone 11 logic board for repair, then please request a quote here.