Archive for the ‘Gadgets’ Category

Replacing iPhone 4 screen

Sunday, July 21st, 2013



I had the chance to help out with a neighbours iPhone 4 that had a broken screen. This gave me an excuse to pick up the pentalobe screwdriver to add to my collection of useful tools. The phone came to me in the state shown at the top of this post, the screen would light and you’d get lines as the image but the touch functions seems to be non-responsive. The phone was still working and you’d hear text message notifications and the like, I didn’t bother to plug it into a PC but I’m certain you could still sync it to a PC.



The pentalobe screwdriver is essential for opening up the iPhone. Those screws are really, really small. Disassembly is pretty straight forward, I made use of a pair of YouTube videos to help me out: the first video covers both tear down and rebuild; the second one is shorter and covers only the tear down.

Immediately after removing the back cover, I was amused to find the following warning:



If you’ve gone to the trouble of removing those darn screws, is a little plastic tab with a warning really going to deter you? At this point in the disassembly I started to get the feeling that I wasn’t the first person to have ventured inside of this phone. The plastic tab with the warning actually was busted off already, the battery wasn’t very tightly glued in and the water damage dot was entirely missing.

Once you’re inside the back cover a small Phillips screwdriver will handle almost all the screws. In my case the correct sized Phillips came along with the pentalobe. In the second video they talk about a single screw needing a small flat head jewellers screwdriver, this puzzled me until I got to that part of the disassembly. A rather ‘large’ small flat head is all I needed.



You can see the screw that needs this flat head in the center of the picture above, it’s looks like a big plus sign with a hole in the middle. The 3.5mm jack is visible in the picture.

To replace the screen you need to work your way through from the back of the phone to the front, this requires taking almost everything out of the phone. At this point it was clear that not only had someone been in this phone before, but that they had skipped over some of the reassembly steps. The screen should be fastened with 10 screws, this phone only had 7 and one of those that has a washer was missing the washer.

In my case, it turns out this phone had already had a replacement screen put in so there wasn’t any glue / stickiness holding the screen to the frame. Removing the two ribbon cables is a little fiddly, take your time and they’ll side out easily.



Re-installing the screen be very careful of the ribbon cables. It is very easy to get them pinched behind if they are not pulled through completely. If you don’t have them complete through they will not stretch far enough to connect to the motherboard. There is barely any slack in the ribbon cables, so if they are not routed correctly they simply won’t reach. This is one of those things that you can’t rush and taking your time when doing the disassembly (and taking pictures) can be a big time saver when re-assembling.

This was the 1st time I’d done this type of repair and it took me a little over 2 hours. I did fail to get one of the screws to install, it felt like the hole had been stripped. I’m not sure this was me or the previous repair job, but I still was frustrated to have it happen. Oh yeah, and work on a surface that will help you find those tiny little screws, even if you drop them – I worked on the floor with really good lighting and no clutter around me.

Unfortunately a bit over a week later I was back inside the same phone. Apparently while it looked and worked fine once I was done, over the next couple of days it started to exhibit ‘strange’ behaviour: fuzzy screen, non-working screen. These problems could be resolved by giving the phone a whack, but sometimes the whack caused it to be worse. Finally after one whack too many the screen went dark and that was it. [Please, don’t whack things to fix them!]

I was hopeful that it was simply a loose connector, but after reseating the various connectors I wasn’t able to bring it back to life. The owner took the phone to a repair shop that replaced the screen again and commented that some of the ‘knock off’ replacement parts had this type of problem.

In summary – I can’t claim that I really fixed it, but it was fun taking the phone apart and putting it back together again. I’ve got the tools I need now, and the experience. I was also pleased to find out that the 4 / 4s screens are fairly cheap, even locally. The screen for the 5 is much more expensive.

Fixing a fake USB flash drive

Wednesday, May 29th, 2013



A couple of years ago I picked up a conference give-away flash drive (4GB), which at the time seemed like a pretty nice freebie. The trouble was it only every liked to play nice with my Windows machine, Linux would refuse to mount it. The headline photo is the final product, I failed to take a before picture but the leather + snap case on this USB thumb drive was hideous anyway.

Turns out it was a fake, good thing it was free. Still in my typical fashion I didn’t want to just throw it away, heck I’m still carrying around the mysterious AMD 1GB key I got ages ago. So this bogus 4GB key sat in my work bag for a long while before I finally got to investigating it.

