Broken Multimeter?

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Old 11-03-20, 10:49 AM
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Broken Multimeter?

Hello,
I'm not really sure if this is the right forum for this, but I seem to be having issues with a digital multimeter. When I set it to AC and go to test an outlet it will generally flash between "----" and ".0F" or "0.F" (see pictures below). When I test the outlet with a different meter I get the normal 120v as expected. I got the second meter a few years ago when the first one was acting up but just got around to try and troubleshoot it some more.

When I try to test the continuity of a wire the older meter seems to work correctly when both ends are touching the wire, but will also flash with the 0F when there is no continuity. I tried replacing the battery already, but not really sure what to do otherwise.

I have tried leaving the tester on the 'auto' function and selecting the AC option.

I also realize it's a 15yo cheap meter, so that might be my answer...

As always, I appreciate any insight.




 

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11-03-20, 06:17 PM
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I'll bet the meter got put on the ma scale by accident and probably blew an internal fuse.
That would explain the F in the display.
See if there is a visible fuse in the battery holder area.

On further investigation.... there is a fuse but I can't find the size.
Radio Shack 22-820 meter.

R/S manual in pdf below.
 
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820m.pdf (264.6 KB, 13 views)

Last edited by PJmax; 11-03-20 at 06:32 PM.
  #2  
Old 11-03-20, 05:52 PM
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If continuity test works correctly, then your leads are good.
May be you have a bad contact under mode selector switch?

You will have to open it up to check if anything is wrong inside, but probably not worth repairing if it is more than cleaning contact or resoldering bad solder joints.
 
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Old 11-03-20, 06:17 PM
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I'll bet the meter got put on the ma scale by accident and probably blew an internal fuse.
That would explain the F in the display.
See if there is a visible fuse in the battery holder area.

On further investigation.... there is a fuse but I can't find the size.
Radio Shack 22-820 meter.

R/S manual in pdf below.
 
Attached Images
File Type: pdf
820m.pdf (264.6 KB, 13 views)
Adam L, beelzebob, CasualJoe voted this post useful.

Last edited by PJmax; 11-03-20 at 06:32 PM.
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Old 11-03-20, 10:31 PM
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Fresh Battery?
Digital meters will act funny when battery is low.

RR
 
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Old 11-04-20, 08:54 AM
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It appears the fuse is blown as tested by the other meter. I have some new ones on the way and will report back if that hasn't solved the issue.

On the off chance anyone needs the size in the future, its: fast acting 0.5a 250v 5x20mm ceramic fuse

As always, thank you!
 
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Old 11-04-20, 11:00 AM
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Good find. Be sure not to use the meter in the current mode for voltage checks. The current mode puts a measured short across the probe wires. Anything over a half amp will blow that fuse.
 
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Old 11-19-20, 12:15 AM
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The old fuse was bad, however I'm still getting the O.F message even with the new fuse. Batteries are all testing good (1.5v each) and the new fuse is still testing as having continuity, as well as both the terminals the fuse goes into (no continuity if the fuse is removed).... Not sure of any other things to try...?

At least I have a second meter to try and troubleshoot the first one
 
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Old 11-19-20, 05:28 AM
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Did you check lead wires for continuity?
 
 

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