Cordless drill speed control chip burnt out. Can anyone identify itfrom this?

[lardconcepts]

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 here http://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!

Unfortunately, I don't live somewhere I can just wander into a Maplin,
and Googling doesn't help, so any help appreciated. Thanks



The motor is a HongYang HRS-550S-18V

 

[Franc Zabkar]

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 here http://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-datasheets/Datasheets-22/DSA-432531.pdf

For other possibilities, check page 301 and onwards of this NEC
selection guide:
http://www.datasheetarchive.com/pdf-datasheets/Datasheets-16/DSA-317291.pdf

- Franc Zabkar

 

[lardconcepts]

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-datasheets/Datasheets-22/DSA-4325...

For other possibilities, check page 301 and onwards of this NEC
selection guide:http://www.datasheetarchive.com/pdf-datasheets/Datasheets-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.

 

[Franc Zabkar]

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.

In your part of the world you should have a huge choice of equivalent
MOSFETs by ST Microelectronics, for example. Have a look at Farnell's
range, or RS Components.

BTW, you should check your motor before proceeding. It could be that
the brushes have worn down, or that carbon dust has shorted the
commutator segments, or that the motor windings have shorted.

I would remove the MOSFET and link its drain and source pins with a
piece of wire. This should get the drill operating at full speed. If
all is not OK, then it probably won't be worth repairing.

- Franc Zabkar