Need Help to identify the device

Hi Renan, 

I too, have come up empty on identifying this device.  I've got some queries out to others who may have some info, and I'll let you know what I find.  

I did find a reference on DigiKey, but it's not quite the same device: 

https://www.littelfuse.com/~/media/electronics/datasheets/discrete_igbts/littelfuse_discrete_igbts_pt_ixg_40n120b2d1_datasheet.pdf.pdf 

I'll let you know what else I find.

~Leonard  

Hello Leonard,

Thank you for the help.

Hope you can find other information to help our customer. 

Regards,

Renan

Renan,

I don't believe TI ever sold NPN transistors. I suspect it is a voltage regulator based on sight and initiation (and a lack of any "how it is used" information)

Tell us more about what was connected and we may be able to help more.

It is bad or good, and how do you know that?

Hello Ron,

Please see the reply from the customer:

This mystery device comes out of a rheostat from the gauge cluster of my 1989 Volvo 740. It is used to vary the brightness of the gauge cluster's backlight lightbulbs. As far as I've been able to tell so far, the rheostat as a whole has 3 pins, one being 12V, the other being the car's ground, and the third I believe is an adjustable ground derived from a 10KΩ pot. I've attached a few images of the rheostat board scan, component values and location, and a schematic derived from these images.

I believe the PT1200 to be functional, solely based on the fact that the rheostat worked as intended prior to my disassembly for reverse engineering purposes. The reason I assumed it could be an NPN power transistor was because I measured the voltage drop between pins using my multimeter in diode mode, and found a drop of 526mV between pins 1 and 2, and 531mV between pins 1 and 3.

Regards,

Renan

Renan,

Your attachment didn't show up. Please try again. 

The most simple implementation is like this.  

Your original image has a component on the right that might be there to sense the temperature of the NPN.