Identifying an smd part

[simon.jowett]

Hi I'm hoping someone can help me with identifying an SMD part.  (see attached image)

The part is SOT89 sized and has the markings WH on one line then DKL on the 2nd line.

I've searched and the only similar parts I can assign a reasonable level of confidence is a DK part which is a NPN transistor.  I can see that this transistor sometimes has a sub code to denote the Hfe characteristics.  However I can't seem to find any with DKL or "L" characteristics.  The closest part was a 2SC4672-P - am I nearly correct ?!!!

Any advice would be much appreciated!

[denimdragon]

Can you take a pic with the surrounding circuitry? Maybe 1"x1"?

Also check this link out if you aren't already familiar with it...

http://www.s-manuals.com/smd

[simon.jowett]

The circuit is in a grid inverter.  The areas is right at the input and it's proabably taken a surge on the mains connection (complete guess).

The inverter is completely dead so I'm thinking this part of the circuit is the mains sensing and/or the control enabling function.

[digsys]

That's a tough one. Not on of my SMD books comes close enough. Your best bet is to remove it and trace the pinouts CBE. Verify that they could be an NPN, then try a best guess. Check the pinout against his mate next door as well, or even swap it to the dead location. Hopefully, someone may recognize it, otherwise it'll need a circuit trace.

[simon.jowett]

Thanks for looking - i'm drawing a blank too.  I think I'll remove the good one and see if I can get some info by testing it.

[fzabkar]

Those two parts (WH/DKL and the blown part) are directly driven from the same output of the TL074I quad op-amp. ICBW, but the only time I recall seeing an op-amp driving a transistor directly is when it is configured as the pass transistor in a feedback loop. Otherwise there is usually a series resistor in the base or gate. Even more unusual is that the op-amp is driving both "transistors", which rules out the idea of a pass transistor.

[denimdragon]

Those two parts (WH/DKL and the blown part) are directly driven from the same output of the TL074I quad op-amp. ICBW, but the only time I recall seeing an op-amp driving a transistor directly is when it is configured as the pass transistor in a feedback loop. Otherwise there is usually a series resistor in the base or gate. Even more unusual is that the op-amp is driving both "transistors", which rules out the idea of a pass transistor.

I was thinking PT as well but the jfet op-amp killed that...

[digsys]

Those two parts (WH/DKL and the blown part) are directly driven from the same output of the TL074I quad op-amp. ICBW, but the only time I recall seeing an op-amp driving a transistor directly is when it is configured as the pass transistor in a feedback loop. Otherwise there is usually a series resistor in the base or gate. Even more unusual is that the op-amp is driving both "transistors", which rules out the idea of a pass transistor.

Yep, same conclusions.
Option2: Remove the TL074 and the transistors? , take a photo, trace the tracks and work out how the heck it is wired. Then we may get a better picture.

[simon.jowett]

I'm away for a few days - will remove parts and try figure out a small schematic next week.