The very first thing I did was use the linux command lsusb, this helped me clue in that there was something wrong (fake) with the drive. I found a forum post that helped me get started down the right path. I got a copy of ChipGenius which told me the following:

Description: [I:]USB Mass Storage Device(Generic Flash Disk)

Device Type: Mass Storage Device

Protocal Version: USB 2.00
Current Speed: High Speed
Max Current: 100mA

USB Device ID: VID = 0011 PID = 7788
Serial Number: 874BE199

Device Vendor: Generic
Device Name: Mass Storage
Device Revision: 0103

Manufacturer: Generic
Product Model: Flash Disk
Product Revision: 8.00

Controller Vendor: Alcor Micro
Controller Part-Number: SC708(FC8708)/AU6987 - F/W EC23
Flash ID code: ADD5949A - Hynix H27UAG8T2BTR - 1CE/Single Channel [MLC-8K] -> Total Capacity = 2GB

So this felt like progress: it's 2GB and not 4GB as Windows seems to think. Still not bad for free. I then used my camera to get some close up shots of the naked circuit board to confirm the data that the ChipGenius tool dug out.




It was good to see that the values matched, this helped boost my confidence in the ChipGenius tool. I did find some references on the web claiming that sometimes ChipGenius is wrong, so it’s worth looking at the chips themselves.

Part of the output was also a link to a website, yet even with google translate the site left me guessing as to what I wanted to download – there were a lot of possible options. I choose one near the top “Series master, the Alcor MPtool AU6987T/6989 Yasukuni, production tools (2011.12.26.00)” as the title matches some of the data in the ChipGenius dump. In the end the stability of the site, language barrier and my inability to successfully download anything sent me off down other paths.

I then ended up searching on with the controller chip number (FC8708) I was able to find and download (with a bit of google translate help) a tool that recognized the drive. The best way to find this tool is searching it’s name: FC_MpTool_FC8308_FC8508_FC8406_04.02.01.

FC MpTool

The user interface was mysterious, but clicking on the drive letter started a reformat.. which resulted in a 2GB flash drive. This newly formatted drive was quite happy under Linux.

In terms of performance, I benchmarked copying 7 x ~300MB video files (total 1.9GB) to the stick, this reported ~4.7MB/sec. There were certainly bursty updates in file file progress dialog in Ubuntu. This isn’t great, but again it was free and it works under Linux. I also tried zeroing the entire drive ($ sudo dd if=/dev/zero of=/dev/sdc) which reported: 2095054848 bytes (2.1 GB) copied, 335.285 s, 6.2 MB/s – again, not great but good enough.

A bit of heat shrink tubing applied to cover up the bare circuit board and I’ve got a hack worthy USB key.

Installing a custom ROM on the SGH-I727R

Wednesday, October 31st, 2012

I’m a fan of running customized ROMs on my phone. There are three reasons: a) I like to tinker b) It provides added capability and longer currency for my phone c) I can get source for most of the code running on my phone. In this post I’ll talk about installing CyanogenMod 10, but a good part of this will be applicable to any after market ROM.

First I like to gather data about the state of the phone as it came to me. These details can all be found in the “About Phone” screen.

Android 2.3.5
baseband I727RUXKJ7

I’ve omitted my actual IMEI, but you’ll want to record that as it is possible to accidentally wipe it out on some phones. Fortunately as this phone came to me in the actual retail box, the sticker on the box matched the details here too.

The next step is to spend some time reading up on how to modify the firmware (ROM) and how to restore to stock. I’ve said this before, but it’s worth saying again: there is a lot of mis-information out there about how to go about this. Primarily this is because people don’t really understand what they are doing and simply provide instructions that seemed to work for them, voodoo magic included. An example is this youtube video I came across – well, it does give you confidence that it can be done, but there is no need to root your phone before installing a custom recovery.

If you’ve done any searching at all, you’ll have come across the XDA Forums, I do recommend signing up and reading through the relevant forums. Learn to search for answers, and share what you do know with folks who don’t. The newb starting guide is a good place to start. Also since my primary target is CyanogenMod, usually a good place to start is with their wiki – however, in this case it wasn’t.

