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DMM stuck on .844 ohms
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Stu jaxon
Apr 29, 2021, 3:41:07 PM4/29/21
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Hi Group, can someone help please.? my craftsman digital multimeter 82344 not reading correctly, when i select the ohms or diode position to test components the display reads .844 on the ohms position and .556 on the diode position, it is stuck on those values, does not change. i did change the fuse, still the same.. it does read voltage and continuity.
Peter W.
Apr 30, 2021, 7:41:45 AM4/30/21
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Can you get to the switch? Something may have fouled the Ohms Setting.
Peter Wieck
Melrose Park, PA
Peter Wieck
Melrose Park, PA
Stu jaxon
May 1, 2021, 9:51:03 AM5/1/21
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Paul Hovnanian P.E.
May 1, 2021, 9:41:58 PM5/1/21
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Stu jaxon wrote:
>
> yes, the switch/selector isn't stuck. the ohms display is , i might have
> accidently tested a high voltage in the ohms setting, i don't remember.
> just wanted to know if it's fixable. i google it, and found zilch...
How is it reading in the Volts ranges? These things have only one A/D
>
> yes, the switch/selector isn't stuck. the ohms display is , i might have
> accidently tested a high voltage in the ohms setting, i don't remember.
> just wanted to know if it's fixable. i google it, and found zilch...
converter and display. Everything else is input conditioning, range
selection and (for ohms) a current source.
--
Paul Hovnanian mailto:Pa...@Hovnanian.com
------------------------------------------------------------------
I live the way I type; fast, with a lot of mistakes.
Phil Allison
May 1, 2021, 11:54:36 PM5/1/21
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Paul Hovnanian P.E. wrote:
====================
Rather, they read the *ratio* of two voltages, one across the unknown part and the other across an accurate reference resistor.
This is both simpler & far more accurate.
Also, they do not use normal A-D converters.
An analogue technique called " dual slope integration" converts the DC input voltage to a precise time interval.
This interval is used to pass clock cycles from a time base which counted and displayed in decimal form.
The "digital " bit is only the display.
..... Phil
====================
>
> How is it reading in the Volts ranges? These things have only one A/D
> converter and display. Everything else is input conditioning, range
> selection and (for ohms) a current source.
>
** Hand held DMMs do not use current sources for resistance measurement.
> How is it reading in the Volts ranges? These things have only one A/D
> converter and display. Everything else is input conditioning, range
> selection and (for ohms) a current source.
>
Rather, they read the *ratio* of two voltages, one across the unknown part and the other across an accurate reference resistor.
This is both simpler & far more accurate.
Also, they do not use normal A-D converters.
An analogue technique called " dual slope integration" converts the DC input voltage to a precise time interval.
This interval is used to pass clock cycles from a time base which counted and displayed in decimal form.
The "digital " bit is only the display.
..... Phil
Stu jaxon
May 2, 2021, 9:24:44 AM5/2/21
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