Monthly Archives: June 2012

Lenovo Ideapad Z565 – Resolving noisy fan issue and cooling problem

After a year of operation, I got increasingly disturbed by the high noise level of my Lenovo Ideapad Z565. Not sure whether it was that loud all the time, I started to pay more and more attention to the fan. The fan operation is controlled by the second button from the right in the row of system buttons in the upper right corner of the keyboard. The fan control button provides three options:

  • off – normal fan operation (default)
  • on – silent mode (touch the button)
  • blinking – “dust clean out” mode (touch the button for some seconds)

Even in silent mode, the fan got very noisy. When my system started to turn off without warning under heavy computational load, I observed that the air flow at the fan exit in the rear left corner of the laptop was a gentle breeze of hot air only. It soon became clear that it was by far too gentle to effectively get rid of the heat energy.

Solution

Finally I decided to have a closer look at the fan itself. The following documents how I accessed the fan of my Lenovo Ideapad Z565. Before dismantling the laptop’s cover, unplug all power supply, remove the battery and check with your warranty conditions! You will find detailed instructions in Lenovo’s Ideapad Z560/Z565 Hardware Maintenance Manual in section 1070 on page 41.

Lenovo Ideapad Z565 Backcover

The highlighted part of the backcover needs to be removed to access the fan of an Lenovo Ideapad Z565.

  1. Turn the laptop upside down and loosen the ten screws of the largest cover plate with a crosshead screwdriver. While the eight general screws can not be removed completely from the cover, put the two sunk-in screws in a safe place for later use.
  2. Remove the cover by gently pressing along its edges, starting from left to right.
  3. Identify the fan in the rear right corner and loosen the three crosshead screws holding the fan in place. Again, as these may be removed completely, put them in a safe place.
  4. Remove the fan from its position to expose the heat fins, that guide the fan air through the laptop chassis outside.
Lenovo Ideapad Z565 Fan Location

After removing the backcover, the fan is seen to be located in the rear right corner.

After removing the fan, the reason for the noisy fan and ineffective cooling soon became clear. A heat conductive copper construction redirects heat energy from the center part of the motherboard to the heat fins, that are placed between the fan and the air outlet of the cooling system. These heat fins are very narrow – too narrow as it was clear by now – and dirt and dust accumulated in the heat fins. These blocked in consequence the air flow and heat energy could not dissipate from the laptop.

Lenovo Ideapad Z565 Heat Fins

After passing the fan, the air leaves the laptop chassis through the heat fins (shown after cleaning).

Cleaning the heat fins and their surroundings with a vacuum cleaner at lowest power removes the dust effectively. Mounting the fan back at its original position with the three screws and fixing the back cover reassembles the laptop. It will be much more silent now and will operate more stable under heavy computational load.

Conclusion

The Lenovo Ideapad Z565’s air ventilation system is poor design. The final heat fins are the most narrow part of the pipeline. Dust and dirt accumulate on the way out and prevent a dissipation of the heat energy. A better filtering system at the air inlets would protect the system from pollution and would be easier accessible for maintenance at the same time. Moreover, I was surprised to learn that the noise is not caused by the fan itself but by the air passing through the heat fins.

spellmynumber.mnim.org – Wie merke ich mir die IBAN Nummer?

In diesem Artikel stellen wir eine Methode vor, um die Ziffernfolge einer IBAN Nummer in eine gut merkbare Buchstabenkombination umzuwandeln.

Das Problem

Die Internationale Bankkontonummer (besser bekannt unter dem Kürzel IBAN) wird mit Beginn 2014 die nationalen Kontonummern im europäischen Zahlungsraum ablösen. In den einzelnen betroffenen Ländern gibt es unterschiedliche Übergangsfristen. So werden in Österreich bereits am 1. Jänner 2013 die IBAN Kontonummern für Überweisungen und Lastschriften Pflicht sein (vgl. orf.at).

Kritik an der IBAN zielt vor allem auf die große Länge der neuen Kontonummern ab. Während die bisherigen nationalen Kontonummer zwölf Ziffern in der Regel nicht übersteigen, werden die IBAN Nummern je nach Nation zwischen 15 (Norwegen) und 31 Ziffern (Malta) lang sein (vgl. wikipedia). Jede IBAN beginnt mit einem zweistelligen Ländercode, der von Prüfziffern, dem Bankcode (vergleichbar mit der bisherigen Bankleitzahl) und der eigentlichen Kontonummer gefolgt wird. Entsprechend wird die Angabe des internationalen Bank-Codes BIC/SWIFT mit 1. Jänner 2016 nicht mehr nötig sein.

