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Les problèmes d'alimentation des PC portables ne sont pas rares, mais il n'est pas toujours évident de savoir si c'est la batterie, l'adaptateur secteur (le “chargeur”) ou l'ordinateur lui-même qui en est la cause. Voici l'aide dont vous avez besoin !

Résumé

Si votre ordinateur portable ne s'allume pas, ne se recharge pas, ou s'éteint à nouveau immédiatement ou de façon aléatoire, il n'est pas toujours évident de savoir si le problème vient de l'ordinateur, de la batterie ou de l'adaptateur secteur. Les tests simples décrits ici devraient vous permettre de déterminer ce qui doit être réparé ou remplacé.

Sécurité

Avant de poursuivre, veuillez noter ceci :

• Une batterie de remplacement inadaptée peut être dangereuse
• Les adaptateurs secteur de remplacement de mauvaise qualité peuvent être dangereux
• Tenter d'ouvrir et de réparer un adaptateur secteur peut être dangereux.
• (Ces points sont développés plus en détail dans l’article ci-dessous).

Diagnostic

Une alimentation ou une batterie défectueuse est un problème relativement courant sur les ordinateurs portables. Votre premier objectif doit être d'essayer de déterminer si le problème vient bien de là et laquelle des deux est défectueuse.

La plupart des ordinateurs portables peuvent souvent fonctionner sans batterie, tant qu'ils sont branchés sur le secteur. Retirez la batterie et voyez si l'ordinateur portable fonctionne en étant donc uniquement branché sur le secteur. Si c'est le cas, la batterie est très certainement morte ou en fin de vie.

A contrario, vérifiez si l'ordinateur portable fonctionne uniquement avec la batterie. Si c'est le cas, le problème vient probablement de l'adaptateur secteur, de son câble ou de la prise de courant de l'ordinateur portable. (Attention, il est probable que votre batterie soit déjà complètement déchargée. Dans ce cas, vous devrez demander autour afin de trouver quelqu'un avec un ordinateur portable utilisant le même adaptateur ou un adaptateur similaire que vous pourriez essayer).

Some laptop power adapters have a power light. If this remains extinguished, the adapter is almost certainly dead. But before discarding it, check the fuse in the mains lead, and check that the mains lead itself is serviceable.

There are many different types of laptop mains adapter, but manufacturers tend to use one type for a range of similar models. If you need to try one which isn't identical to the original, firstly, make sure the plug is the same size. (A slightly oversized plug might damage the socket on the laptop.) Next, examine the label on the adapter and make sure its output voltage is the same, or at least within 1V. Lastly, make sure it's output current (in Amps) or power (in Watts) is the same as yours or greater.

Problems can be caused by a fault in the lead from the power adapter to the laptop plug, especially if this lead has been habitually twisted or wound around the adapter body. Try bending it at various points, particularly in the region of any kinks, and close the the adapter itself and the plug at the other end.

The power socket in the laptop can also get damaged. Try wiggling the plug in the socket to see whether that has any effect.

If you are unsure of the state of the battery, a small utility BatteryInfoView will display the status information held in the chip included in all laptop batteries.

If you still haven't located the problem, then it may be a fault on the motherboard. By all means disassemble the laptop to see whether there is anything obvious, such as failing electrolytic capacitors (see the capacitors page for details), or any components which have clearly overheated, or physical damage. If the laptop powers on but powers off again within a few seconds, it could be that the heatsink is no longer making efficient thermal contact with the processor, allowing it to overheat and automatically shutdown.

Repair

Replacement laptop batteries are available from a variety of sources, but the quality may be variable. In the worst case, a knock-off battery from an unscrupulous dealer and using a slightly different chemistry to the branded one could be a highly dangerous fire risk. Lithium batteries have a limited shelf life, so even a genuine branded battery might give poor performance if it's been in storage for a number of years. Wherever possible, always buy from a reputable seller, and make sure you can return it if it turns out to be faulty.

Replacement mains adapters, too, are readily available, but the same warnings about quality and safety apply. The best option might be to try and obtain an original adapter from another laptop of the same model that has died.

Laptop mains adapters are not designed to be repairable. Their cases are generally glued together very firmly as they would be highly dangerous if they came apart through an accident or incompetent tampering. For the same reason, whilst repair may not be totally out of the question, it must not be attempted unless you are completely competent in the repair and in securing the case again afterwards.

If the cable on the laptop side of the adapter is damaged it may be possible to cut out the damaged section, but you will need to take care to ensure that a replacement plug has the same internal and external dimensions.

If the power socket on the laptop is damaged, it may be possible to bend the springy metal leaves inside the connector in order to make better contact using a pin or similar tool.

In some laptops the power socket is connected to the motherboard via a flying lead, and the socket and flying lead may be available as a spare part. In others, it's soldered directly to the motherboard, in which case obtaining and fitting a replacement may be harder.

If you think the heatsink bonding to the processor may have failed, there are YouTube videos and other online resources showing how to clean off the old heatsink compound and how to apply the new. If you don't do it properly you could easily make matters worse.

Spare Parts

An eBay search will will throw up various sources of laptop batteries and mains adapters, but pay careful attention to the seller's reputation. If you purchase a replacement battery, make sure the vendor will accept returns in the case of poor quality parts.

If you search for a common replacement part such as a screen or keyboard, you will generally find several vendors who refurbish cast-off company laptops, and who may well be able to help with other parts such as a power socket.