Identifying PCB components?

[Tom]

The 2 black square boxes in the centre of the picture. What are they? I think the top one is broke but without knowing what they are or do im just basing that on the difference between readings compared to the other. Cheers

[darrenjlobb]

Its a fet (mosfet)

Did you de solder it to read over it? else your just reading whatever else is connected in circuit...

[Tom]

Nope just probing in situ (giggidy)

Hmmm, Something in this power circuit is shot to shit, I'll have to remove the motherboard to de solder it wont i?

We're both talking about the 2 black boxes FDD6685 yeh?

[Jonny b]

No you won't have to remove the mother board! Get a heat gun on it, try to insulate parts that look like they will melt, how old is the the board? if its fairly newish get some leaded solder on the fet your taking off

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I'll have a look in stock in the morning see if I have any on the shelf

[Tom]

Heatgun? Whatever for haha? I feel i'm missing something. Not my lappy just a friend asked if i could take a look and i want to try and help him out :p

[Jonny b]

To take it off

[Tom]

Wouldnt i just use the soldering iron?

[Jonny b]

The 2 front legs yes, but depending on the iron you have and the solder that's on the board! If its a relatively new board it will be unleaded solder that has a much higher melting point you may struggle to get enough heat in the main pad to get it off without pulling pads up and damaging the board

[Tom]

Ahh alright buddy i get you now! What do they do first? lol

[cully]

http://www.fairchildsemi.com/ds/FD/FDD6685.pdf

[vincent1]

this is a very good site to use i use it mainly for lcd/plasma repairs its free to join the forum some great guides on testing and removing the fets on you tube best bet hot air gun imo can be done with a good soldering iron but post your problem up on the forum maybe a common problem there is already a answer to.

http://www.badcaps.net/forum/forumdisplay.php?f=23

[Jonny b]

It basically changes the signal that goes In we could be here all night as there are so many variations

[Ruan]

They're essentially an electrical switch that's controlled by electricity, it's a Power FET so it's probably using a low level computer voltage to switch something that consumes quite a lot of power...

Looks like that IC below the two fets is a Charge control IC, so they probably have something to do with the switching of the battery charge circuit...

[cully]

guide to testing the fet with a multimeter

http://www.4qdtec.com/mostest.html

[Jonny b]

Actually looking at it again that qfn looks to have a dry joint top right hand pin!! Can still see the gold finish on the pad. Not been dropped this lapto has it

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Also I can see 1206 components on 1210 package size pads tut tut

[Tom]

Its been dropped plenty.. and thrown i would of thought lol

[Ruan]

Lol glad someone else noticed the 1206 on 1210 pads....

[Tom]

Lol glad someone else noticed the 1206 on 1210 pads....

Explain? Does that mean someones been in side this one before? Or cos its ace and shit? haha

[Ruan]

Basically someone's put down pads that are sized for 1210 components, and put 1206 components on the board... 1210 and 1206 are basically standardized copper pad sizes for surface mount components.

[Tom]

Does my very shit multimeter have a "Diode Test Range"??

[Jonny b]

Lol glad someone else noticed the 1206 on 1210 pads....

Ha ha I build all sorts mostly prototypes


That was one I done last week all hand built!! 0402's and 0201's pain in the arse

[mcdub]

The red one mate

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Lol glad someone else noticed the 1206 on 1210 pads....

Ha ha I build all sorts mostly prototypes



That was one I done last week all hand built!! 0402's and 0201's pain in the arse

That cannot be easy. I'm an electrical design engineer and we do HV stuff, I wouldn't know where to start with surface mount components

[Tom]

Why cant the guide just say its the continuity thing -.-

[Jonny b]

Ha ha

[Niall]

Lol glad someone else noticed the 1206 on 1210 pads....

Ha ha I build all sorts mostly prototypes



That was one I done last week all hand built!! 0402's and 0201's pain in the arse

Jonny what is that for? Looks like its from a Apollo ISB

[Jonny b]

It was for targeting is all I can say bud

[Niall]

It was for targeting is all I can say bud

Ah not what i thought then. Was gunna say ive got one of them thats been smashed to f*ck in the back of my car lol

[Jonny b]

Ha ha yeh probably not something you would have in your boot

[cully]

looks like 4 gps receivers

[Jonny b]

looks like 4 gps receivers

Nope nothing like it now go away cully haha