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Unknown component, SOT-23 package?

TBennettcc

Dec 4, 2010
292
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Dec 4, 2010
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Good afternoon, everybody. Hope everybody is set to have an enjoyable weekend.

I'm working on a two-wire intercom system outdoor unit (first one I've ever worked on.) I'm trying to troubleshoot a problem, and even though this question is further in the circuit than my problem should be, I'm trying to make a schematic anyways.

I have what appears to be an SOT-23 package, with a triangle with a "T" in the middle of it, followed by " : 8 Y ". Not at all familiar with SOT-23's, but the little bit of research I was able to find suggested that not all SOT-23's have the same pinout, so I'm at a loss here. It's possible it's not even a transistor (I found some zener diodes in an SOT-23 package), although I'm not sure that would make sense, as all three pads appear to be landed, and I would assume it's some kind of amplifier circuit (it's going to a speaker)

Pictures: http://s994.photobucket.com/user/TBennettcc/library/Unknown SOT-23 component

I've Googled and found some articles that show you how to determine E,B,C of a transistor, but I'm getting readings in both directions with my DMM in diode mode.

I can also post what I have of the schematic so far (EAGLE CAD files, or maybe a PDF of the schematic), if anybody thinks that would be helpful. There are a few components I'm not sure about their ID, so I've made some best guesses.

Thank you so much for your help.
 

Surf Rider

Sep 16, 2013
5
Joined
Sep 16, 2013
Messages
5
Hey Tim,

I've been using a site to figure out smd components recently which has proved quite useful.

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

I've got some SOT-23 zener diode in my circuit where all 3 terminals are landed but only pin 1 and 3 actually connected in the package.

Hope this helps, if you think its a diode you can always check this out with a diode enabled meter.

:)
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
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That reference (useful BTW) suggests it is an 18V zener.

My reference lists about 8 options. All are roughly comparable 18V zeners. They range from 225mW to 500mW.

Almost all have the same pinout. The exception are the parts TMPZ5248 and TMPZ5248R. The latter is listed as "reversed". This is especially relevant because the part has a T designator and mat be one of these (I don't know). I would look at the datasheet for the parts listed above and see if they describe the T in a triangle, and if so, do they indicate how to differentiate between the normal and the reversed part?
 
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