Fiery Mosfet on Imac LB!.

[deckart]

It's time to call in the experts again!.
Background:Imac G5 2.1 Isight.
Switch on nothing.No chime.I replace with good known,power inlet,DC to DC board,AC to DC board,connect mains lead,LED 1 on,yippee,switch on,LED 2,more yippee,oh no!,MOSFET commits hari kari by impersonating a volcano,1" flamer!.Power down.
It's this:30V Single N-Channel HEXFET Power MOSFET in a SO-8 package.I can get a replacement but before would love to hear your opinions as to why this would happen.All the replaced parts were from an exact model,all parts cross referenced.
Cheers!.

[Toasty]

Re: Fiery Mosfet on Imac LB!.

Pinched wire causing a short?

>> power inlet, DC to DC board, AC to DC board<<
What/where are these parts?

>>MOSFET commits hari kari<<
Which MOSFET? Where?



Toast

[deckart]

Re: Fiery Mosfet on Imac LB!.

OK,hope you make head or tails out of these pics!./Users/jpbarford/Desktop/Photo0150.jpg/Users/jpbarford/Desktop/Photo0151.jpg/Users/jpbarford/Desktop/Photo0155.jpg

[deckart]

Re: Fiery Mosfet on Imac LB!.

Woops you have a time out facility!,I was just modifying the pics.
Inlet is the pic of back of Imac,kettle lead in the hole!.
Pic of insides.Top left is ACto DC,to the left is DC to DC/invertor.
Other blurry pic is MOSFET of another board with broken leg.
Hope this leads to something!.

[Toasty]

Re: Fiery Mosfet on Imac LB!.

Where is the blown MOSFET?

Why do you say the MOSFET you pictured has a broken leg? Did you break it?

[deckart]

Re: Fiery Mosfet on Imac LB!.

Hi Toasty,blown MOSFET has been removed/fell off on its own accord.Pic is of another LB I have of exact same LB.Leg fell off whilst desoldering,so that was pretty ropey as well.I'm getting confused!.I'm going to do another pic of LB with silkscreen position of MOSFET.
I'm pretty crap at editing pics so bear with me.

[Toasty]

Re: Fiery Mosfet on Imac LB!.

Numbers/letters from the chip please. Line-by-line

Also, an overall shot of the board. Turn off the flash, turn up the room lights, or at least take the shot with no flash reflection. The glare is a bit much .

The MOSFET probably went *poof* because of a catastrophic failure elsewhere on the motherboard or a shorted component that it powers. You have to determine what is fed from that chip.

[deckart]

Re: Fiery Mosfet on Imac LB!.

Right,sorry Toasty,I'm better frying an egg than taking pics,especially if it's a camera phone.I'm going to borrow a friends real camera and post the pics,is it ok to PM you when I've done this?,I would really like to gain some of your knowledge on this as I have 2 Isight G5 boards which display exact same faults.I have checked over the blown MOSFET board but can't see a nything which would cause a short.
All the best.

[Toasty]

Re: Fiery Mosfet on Imac LB!.

Please post any questions, comments, or information in the forum. PM'ing doesn't benefit the members or any who come looking for info later on...

That being said, I'm learning too with the info you provide and the pics will help me to see what you see. I've not been intimate with the iSight units, so the learning curve may be severe.

Hopefully, there are others here who have worked on them and will bring their insight to the thread.

Good to hear better pics are coming.

Toast

[deckart]

Re: Fiery Mosfet on Imac LB!.

Sorry about the delay life got in the way!.Been in conversation with the ebay seller,he forgot to inform me that he performed a HW test on this and omitted it came up with a nvram error before it died completly, basically it's FUBAR.
Off to Paypay resolution centre.
My fault in a way,now before I buy anything on Ebay I ask if it's been tampered with or the results of AHT.

[Toasty]

Re: Fiery Mosfet on Imac LB!.

That's a shame. Sorry you got burned. No pun intended...

Toast