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

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

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":

For other possibilities, check page 301 and onwards of this NEC selection guide:

- Franc Zabkar

application":

guide:

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.

On Mon, 18 May 2009 13:46:36 -0700 (PDT), lardconcepts put finger to keyboard and composed:

application":

guide:

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

Maplin, sadly, are pretty useless for components these days. Try RS, CPC, Farnell, Rapid etc. All sell retail by credit card.

application":

If you want to learn about electronics, don't ever go to Maplin. You will be told and sold a load of rubbish.

Here's somewhere else you can try if Farnell, RS, CPC etc are tricky with one off small quantities:

Gareth.

application":

guide:

How do you get on with Cricklewood these days, Gareth ? I used to use them a lot, but since they became part of that bigger group, I seem to have had endless problems with items not being in stock - although you don't get to know it until the delivery is missing that item - and then having to wait sometimes a couple of weeks or more, until they can get it. A couple of times, that caused me embarrassment with a customer, when I had told them when their repair would be ready, based on having ordered a part from them, only for it not to turn up, so recently, I have stopped ordering from them.

Arfa

application":

guide:

Well funny you should say that cos up til now they have been fine. Haven't used them for a couple of months or so now, but I Internetted an order yesterday for some Power transistors and a hard to find driver - this morning I received the power transistors but not the now even harder to find driver :( And no explanation either, just that missing line highlighted in luminous green.

I wasn't aware they had been taken over, perhaps this is the end of what was a very useful company to know (I could usually find all the odd transistors/old DRAMs etc I ever wanted)

Gareth.

To be honest, I am not absolutely certain that Cricklewood have been taken over. The work that I do mostly at the moment, calls for components from the likes of Farnell and RS. It was a colleague who told me that Cricklewood were no longer owned by the original people, when I mentioned the 'short' deliveries I had received a couple of times.

Another 'small' company that used to be very good, were Grandata, but they have definitely been taken over by some larger group, who seem to have rationalised the stock. I no longer use them, as it had reached the point that every time I rang them to check a stock position on an item, it came back as nil.

For 'oddball' chips, including some of the esoteric types used on SMPS, you might try Dalbani / Nikko

Again, their deliveries can be a bit variable, but they do carry a lot of less mainstream parts.

Arfa

Thanks for the suggestion - I sent them a close-up of the burnt controller and motor, and they suggested it might be a 2SK2134 @ =A31.50

Was slightly disappointed to find that 67p of stamp and envelope is charged at =A33 making a total of =A35.18 inc, and normally I'd have shopped around (ie: vintage-parts.com would have been =A33.15 total) BUT I was happy to pay the extra =A32 as a service for the help.

Unfortunately, I guess it wasn't the right part, as I DO have a working drill again, but it's got two speeds now - stop and go!

So, semi-result, and I've learnt a bit along the way, so thanks for everyone's help!