Please help identify a mosfet

Hi all,

Hope someone can help me identify this. This is a chip on a motherboard for HP MediaSmart Server. Several users (including me) have problems with front panel LEDs and have traced the problems to this. On my motherboard it has visibly burned out, on some others' it's not apparent. There seem to be at least 2 versions of the mosfet, so hopefully we can find a suitable replacement.

My burned out chip:


and from a different angle:


another user's 340 (looks like markings are different here):


different mosfet, should have same functionality:



Hope someone here can help!

And where are the pictures pls?

I think you should first of all find out what make the fet get burnt,b4 replacing another one, also you can find another fet in any scrab of mother board of computer,but you have to know the main function of the fet in the first place. is it used as a swich or amplifier and what is the max.Vgs,Vds,Ids.etc b4 fix in another one.

340 FDV340P Fch M SOT23 p-ch mosfet 20V 70 mA

HTH

karesz said:

And where are the pictures pls?

Click to expand...

They should be inline with the message... maybe you have tinypic.com blocked for some reason?

kabiru said:

I think you should first of all find out what make the fet get burnt,b4 replacing another one, also you can find another fet in any scrab of mother board of computer,but you have to know the main function of the fet in the first place. is it used as a swich or amplifier and what is the max.Vgs,Vds,Ids.etc b4 fix in another one.

Click to expand...

How do I go about that? Mine burned out twice - first time when I didn't notice it (that made it burn out internally only). Then, when I reconnected the board with LEDs several times while computer was powered, it burned out externally -- but the LEDs turned on. They went off when I desoldered the burned chip.

zasto said:

340 FDV340P Fch M SOT23 p-ch mosfet 20V 70 mA

Click to expand...

I saw this on http://www.marsport.org.uk/smd/smd3.htm a while ago.. problems with this:
a) I can't be sure it's that part
b) Can't find FDV340P on digikey and mouser.. I've found FDN340P on fairchildsemi and mouser and digikey.. and from the images/etc it looks like it might be that, but still can't be sure it's right.

I can't be sure it's that part

Click to expand...

There won't be much same package parts with identical marking. You may want to verify the principle device type (polarity, BJT/FET) as an additional check.

How do I check those?
I'm pretty much a beginner when it comes to these things. I more or less know how to check polarity and have rudimentary knowledge of how to use a scope.

Update: someone told me they know from a "reliable source" that this is a AO3409 P-Channel Enhancement Mode Field Effect Transistor.
Will try one of those

Fry-kun said:

Hi all,

Hope someone can help me identify this. This is a chip on a motherboard for HP MediaSmart Server. Several users (including me) have problems with front panel LEDs and have traced the problems to this. On my motherboard it has visibly burned out, on some others' it's not apparent. There seem to be at least 2 versions of the mosfet, so hopefully we can find a suitable replacement.

My burned out chip:

and from a different angle:

another user's 340 (looks like markings are different here):

different mosfet, should have same functionality:

Hope someone here can help!

Click to expand...

Hi,
Check markingcodes' original type no is our major job.Welcome to join our gold member.
The markingcode promblem you post, i checked them for you.see below:
-----------------------------------------------------------------------------------------
340 FDN340P SOT23/SuperSOT3 MOSFET--20V Single P-Channel 2 ... FAI
-----------------------------------------------------------------------------------------
A3xx AO3403 SOT23 Single - P ... AOS
-----------------------------------------------------------------------------------------


David
david@smdok.com
https://www.smdok.com
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Good luck!