Date: Thu Aug 7 11:45:58 2008

Author: Bill Norwood

Subject: Labor-Intensive Fuse Replacement in DMM's

Post:

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Hi Taplers,



For over 20 years it was necessary to disassemble our Keithley Model 168
digital multimeters

every time a fuse blew in the current-measuring circuit, and that was often.


Now it's 20 years later, and, guess what, the meter-makers

still haven't gotten the message that students blow a lot of fuses.

Yes, I know, students NEED to blow fuses

just to live out the foolish experience of improper circuit testing.

It's just that I do not need the experience of the consequences,

and we cannot trust the inexperienced students to take apart the meters for
fuse replacement.



So far I have not been able to identify a new meter model which has the fuse
externally replaceable.

For example, the following do not have this facility:



Keithley 168 (old)

BK Precision 2831D (~$300)

HP 34405A (recent $674 quote)

Instek GDM-8145 (recent $310 quote)



So, it will probably be a project of modifying each meter for external fuse
replacement,

as I did with one of the Keithley 168's.



Thanks for any remarks or other information.



Bill Norwood

U of MD at College Park




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Hi =
Taplers,

=


For over 20 years it was necessary =
to disassemble
our Keithley Model 168 digital multimeters

every time a fuse blew in the
current-measuring circuit, and that was often. =


Now itís 20 years later, =
and, guess
what, the meter-makers

still havenít gotten the =
message
that students blow a lot of fuses.

Yes, I know, students NEED to blow =
fuses

just to live out the foolish =
experience
of improper circuit testing.

Itís just that I do not need =
the
experience of the consequences,

and we cannot trust the =
inexperienced students
to take apart the meters for fuse =
replacement.

=


So far I have not been able to =
identify a
new meter model which has the fuse externally replaceable. =


For example, the following do not =
have
this facility:

=


Keithley 168 =
(old)

BK Precision 2831D =
(~$300)

HP 34405A (recent $674 =
quote)

Instek GDM-8145 (recent $310 =
quote)

=


So, it will probably be a project =
of
modifying each meter for external fuse replacement, =


as I did with one of the Keithley =
168ís.

=


Thanks for any remarks or other
information.

=


Bill =
Norwood

U of MD at College =
Park

=








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