8 Krypton

Concern over possible safety issue with laptop charger/PSU

I have a Vostro 3750 laptop which is now well out of warranty, however yesterday evening I experienced a problem that has left me concerned over the safety of the original AC adapter.

As I went to connect AC power and the connection made, I experienced a moderate popping sound but also a fairly large flash from the connector as contact was made. I am an electronics engineer and well used to expected behaviour as power is applied in this manner, and this behaviour was enough to startle me. This incident also immediately tripped the household ELCB (earth leakage breaker) on the incoming mains supply suggesting that a fault current had passed down the protective earth lead in the 3 core lead.

I tested the charger in a safe environment fully expecting it to be dead, but it is not. Functionally it is fully operational. Odd, and I was surprised.

Returning the charger back to service however revealed that the 3 amp plug top fuse had also blown during this incident.

Piecing together the 'evidence' of what happened I suspect that one of the incoming mains filter components within the charger has failed, probably one of the filter capacitors typically connected between each line (both neutral and live) and ground.

This would account for the noise, the ELCB tripping and most conclusively of all, the 3 amp fuse rupturing. I also have a suspicion of a faint odour from around the inlet socket on the charger something again that would be consistent with a failure along the lines suggested.

My concern is safety related, despite the charger appearing fully functional some 'event' occurred internally to cause the mains to trip and the plug top fuse to blow. Given that the unit is fully sealed, it is impossible to confirm exactly what happened without partially destroying the unit in an attempt to open it. Of real concern is that there could be a component (filter cap for example) in a dangerous condition, possibly having partially burnt and carbonising the surrounding area. Although still working I feel the unit may not be safe.

Had the unit just failed, for example blowing an internal fuse and becoming non functional then that would be an end of the matter and just one of those things. The fact it did not do this, and is now outwardly fully operational but in a possible dangerous or compromised state (with regard to both safety and EMC interference) is the concern.

Your thoughts on the matter would be appreciated. 

 

 

 

 

 

 

  

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8 Krypton

Re: Concern over possible safety issue with laptop charger/PSU

If it helps identify or confirm the problem I noticed another thread that sounds remarkably similar:

Smoke and Sparks from Adapter

Below is a picture of my adapter. It appears pretty much identical.

Edit... can't find a way to get the forum image attachment to work. Lets try this, a OneDrive link:

https://va8nza.by3302.livefilestore.com/y4mtZBB4kh6PoNzhHfZHX_ibiUUd5WHl6nR82Hh6wfrleumO08TrQusj0uJy... 

 

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8 Krypton

Re: Concern over possible safety issue with laptop charger/PSU

If its fake thats a problem.

YD9W8 is a standard 90W adapter.

Get a 130W if you think its getting too hot.

http://www.dell.com/en-us/shop/accessories/apd/331-5817

 

YD9W8 AC Adapter


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8 Krypton

Re: Concern over possible safety issue with laptop charger/PSU

Definitely not fake. I bought the Vostro brand new and direct from Dell. This is the original charger we are talking about.  

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8 Krypton

Re: Concern over possible safety issue with laptop charger/PSU

A bit more on all this to hopefully bring this to some kind of conclusion.

As my main concern was over safety I opened and examined the charger in detail. It couldn't be left without knowing one way or the other.

I have to say that nothing untoward was found, either visually or under live testing and leakage testing.

So that leaves the very curious issue of what really happened and all I can do here is try and piece the sequence of events together.

1/ The connection was made and a spark (which is normal) was created. I am assuming the neutral pin connected first, making contact before the live (also a perfectly normal scenario). 

2/ My 'best guess' is that this spark somehow tracked across to the adjacent earth pin and in a manner somewhat like a lightning 'feeder' that precedes a strike, this relatively small spark was sufficient to allow and to carry a larger current into the earth lead thus both tripping the ELCB and blowing the plug top fuse.

The conditions must have been exactly right (or wrong whichever way you look at it) for the charger to draw a high inrush current at that moment, possibly being connected on the point of the mains cycle that would allow the highest inrush current and generate the highest spark. There is also the variability of manually plugging in a live connector. Was it a clean connect or was there a moments hesitation increasing the likelihood of 'drawing an arc' that allowed this to happen.

So something along those lines is my best explanation of this event. If others should come across anything similar then hopefully this will go some way to reassuring them.

 

 

 

 

  

 

 

 

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