On 18 May, 21:28, Franc Zabkar wrote:
On Mon, 18 May 2009 13:01:26 -0700 (PDT), lardconcepts
put finger to keyboard and composed:

Spear and Jackson Cordless Drill model SJ-CD18KUK

Worked fine for years, mechanically sound. Now after a short time of
use, there's a puff of smoke and it slows right down. Upon opening up,
I see this smoke is pouring from the centre of a 3-legged regulator
device on a heatsink.

I have looked herehttp://www.maplin.co.uk/Search.aspx?menuno=12489
but can't find anything with similar numbers. The markings are
NEC
K2 ??4
82M

The ?? are two numbers I can't see, as that's where the burnt hole is!

I suspect it is a 2SK2??4 MOSFET which is being switched in PWM mode
to control the speed of the motor.

One possible suspect is a 2SK2984 20A 30V "SWITCHING N-CHANNEL POWER
MOS FET INDUSTRIAL USE ... designed for high current switching
application":http://www.datasheetarchive.com/pdf-...ts-22/DSA-4325...

For other possibilities, check page 301 and onwards of this NEC
selection guide:http://www.datasheetarchive.com/pdf-...ts-16/DSA-3172...

Wow, Franc, I am very impressed! OK, sadly it seems that I might have
my work cut out finding this chip. Certainly not Maplin that sells it,
or in fact any of those chips.

But you have given me a very good start. I wish I knew as much about
electronics.