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Confirmation of transistor ID

D

dave

Jan 1, 1970
0
I've got a mitsubishi cctv time and date generator that has a duff
transistor but I can't for the life in me find out what it definately
is. Using a component analyser it says it's a NPN bipolar with the
following parameters: hFE=100, Ic=2.5mA, Vbe=0.79V & Ib=4.5mA (The
board has lots of these transistors on so these are the results from a
good one). It has the markings 724 with 76C below on the case, and
with the writing towards you its pin out is ECB. My best guess is that
its a MPS6724, can anybody confirm or say otherwise.
 
dave said:
I've got a mitsubishi cctv time and date generator that has a duff
transistor but I can't for the life in me find out what it definately
is. Using a component analyser it says it's a NPN bipolar with the
following parameters: hFE=100, Ic=2.5mA, Vbe=0.79V & Ib=4.5mA (The
board has lots of these transistors on so these are the results from a
good one). It has the markings 724 with 76C below on the case, and
with the writing towards you its pin out is ECB. My best guess is that
its a MPS6724, can anybody confirm or say otherwise.
Something's wrong with those numbers.
 
S

Sam Goldwasser

Jan 1, 1970
0
The fact that the same part number is used all over the board suggests
that it's just a general purpose transistor. Figure out which flavor
(NPN or PNP) and try a common transistor like a 2N390X as a replacement.

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dave said:
Sorry, I now realise you might mean the analysers numbers so here's a
copy of the realevent section of the users guide:

http://www.web-a-photo.com/showpic.exe?ID=295827&invite=c5d03e714ce5eab71f3dc3699d8eea52
Yup, that makes sense. What you posted does not:
"hFE=100, Ic=2.5mA, Vbe=0.79V & Ib=4.5mA"

The above line says you had a gain of 100 with a collector
current of 2.5 mA and a base current of 4.5 mA.
Impossible.

As far as replacing the transistor, my guess is that the circuit
is non-critical and you can probably use most any general purpose
NPN silicon that fits. Try a 2N2222 or something you have in
the junk box. Just measure the voltage that the transistor will
"see" first to make sure it's within whatever your replacement
can handle, and figure out where C,B,&E are on the PC board.
 
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