Flaky DMM on DC Voltage

[Citroënbender]

My meter is a good 15 years old, it cost me $80 back then. Auto-ranging with extras of temperature, capacitance, inductance, transistor testing. I’ve barely used the last two aspects but otherwise it gets a flogging. The temperature (with k-type probe) is great for thermostat checking on the bench.

Lately it’s become increasingly unreliable when measuring DC voltage. It has long had the odd vague-out on resistance or continuity but usually twisting the dial a couple of times and/or pressing Reset, fixes this. DC volts, though, unless it’s a strong source it is no longer giving a sane reading.

Technology price-points have shifted, I could replace it for $70 with a meter that does everything the same except inductance and transistor checking. Before I do that - has anyone experienced similar malfunction and resolved with a repair?

[cs123]

Perhaps change the battery, clean the terminals with a cotton bud and isopropyl in case you have some oil or gunk in there, check the range switch too.... then bin it. If you can't trust it, you can't trust it.

Funnily enough my worst meters for reliability have been Fluke. The $50 to $150 meters seem to go forever.

[ford71V8]

Have you swapped out the leads for known reliable ones? Even a second set might give you a clue its not the meter (edit - though it looks to read non-DC without issue)

[aussiblue]

Have you opened it up and:

Checked for dry joins especially around where the sockets for the test lead are solder to the PCB;
Checked the tracks of the selection knob are making good contacts with the knob and are not worn away;
The batteries have not leaked and corroded anything; and
there are no smoke marks or other indications of component failure?

[Citroënbender]

Have pulled it down and visually checked.

All solder joints look fine. Processor has black epoxy security, this does not seem to be chemically decomposing.

The double-ball dial detent has been weeping grease onto the circuit board, possibly contaminating the wipers and their tracks. I lightly buffed the wipers with grey Scotchbrite, thoroughly cleaned them and the tracks with wax-and-grease remover, cleaned the LCD signal contacts with alcohol, reassembled. Just another evening of stuff you do when TV isn’t in your life…

Now to test it!

[Citroënbender]

Well, it’s definitely no worse. I really need daylight to confirm - but it may be fixed.

[Captain Stubing]

I have a Digitech meter that doesn’t read DC volts at all now. Luckily I have replaced it with one that does more, like reading frequency. I’m not sure what to do with the faulty meter… label it AC only? Or for continuity checks , and AC if you dare. Either way I might make a DODGY label for it.

[Citroënbender]

Originally Posted by Captain Stubing

Either way I might make a DODGY label for it.

Sounds a very modern meter; it has replaced facts with opinions.

[Itsme]

Why would you bother with it, bin it and get a quality replacement.

[Citroënbender]

I’m pretty tight with some things. It doesn’t provide data which directly affects health and safety items, the most common use is continuity/resistance followed by DC volts. So, if it’s been scrubbed up sufficiently to rely on for these tasks - I’ll save my $69 for now.

[Itsme]

Originally Posted by Citroënbender

I’m pretty tight with some things. It doesn’t provide data which directly affects health and safety items, the most common use is continuity/resistance followed by DC volts. So, if it’s been scrubbed up sufficiently to rely on for these tasks - I’ll save my $69 for now.

Fair call; but for me accuracy is a must otherwise inaccurate readings does not cut it when it comes to testing circuits & components.

Cheers

[zilo]

Digitech? .... am surprised it lasted this long....