The first step is to get a custom recovery image installed. ClockWorkMod (CWM) is the preferred solution for CyanogenMod and I’m familiar with it. To install it we need a tool that will talk to the download mode of our phone, and we need to get our phone into download mode. The tool I prefer to use is heimdall, it worked well with my i9000 and it’s also friendly to Linux. The other option is Odin (download link), a Windows only tool.

To enter download mode, the Rogers version is slightly different than the AT&T version – only volume down needs to be held with power (not volume up & volume down).

If you are successful you should be greeted by a screen as per above. Now assuming the USB cable is attached we can start the tool to send down the custom recovery image.

Sadly this is where I went off the rails a little, it turns out the version of heimdall (1.3.1) I had didn’t quite support the protocol being used by this phone. Upgrading to a newer version did fix the connection problem, but then it failed in another way I can only assume is also related to the protocol.

$ sudo ../Heimdall/heimdall/heimdall flash --recovery recovery.img
Heimdall v1.4 RC1

Copyright (c) 2010-2012, Benjamin Dobell, Glass Echidna

This software is provided free of charge. Copying and redistribution is

If you appreciate this software and you would like to support future
development please consider donating:

Initialising connection...
Detecting device...
Claiming interface...
Setting up interface...

Checking if protocol is initialised...
Protocol is initialised.

Beginning session...
Session begun.

In certain situations this device may take up to 2 minutes to respond.
Please be patient!

Releasing device interface...

And that was it, my phone was busted.

I did try several times to recover using heimdall and failed. So it was off to Windows to use the Odin tool to fix things.

I initially tried to simply install a version of CWM and then proceed from there, but I made a few mistakes. 1) I didn’t have the right version of CWM, I can’t explain this but I do admit I was thrashing a little here. 2) I did have some partial successes which probably left things in a somewhat dubious state causing my grief later when I was doing the right things (see log below).

E:Can't open /cache/recovery/log
E:Can't open /cache/recovery/log
E:Can't open /cache/recovery/last_log
E:Can't open /cache/recovery/last_log

The solution is to return to stock and start fresh. Thankfully Odin was quite happy to flash the stock version I got via XDA.

I did locate the correct version of CWM via the CM10 thread on XDA, I found the TeamChopsticks install guide quite helpful. Once I had the right mojo, things went smoothly.

Starting from stock
Install recovery via Odin, boot into recovery
Wipe & factory reset
Format /system
Flash CM10 nightly zip
Flash google apps zip (optional)

I like to have SSHD running on my phone along with rsync to allow for nightly backups to happen. Unfortunately CM10 isn’t yet shipping with dropbear pre-installed, and the CM7 version doesn’t seem to be happy anymore. I’ve switched to using the DropBear SSH Server app, the one downside is that it doesn’t auto-start on boot. I’ve been in touch with the author and this is on his future feature list.

A few notes on setting up DropBear SSH Server. The very first run will ask you to grant it super user privileges, it needs these so you need to say yes. Once the first screen is all green, you can test the server – the default root password is 42. Once you’ve verified it’s working, we want to fix the password under settings. I use keyed logins, and the app does support importing keys from files – but only one key per file. Once you’ve setup some keys, you can disable password logins entirely.

In CM10 you’ll probably want to enable USB Storage under Settings->Storage, then press menu to bring up ‘USB computer connection’ where you can opt in for USB storage (it is off by default).

Somewhere during the set of events I managed to end up in a state where the Radio version reported in About Phone was ‘unknown’. Phone calls worked fine, and I ran a couple of days without noticing this. I did later reboot into recovery and install a more up to date radio/modem firmware (I727RUXLF3). While I was in recovery I initiated a backup which I can return to if things get really messed up, this is handy as it is stored on the external SD card and is available even if I’m not somewhere with a computer and need to fix the phone.

CM10 has a new over the air (OTA) update system, I used it for the first time tonight to move to the latest nightly. Very slick, but there didn’t seem to be an option to back-up my existing state.

So aside from a few heart stopping moments where my brand new phone was totally fubar‘d, this was overall a pretty typical experience with a new device. Plenty of little details to figure out, a few new tools to install/configure/learn and the excitement of new hardware (and software). I’m really pleased with the i727, the screen still feels really big (but not too big). It’s fast and the battery life is very good. Google Now also recently added the ability to enter calendar events, resolving one of the few things I found it couldn’t do – and yes, Google Now is pretty darn cool.