how can I desolder dpak(t0252) mosfet from mainboard?

[bshi02]

I located mosfet on mainboard which was getting very hot whenever I turn on my comp.(and It won't boot up a post screen)
its 3 pin soldered to 3 solderring pad(especially one pin seem to soldered at the bottom) and it seems to demount it with normal solder iron is nearly impossible.
Is there any simple way to desolder dpak mosfet from mainboard?
and How can I test dpak mosfet for abnormality?

[shorteddiode]

Re: how can I desolder dpak(t0252) mosfet from mainboard?

Some times you have to add solder to desolder.

[bshi02]

Re: how can I desolder dpak(t0252) mosfet from mainboard?

I have known very well that to add lead usually ease desoldering task.
But It would not do any good at all for desoldering smd mosfet(D-pak)

I heard today that in order to detach to252 type of mosfet from mainboard, Computer repairer usually use hot air gun.but I want to make it this task with common solder iron not with hot air gun.
Is there any ways to desolder dpak mosfet with solder iron?

[budm]

Re: how can I desolder dpak(t0252) mosfet from mainboard?

I 2nd that shorteddiode.That is the trick I always use when I am trying to remove component off the board.
I use Weller 60watt with wide tip. Wattage of the soldering is important, the added solder will keep the part hot.
How to solder was the first thing I was taught in the first day of the electronics class.

[mattpd]

Re: how can I desolder dpak(t0252) mosfet from mainboard?

I get them off by heating the legs and lifting (bending) them slightly up until they are free of the pad. Now just the big base is left. Use a blade tip and max heat. Hopefully they left you a little piece of solder pad sticking out of the back, under the wide metal back pin. This will make transferring heat under the chip more efficient. Pile on solder in this area and onto the big metal pin and keep it molten by holding the tip there. It will eventually break loose. It may take a minute. I have hot air but I would rather use this method.

If you don't have a 60w iron it will be hard. If you don't have a blade tip it will be even harder. Use your widest tip and keep moving it back and forward on the metal. If you have a bottom heater it will no problem. A $25 pancake griddle will suffice for this job.

[severach]

Re: how can I desolder dpak(t0252) mosfet from mainboard?

It's much more likely that a power supply transistor is getting hot because it is working at max power to supply a shorted chip rather than the transistor itself is shorted. Even worse, if the transistor is shorted and the driver IC and circuitry is too simple to detect and force shut down then any chips supplied may already be destroyed. You'll need to remove the transistor without destroying it to be sure. If you don't have a SMD hot air gun DPAK and D2PAK can be removed with 3 solder skilled hands and 3 irons. Finding a 3rd hand that knows how to solder SMD is usually an insurmountable problem so put them on tab duty.

Sorry to take the wind out of your sails but that's how the cards usually fall. Feel the chips to see if they get hot. Pull heat sinks if necessary.