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autoranging multimeter micronta 22-193

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alpibucky

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Hello,

My old micronta 22-193 is faulty. The LCD gives BATT while the batteries are good. The readings on DC are faulty : 0,6 V instead of 1,5 V.
The main IC is a SXC 1901F of which I do not have got the datasheet.
Does anybody have this datasheet or have the same trouble with this autorange meter ?

With my best regards,
 

BradtheRad

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I've dug inside my digital meters in a constructive attempt to fiddle with adjustments.

1.

Most likely your meter (like mine) has a trimmer potentiometer somewhere inside, which the factory adjusted to set the meter to read correctly.

Pots are prone to develop a bit of tarnish on the internal contacts.

If you're in an experimental mood, see if you can find the trimmer and bring your readings back up to the proper value. You may need a tiny screwdriver.

If you can apply a known reference voltage, then you can dial to the matching reading. It might be necessary to work out scratchy glitches in the pot.

The same measuring circuit (ADC) that reads your battery is probably the same one that reads your probe leads.

Can't explain why your meter got out of adjustment suddenly, if that's what happened.

2.

There's also a chance something has gone bad to start causing a major drain on the battery. It results in a lo-bat alert. Readings would be affected as well. However when you take out the battery and test it, it reads good because it's not being drained any more.

Therefore use a good meter to monitor voltage of the battery as it is powering the faulty meter.

3.

Are any of the units ranges giving good readings? Then the internal adjustment might not need to be touched. Instead something might be wonky in the switching knob, when you use certain ranges.

4.

Check your fuse. Corrosion or galvanic action may have caused it to develop substantial resistance. Use another meter to measure for any voltage drop across the fuse while the ailing meter is on. Only the tiniest voltage drop should be seen. If it's substantial then your meter's circuits are underpowered.
 

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