The casing is a fairly standard design, so what's special about the transistor? What's its function in the circuit, what voltage / current / frequency? The part number appears to be incomplete - not unusual on a surface mount device - so there just isn't enough to work on at the moment.
  

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If we learn from our mistakes I'm getting a great education!
 

These parts are off a viewsonic VG150 inverter board.  I dont really know any more about the parts than this.

Hoping someone can help.

Correction......its a VG151 inverter board.

Why not ask Viewsonic?

TTFN

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I did contact Viewsonic.  They were not much help at all.  They wanted to sell me a "new inverter".....all i want to do is fix the one i have for a lot less money.  

I tried contacting the manufaturer in china but they have not responded to my 3 emails.

The package appears to be a SOT-89 or TO-283AA

Some suppliers have documents listing package markings. I suggest you do a search.

Thanks.  I have looked at the web sites which refer to surface mount device codes but i can not determine anything definative from them.  I guess the monitor is going in the trash unless i can figure it out.

How do you even know that's the bad part?

TTFN

FAQ731-376: Eng-Tips.com Forum Policies

Using a multimeter i ohmed out most of the inverter board.  I noticed one of the caps looked "different" so i started testing devices in that region.  A cap is bad (easy to replace) and the two devices i mentioned are bad and one of the transformers is bad.

I just looked at your pic... you do realize the tab and pin are supposed to be connected internally, right?

Dan - Owner
http://www.Hi-TecDesigns.com

yes.....the tab and pin 2 are connected/shorted.  

Basically since i dont know what the devices are I compared devices on one side of the board (that are exactly the same) to devices on the other side of the board.   In doing so i foudn a few devices that were essentially shorted.  These are the devices i am trying to replace.  

I just cant believe i cant find a replacement.  It really just frustrates me .

Thanks.

David

I don't think you understand... those pins are supposed to be shorted.  There's nothing wrong with them (at least due to the short you found).

Dan - Owner
http://www.Hi-TecDesigns.com

Yes, on the "YB" device they are shorted.  But these are not the shorted pins i am referring to.

But thanks for responding.

I had a similar issue trying to find a part, all I did was contact either 247Components.com or digi-key.com and ask for assistance from one of their engineers. They tend to be pretty resourceful when they think there's a chance of a sale in it for them. Good luck

Jay,

That would be true if this were more than a one-off replacement and something more costly than a $0.05/pc transistor.

Dan - Owner
http://www.Hi-TecDesigns.com

Just wanted to let you all know that i finally found the YB device.  It was from a company KEC in Korea.  I found the data sheet and then ordered a similar part from Digikey.

Put the part in and the LCD monitor worked!!!!!!!!!!

How did you find it?  Any tricks for the rest of us?  

Z
 

persistance.........i got lucky and found a link which referenced the company.  The part in the link was not the part i was looking for but i searched the company's site and there it was.  Trust me i tried just about everything:  Forums, calling major electronic distributors, everything........just by luck i found the link.  I had almost given up but had 5min one day and started looking again and thats when i found the link.  Guess its good to put it down for a while and come back to things.