Tenma 72-8150

If you have tried different leads, capacitors, the only thing I can think of is perhaps resetting any settings (if there are any), perhaps removing the battery for a while and trying again.

However, it's probably more likely that the meter was somehow damaged - perhaps by ESD or by connecting a charged capacitor for testing. Most capacitance testers cannot handle charged capacitors or testing "in circuit" when voltages are applied. If it is still in warranty and you are convinced that you didn't do anything to cause it to fail, you might consult with your local element14 branch in regards to support or warranty.

Unfortunately, as this is the community forums, we (mostly) do not work for element14 and are not involved directly with the selling of products.

- Gough

Warren,

I know it may sound stupid, but the first thing a customer service person asks is "Is the unit plugged in?"  I know this is a battery operated unit, but could the battery need replacing?  You didn't mention whether you check this.  I once knew a friend who had one of the first TI calculators that when the battery was low it didn't have a low battery indicator, it just gave the wrong answers.  Let me know what you find.

Regards, Gordon

Checked battery and was ok.  Replaced it with a new one.  No change.  I guess now is time to go to the dump.  Thanks for your reply!

Looking at the manual for this, it indicates that there is fuse protection on the circuit, have you verified that this is ok?

It also gives a specification of the output for these tests, do you have a frequency counter or oscilloscope that you could use to see if the test output is within specification?

Kind regards

Hi Warren,

One other thing to try (although its a long shot) could be to rotate the dial a few times.. normally there are a few switch wipers underneath it, and perhaps one isn't making correct contact and some division by 2 isn't being made : ( I only suggest this because I used to have a UNI-T multimeter that once started to give bizarre readings that were related to the input, and it was the switch wipers.

I don't know if it is the case here (it may just be a duff unit that eventually failed - I had an insulation tester came with a manufacturer fault), but I've always thought that capacitance meters should come with a huge warning on the front panel reminding the user to discharge first, because it is an occasional use tool for some lines of work, and those are the situations where people can forget once in a while. It seems like a usability issue, that they don't do that. I printed a label for mine on the front panel to remind me. Since I'm used to checking multimeter test leads before connecting to a circuit, that means I'm used to checking the front panel of any device with test leads, so I'm trying to reassure myself I'm likely to see a large label - I hope! : (

Did you check the ADJ knob to see if it changes the results? Also, are your test clips in good shape? I had this issue with my LCR meter where flaky contacts caused erratic measurements.

This capacitance meter is a rebranded Uni-T UT601, but unfortunately I couldn't find schematics.