What is the function of these things? Inside a Lenovo charger

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alberizo
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What is the function of these things? Inside a Lenovo charger

#1 Post by alberizo » Sat Nov 18, 2017 9:10 am

Hi. I opened a Lenovo 65W laptop charger and I'm curious about two things.

The metal shield is rounding all the charger. It's conected to earth, but has any more function? My guess it is a shield to avoid interferences. What do you think? I'm going to change a cable without earth, what about if I remove this shield? It does not have any heat dissipation function.
https://preview.ibb.co/mAY5Cm/0_IMG_20171117_205256.jpg

And what about the white adhesive that is everywhere? It's like sikaflex or another polymer adhesive, but is aplied with very little care. I don't think heat dissipation is happy with this.
https://preview.ibb.co/j9dGJR/0_IMG_20171118_144436.jpg

Googling I found a guy reparing a HP laptop charger and I was very impressed because it looks a clone of Lenovo or vice versa :eek:
https://www.youtube.com/watch?v=Hz5sL3fjT70

axur-delmeria
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Re: What is the function of these things? Inside a Lenovo charger

#2 Post by axur-delmeria » Sat Nov 18, 2017 12:55 pm

1. EMI shield.
2. If I'd have to guess, it's a damper for the inductors.
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Re: What is the function of these things? Inside a power brick.

#3 Post by automobus » Sat Nov 18, 2017 8:45 pm

That metal shield might contribute to heat distribution. Not necessarily so in your power brick. It is a common sight, in such compact regulated DC power supplies, to find that metal foil/sheet shield indirectly contacting hot parts (power MOSFET, voltage regulator) via thermal pad.

That white stuff (like caulk, and harder than silicone) might be placed to prevent a fault/leak/short across condensed moisture. Might, maybe; I am only guessing; I likely am wrong. I noticed it in several power supplies which include that encasing metal shield. I observe, it is usually applied onto circuit components which are tall or near to that metal case. I assume its purpose is electrical isolation/insulation, where air humidity condensate could form.

alberizo
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Re: What is the function of these things? Inside a Lenovo charger

#4 Post by alberizo » Fri Dec 01, 2017 11:33 am

Thanks for responses.

I opened a new subject talking about this
viewtopic.php?f=12&t=125131

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