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Testing a Multimeter

Hello all,

I am looking at buying a used Fluke multimeter (either an 8060A or a
77-III) from a local guy and I'm looking for simple tests I can do on
each meter. Neither meter has a current calibration so I certainly
don't expect the either to be perfect. I may send it off for a proper
calibration after buying it, but at this point I'd just like to test
that the meters are fully functional. I have a regulated dc supply, a
new carbon-zinc battery and some 0.02% resistors (1,100,10K) that I
could bring for basic circuit tests. If the dc voltage, dc current and
resistance all checkout ok, can I assume the AC functions are ok?
Beyond obvious signs of damage, Is there anything in particular I
should look out for?

Thanks,
Jamie
 
J

John Fields

Jan 1, 1970
0
Hello all,

I am looking at buying a used Fluke multimeter (either an 8060A or a
77-III) from a local guy and I'm looking for simple tests I can do on
each meter. Neither meter has a current calibration so I certainly
don't expect the either to be perfect. I may send it off for a proper
calibration after buying it, but at this point I'd just like to test
that the meters are fully functional. I have a regulated dc supply, a
new carbon-zinc battery and some 0.02% resistors (1,100,10K) that I
could bring for basic circuit tests. If the dc voltage, dc current and
resistance all checkout ok, can I assume the AC functions are ok?


---
Look for a transformer which you can use to check the AC voltage
ranges with, and then, knowing that voltage and the resistances of
your resistors, use:

E
I = ---
R

to calculate the current through the resistor(s) when they're in
series between the transformer's output and the meter's inputs.
 
H

Homer J Simpson

Jan 1, 1970
0
I am looking at buying a used Fluke multimeter (either an 8060A or a
77-III) from a local guy and I'm looking for simple tests I can do on
each meter. Neither meter has a current calibration so I certainly
don't expect the either to be perfect. I may send it off for a proper
calibration after buying it, but at this point I'd just like to test
that the meters are fully functional.

Just check that all ohms and volts ranges appear to work OK. That may be
more than enough.
 
C

Chris

Jan 1, 1970
0
Hello all,

I am looking at buying a used Fluke multimeter (either an 8060A or a
77-III) from a local guy and I'm looking for simple tests I can do on
each meter. Neither meter has a current calibration so I certainly
don't expect the either to be perfect. I may send it off for a proper
calibration after buying it, but at this point I'd just like to test
that the meters are fully functional. I have a regulated dc supply, a
new carbon-zinc battery and some 0.02% resistors (1,100,10K) that I
could bring for basic circuit tests. If the dc voltage, dc current and
resistance all checkout ok, can I assume the AC functions are ok?
Beyond obvious signs of damage, Is there anything in particular I
should look out for?

Thanks,
Jamie

In addition to the other advice (check AC, too -- use a transformer on
one of the lower ranges, and also test line voltage), have the seller
open the case (one screw on the 77-III, 4 on the 8060 AFAIR) and look
at the circuit board. See if there's any damage or blown traces(not a
killer in itself -- some of mine have been offered for Baptism of Fire
and been repaired by me without problem) and make sure it looks to have
been repaired competently. I believe there's a 1K fusible link on the
77-III (there is one on the 77 and 77-II). It blows when you try to
measure the resistance of the AC line. Make sure that hasn't been
replaced with a 1K 2 watt resistor. That's a nasty thing to do --
replace the safety component with a commonly available non-safety one,
then sell it before she blows), but it's been done. Without a fusible
resistor, the IC and your meter will be dead for sure on the next
fault.

If there is visual evidence of a repair, have the seller take out the
assembly and look on the underside of the circuit board -- check for
workmanship there, too. Caveat Emptor, and all that. Retest after
putting it back together.

If the seller won't cooperate, chances are there's something to hide.

Good luck
Chris
 
M

Mr. Wizard

Jan 1, 1970
0
If both meters are functional you can cross calibrate to see if one of
them is damaged. As long as the readings are withing the meter's
specification you should be o.k. You can use your power supply and
resistor assortment to check out the resistance, D.C. voltage and
current ranges.

You can do a crude check of the A.C. by checking the mains. If your
bold enough (balls enough) you can use your resistors to exercise the
A.C. ranges on the meter. CAUTION: IF YOU DON'T KNOW WHAT YOUR DOING,
I WOULD WARN AGAINST DOING THIS. IT COULD BE FATAL.
 
J

John Fields

Jan 1, 1970
0
If both meters are functional you can cross calibrate to see if one of
them is damaged. As long as the readings are withing the meter's
specification you should be o.k. You can use your power supply and
resistor assortment to check out the resistance, D.C. voltage and
current ranges.

You can do a crude check of the A.C. by checking the mains. If your
bold enough (balls enough) you can use your resistors to exercise the
A.C. ranges on the meter. CAUTION: IF YOU DON'T KNOW WHAT YOUR DOING,
I WOULD WARN AGAINST DOING THIS. IT COULD BE FATAL.
 
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