Die Lösung

Aber wie kann man sich jetzt die ewige Ziffernfolge einer IBAN Nummer merken? Es gibt verschiedene Techniken, lange Zahlenkolonnen in gedächtnisfreundliche Formen umzuwandeln. Hier wollen wir uns einer Methode bedienen, welche die Buchstaben einer Telefon- bzw. Handytastatur zu Hilfe nimmt. Jede und jeder kennt die Buchstabenbelegung der Handytasten vom SMS schreiben: die Ziffer 2 steht für die Buchstaben a, b und c. Die Ziffer 3 für d, e und f und so weiter.

Die Webseite spellmynumber.mnim.org versucht nun, in allen möglichen Buchstabenkombinationen, die einer Zahlenkombination entsprechen, sinnvolle Wörter in deutsch, englisch, französisch oder spanisch zu identifizieren.

Betrachten Sie die Zahl 43556 auf Ihrer Handytastatur. Sie entspricht zum Beispiel den sinnlosen Buchstabenfolgen gfkkm und hdlln, aber auch dem eingänglichen hallo. Mit ein wenig Glück enthält Ihre IBAN vergleichbare Entsprechungen!

Und so geht’s:

  1. Wandeln Sie nun Ihre Nummer auf der Seite http://spellmynumber.mnim.org in eine Wortkombination um. Die Ziffern 0 und 1 haben keine Buchstabenentsprechungen auf der Handytastatur und werden deshalb in Leerzeichen übersetzt.
  2. Merken Sie sich eine der errechneten Wort- bzw. Buchstabenkombinationen. Das gelingt viel einfacher als für die ursprüngliche Ziffernfolge.
  3. Tippen Sie nun die Wörter bzw. Buchstaben auf Ihrer Handytastatur. So erhalten sie die gesuchte Nummer.

Link zur Seite: http://spellmynumber.mnim.org

This article presents the method of http://spellmynumber.mnim.org, to convert IBAN international bank account numbers into sets of words, that may be remembered easily. This article is currently only available in German, the web page http://spellmynumber.mnim.org presents detailed english information.

SVN Repository Corruption – svn/db/current: End of file found

Version control systems such as subversion (short SVN) are great backup tools. But what if the SVN respository itself gets corrupted and no backup of the backup is available? This post demonstrates
how to recover from certain SVN repository corruptions.

For me, problems started when a svn commit aborted with the error message

PATH_TO_REPO/svn/db/current: End of file found

Examination of the file PATH_TO_REPO/svn/db/current revealed, that it was of zero size, vulgo empty. Looking out for solutions, I came across this post on the subversion user mailing list that describes how to restore this file.

First, navigate to the sub-directories of PATH_TO_REPO/svn/db/revs to learn about the youngest revision number of your subversion repository, e.g. the number of the latest revision. Each revision has a file entry in this path, named with the revision number. So the highest filename yields the youngest revision number.

Next, edit the file PATH_TO_REPO/svn/db/current by adding a single line

<youngest revision> zzzzz zzzzz

So for example if your youngest revision number was 5432, then the file should read

5432 zzzzz zzzzz

afterwards (the second and third colum are dummy entries).

Providing a transitional PATH_TO_REPO/svn/db/current enables us now to dump the entire SVN repository including all the information about revisions etc. into a backup file

svnadmin dump PATH_TO_REPO > svn.dump

If repository corruption affected only PATH_TO_REPO/svn/db/current, this step will succeed. However, if you are unlucky, you will encounter

* Dumped revision 5431.
svnadmin: Malformed file

or similar error messages. There might be plenty of reasons for this. This post here has some work-around, which ran me straight into another error

svnadmin: Can't set position pointer in file 'PATH_TO_REPO/svn/db/revs/0/5431': Invalid argument

It is important to recognize that the line just before svnadmin: Malformed file gives you the last revision that was dumped successfully. In my case, this meant that only the last revision was corrupted and I simply skipped that revision. Similarly, you might also skip corrupted revisions, see the -r argument of the svnadmin dump command,

svnadmin dump -r 0:5431 PATH_TO_REPO > svn_repo.dump

After having created a backup of the SVN repository successfully, move the old repository into some safe part,

mv PATH_TO_REPO /backup

and then create a new SVN repository at the original location

svnadmin create PATH_TO_REPO

Finally, load the backup into the repository (given that the repository was empty, as in our case, it will even have the same UUID afterwards).

svnadmin load PATH_TO_REPO < svn_repo.dump

Having arrived here, you will be able to use your SVN repository just as before.