Showing posts with label maintenance. Show all posts
Showing posts with label maintenance. Show all posts

Sunday, April 21, 2013

Feeling the Heat

I have been meaning to give my old Samsung X60s a service for a while; ever since I originally set the machine up as a combined home security system and media centre in fact. The system had always been a bit noisy and this had become much worse of late. Today I booted the machine up in order to listen to some music and after running for a few minutes it powered off without warning. Switching the machine on again resulted in the same outcome.

I pulled the machine out of it's dock and booted it up a third time, this time I simply switched to another virtual console just to quickly check the syslog file. There I found the following message:

Apr 21 13:56:20 media-centre kernel: [ 372.609087] Critical temperature reached (97 C), shutting down.

So, I had to bite the bullet and take apart the machine to try and clean out the dust. I thought I'd take some pictures to document the process:

Monday, August 8, 2011

26 Screws Later...

A couple of weeks ago a friend of mine asked if I could take a look at his laptop, a Samsung M55. The machine had become infected with a virus and, after exhausting all other possibilities, he had backed up all his data and attempted to re-install Windows. The machine ships with Windows XP Media Centre Edition, one of the only instances of this particular build of XP I've ever seen!

Once had access to the machine, I discovered the Windows installation was partially complete. It appeared to have completed the initial stage of the install where the hard disk is formatted and the installer is copied over. The laptop booted into the second stage where the remaining OS files are copied over from the hard disk and the system is configured.

I decided to start the installation process from the beginning, so I inserted the restore disk supplied with the machine and rebooted. This is when I began to notice two things about the machine: first, the optical drive was extremely "clunky" and slow, secondly, the machine's fans appeared to be continually running at full speed. I pressed on with the installation, only to have the machine spontaneously power off part way through the first stage!

I guessed from the noisy fans that the system had overheated, so I made the decision to open up the chassis and clean inside using some compressed air. I soon regretted this decision, as I had to remove no less than 26 screws before I could prise the top of the chassis from the bottom! It was so convoluted that I had to remove the display in order to gain access to the last couple of screws.

Once inside, I could see the problem: the grill covering exhaust port on the left hand side of the machine was completely clogged with dust, as well as the fan responsible for venting hot air out through it:


A few sprays of compressed air later and the insides began to look far more healthy:


I painstakingly put the machine back together (no "spare" screws left over afterwards either, phew!) and powered it on to begin the installation process again. Unfortunately, this time the optical drive was slow at reading the restore disc it took an entire evening to complete the initial stage of the installation, which was followed by the installer being unable to read the disc after the machine rebooted. I tried various methods of getting it to recognise the disc in the drive, to no avail, so I resorted to using my own external DVD burner to finally get the OS installed!

After some really annoying issues, I had finally got my friend's laptop back in working order, albeit with a very unreliable optical drive. As you can imagine, I was very relieved!

While reflecting back on the task, I formulated these after thoughts:
  • 26 Screws!!! - I'm not sure what Samsung where thinking when they designed the laptop. To give you an idea of how complicated the damn thing was to take apart, take a look at the service manual I found online (PDF format). The cynic in me believes that they simply wanted to make it so difficult for an end user to maintain the system themselves, that they'd be forced to use one of their service centres to do so. Paying a premium to do so, of course. I'm a great believer in being able to repair and replace components in one's hardware, or at the very least be able to perform some basic maintenace (clearing out dust, for example). Sure, the vast majority of people will be inclined to take their machine's to a "qualified" technician to have repairs carried out, but for those of us that want to maintain their own kit (and even enjoy it), please don't make it near impossible to do so.

  • While on the topic of maintenance, there were some ribbon cables that were extremely difficult to work with. Instead of having the cables terminated with a plastic connector to facilitate connecting to and disconnecting from the motherboard, those present in the M55 looked like this:


    As you can see, they are terminated with some metal contacts and the cable needs to be held in place while the connector on the board is clipped into the locked position:


    As you can imagine, this was incredibly frustrating to work with! I hope I don't have to work with connectors like this again.

  • It is interesting how Samsung have designed the cooling system for the laptop; neither the CPU, nor GPU have their own fans, instead a heat-pipe connects both to a heat-sink which the single, small, fan cools by venting air across it and out through the exhaust port. I've not opened up too many laptops, so I'm unsure how common this practice is, but I was intrigued by it.


  • Optical drives are usually the first thing to die on a machine due to having many moving parts, which are regularly exposed to an dirty external environment. When will we do away with them? I rarely use mine on any of my machines and only when (re)installing an operating system or burning the odd CD/DVD if someone needs some files and there is no USB thumb drive available. The newer MacBook Air models are no longer supplied with an OS X installation DVD, instead they have a bootable USB thumb drive containing the OS.

Despite a rather stressful experience taking the machine apart, I was pleased with the end results, as was my friend. I also gained some valuable experience maintaining Samsung laptops, which I can use on my own Samsung X60 machine.

Tuesday, April 27, 2010

Ubuntu MySQL Upgrade Issue

I recently had to assist a friend who is hosting sites on an Ubuntu VPS; he found himself unable to connect to local MySQL instance as root.
Obviously, my first suggestion was to simply reset the password using the --skip-grant-tables trick that's well documented elsewhere online. However, attempting to stop the MySQL instance using the command /etc/init.d/mysql stop was not successful. So, after backing up the /var/lib/mysql directory, I began to research the issue a bit further:

  1. Unable to use the init.d script to stop MySQL, I manually stopped the process: killall mysqld

  2. Started the MySQL daemon, ignoring the permissions/grant tables: /usr/bin/mysqld_safe --skip-grant-tables &

  3. Reset the root user's password: UPDATE mysql.user SET Password=PASSWORD('new-password-here') WHERE User='root';

  4. Ran mysqlcheck to look for any corrupted tables (especially in the "mysql" database containing the accounts and permissions) and noticed that errors were being thrown in relation to the "information_schema" database: mysqlcheck --all-databases

  5. Attempted a repair of the "information_schema" database: mysqlcheck --repair information_schema

  6. Ran mysqlcheck again against the "information_schema" database; errors were still produced by the same tables as before.

  7. Restarted mysqld and noticed errors being output in relation to the "debian-sys-maint" user.


This particular error was what helped to identify the root cause of the issue. The server had recently been updated using the apt-get tool and this had included an update to MySQL. Trawling the web unearthed a bug filed on the Ubuntu project bug tracker that suggested that the post-upgrade scripts had not been executed. There is a dedicated MySQL account that exists on a Debian-based system specifically for this (and other DB maintenance) tasks: debian-sys-maint
The credentials for this user can be found in the file /etc/mysql/debian.cnf and should already be present in the MySQL database itself; allowing the system to perform maintenance tasks. Realising this user must be missing from the system, I set about recreating the user:

  1. Logged into MySQL as root and, using the credentials specified in /etc/mysql/debian.cnf, created the "debian-sys-maint" user: GRANT ALL ON *.* TO 'debian-sys-maint'@'localhost' IDENTIFIED BY '';

  2. Now restarting MySQL generated different error messages: Cannot proceed because system tables used by Event Scheduler were found damaged at server start

  3. Knowing that the MySQL package installed on the system had been upgraded recently (and judging by the number of people in similar situations), I forced the execution of the mysql upgrade scripts: mysql_upgrade -u root -p --verbose --force


After these steps were carried out, restarting the MySQL instance occurred without any errors being produced as well as it being possible to authenticate to the system as "root".