"legg" wrote in message
...
On Mon, 13 Aug 2012 16:03:50 +0100, "Gareth Magennis"
wrote:

Hi,

trying to ID a 3 terminal SOT 23 device on a PCB. It is marked 2.T I ,
except the I is not actually an I but an H on its side, so possibly marked
2.T H, dunno.

(I think its SOT23 cos it is just under 3mm wide)

There is one other of these on the PCB, and it measures in circuit like a
PNP transistor, i.e. 2 PN junctions at 671mV and 675mV on my Fluke.

There are other similar devices on the PCB marked "JG", "8.S 7(on its
side
again) and "2.X I".

2T on SOT23/TO236 is most commonly a surface mount version of 2N4403 -
MMBT4403, PMBT4403,SO4403.

Similarly 2X is it's compliment, MMBT4401.

SMD ident lists can be found fairly easily on-line, though none claim
to be comprehensive.

http://info.electronicwerkstatt.de/b...md/smd_aktiv/1
http://www.angelfire.com/electronic2/rch/smt.html
http://matthieu.benoit.free.fr/cms.htm

These links will come and go, as they are typically privately
maintained by amateurs.

Sometimes these markings are treated just like part numbers on some
websites, allowing for simpler searching.

http://english.electronica-pt.com/db...nce.php?ref=2x

RL



Fitted a new MMBT4403, and guessed the missing inline diode would be a
Schottky - there was a MBRS140 nearby, so fitted one of those.

And it is all now working, so thanks very much again for those links.



Cheers,


Gareth.