Sunday, March 29, 2015

DIY of the day: replacing inflated capacitors on a Desktop PC Motherboard

Last week, i needed to replace inflated capacitors from a "dead" motherboard.
Inflated capacitors is a common cause of motherboards and electronic components "death", sometimes, replacing them will make these reborn.

Replacing inflated capacitors on Motherboard
3 new capacitors replacing the inflated ones
NB: don't forget to remove the 3.0V CR2032 Lithium Battery before performing any work on a motherboard.

This doesn't require any desoldering station or unsolder tape as i didn't have any of them available.

Required tools and materials:
  • soldering iron
  • soldering tin wire
  • small pliers

Usually when components are soldered to a PCB by human, the component wires are cut off after soldering:

 When things are done at industrial scale on a motherboard, the wires are cut extremely short:

So short that my "big" soldering iron couldn't transfer enough heat by contact to melt the very little amount of tin (Scale isn't respected, IRL, my soldering tip is bigger than the whole capacitor...):
Having no unsolder tape force to find an alternative, here is one i used:

Creating a droplet of melted tin (1) allows heat to be transferred to the component wire and melt the soldered tin (2). Prying and pulling the dead capacitor pops it out.

This is not the recommended way to repair a motherboard, but it works if you take your time and carefully follow the steps

update: I did it again!
Now with some photos...
The inflated capacitor

Adding two droplets of tin to better conduct heat

Removed capacitor

The new one is in place
 Testing : 
 It works!

Tuesday, March 24, 2015

Tip of the day: restoring WiFi settings after a factory reset

For some reason you may want to perform a clean install but don't want to waste all your spare time setting your complicated WiFi setup ?
Sadly you forgot to backup the WiFi settings (and google failed to re-sync them) but performed a Nandroid backup? 

 all the following steps can be performed directly on device, tested on Falcon running CM12 

story backgroung: after a buggy CM12 update and a failed rollback, my wifi settings were gone and google had synced the "blank" wpa_supplicant.conf file, i had no choice but trying to find a way to recover all the passphrases.

If you used TWRP, then things will be quite easy: 

  • Take your backup, 
  • Seek for 
  • Copy it to a dedicated folder and 
  • Rename it to data.tar.gz 

Assuming the backup is on your USB otg: 

  1. Open terminal and type: cd /storage/usbdisk/TWRP/backup/ 
  2. Make sure the file is there: ls 
  3. Untar: tar -xvzf data.tar.gz 
  4. After the unarchiving is completed you can search for ./misc/wifi/wpa_supplicant.conf 
  5. Rename the existant one (/data/misc/wifi/wpa_supplicant.conf to wpa_supplicant.conf.bak)
  6. Paste the new one there and 
  7. Give proper permissions/owner/group (-rw-rw----, owner 1000-system, group 1010-wifi). 

 Your WiFi settings are back and you can now focus on more interesting things.

If you want to discuss about this subject, meet us at