about hFE multimeter test...

[ArameFarpado]

Hi all...

a transistor "BD435" is giving me 440 in hFE test on the multimeter, when
the tecnical data i've found tell me min=40 max=475...

does this mean the transistor is really in good shape?
can it be busted and still give a good hFE test result on the multimeter?

thanks
ArameFarpado

 

[Baron]

ArameFarpado wrote:

Hi all...

a transistor "BD435" is giving me 440 in hFE test on the multimeter,
when the tecnical data i've found tell me min=40 max=475...

does this mean the transistor is really in good shape?
can it be busted and still give a good hFE test result on the
multimeter?

thanks
ArameFarpado

It means it is within spec !

--
Best Regards:
Baron.

 

[Brian Gregory [UK]]

"ArameFarpado" <a-farpado.spam@netcabo.pt> wrote in message
news:fubam8$caq$1@news.datemas.de...

Hi all...

a transistor "BD435" is giving me 440 in hFE test on the multimeter, when
the tecnical data i've found tell me min=40 max=475...

does this mean the transistor is really in good shape?

Probably.

can it be busted and still give a good hFE test result on the multimeter?

It depends how good the multimeter's Hfe function is.

Check that if you disconnect B and connect only C and E the meter shows
either a low number (ideally 0 or no more than 1 or 2) or an error of some
kind.

--

Brian Gregory. (In the UK)
ng@bgdsv.co.uk
To email me remove the letter vee.

 

[ArameFarpado]

Em SĂĄbado, 19 de Abril de 2008 20:18, Brian Gregory [UK] escreveu:

"ArameFarpado" <a-farpado.spam@netcabo.pt> wrote in message
news:fubam8$caq$1@news.datemas.de...
Hi all...

a transistor "BD435" is giving me 440 in hFE test on the multimeter, when
the tecnical data i've found tell me min=40 max=475...

does this mean the transistor is really in good shape?

Probably.

can it be busted and still give a good hFE test result on the multimeter?

It depends how good the multimeter's Hfe function is.
Agreed

Check that if you disconnect B and connect only C and E the meter shows
either a low number (ideally 0 or no more than 1 or 2) or an error of some
kind.

connecting just E and C in the socket, it reads the same value for hFE.

so, it got me thinking that hFE measure is not a transistor test for
working/burned transistor...

do you use hFE measure to see if a transistor is busted?

thanks
ArameFarpado

 

[Charles]

"ArameFarpado" <a-farpado.spam@netcabo.pt> wrote in message
news:fudhfc$u6r$1@news.datemas.de...

escreveu:

"ArameFarpado" <a-farpado.spam@netcabo.pt> wrote in message
news:fubam8$caq$1@news.datemas.de...
Hi all...

a transistor "BD435" is giving me 440 in hFE test on the multimeter,
when
the tecnical data i've found tell me min=40 max=475...

does this mean the transistor is really in good shape?

Probably.

can it be busted and still give a good hFE test result on the
multimeter?

It depends how good the multimeter's Hfe function is.
Agreed

Check that if you disconnect B and connect only C and E the meter shows
either a low number (ideally 0 or no more than 1 or 2) or an error of
some
kind.

connecting just E and C in the socket, it reads the same value for hFE.
so, it got me thinking that hFE measure is not a transistor test for
working/burned transistor...

Could be a leaky transistor. The test is crude. I would not put any faith
in it.

 

[Brian Gregory [UK]]

"ArameFarpado" <a-farpado.spam@netcabo.pt> wrote in message
news:fudhfc$u6r$1@news.datemas.de...

escreveu:

"ArameFarpado" <a-farpado.spam@netcabo.pt> wrote in message
news:fubam8$caq$1@news.datemas.de...
Hi all...

a transistor "BD435" is giving me 440 in hFE test on the multimeter,
when
the tecnical data i've found tell me min=40 max=475...

does this mean the transistor is really in good shape?

Probably.

can it be busted and still give a good hFE test result on the
multimeter?

It depends how good the multimeter's Hfe function is.
Agreed

Check that if you disconnect B and connect only C and E the meter shows
either a low number (ideally 0 or no more than 1 or 2) or an error of
some
kind.

connecting just E and C in the socket, it reads the same value for hFE.

The transistor's f***ed.

so, it got me thinking that hFE measure is not a transistor test for
working/burned transistor...

do you use hFE measure to see if a transistor is busted?

It's only quite recently that I've owned a meter with a transistor test
function on it. I normally do what I used to do and use a highish ohm range
and a wet finger to apply bias to the transistor. You check that the wet
finger produces much more deflection (lower reading on a DMM) when used to
apply bias than it does when applied directly across the probes. If you want
to be a bit more scientific you replace the wet finger with a resistor of
known value.

thanks
ArameFarpado

--

Brian Gregory. (In the UK)
ng@bgdsv.co.uk
To email me remove the letter vee.