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Products => Test Equipment => Topic started by: piggy82 on May 28, 2015, 05:57:06 pm

Title: what is wrong with my meter?
Post by: piggy82 on May 28, 2015, 05:57:06 pm
Hi, sorry for asking a newbie question. I recently purchased an Amprobe Am-270 from ebay and it tested vol/resistance pretty good. However, I noticed that it does not test current properly. Every time I turn the knob to A, mA or uA setting without lead touching anything, there is an initial reading about 7mA or 70mA and it gradually drops to 0mA in about 5 to 20 seconds. And if I use the meter to test current (like a simple battery+led test) there does not seem to be any meaningful reading at all other than the weird 7mA-->0mA drop, the LED does light up though.

I tested the fuses and the resistance seems to be as low as ~1 Ohm, battery is new with 9.3V.

Does this mean the meter is dead?...

Thanks

Title: Re: what is wrong with my meter?
Post by: electr_peter on May 28, 2015, 06:11:31 pm
Hello,

What you describe certainly sounds worrying, DMM should not behave this way in normal conditions.
Before jumping to the conclusion, could you check few things:Do you have(or can borrow) other DMM with current measurement capability? Connect these two meters in series, run simple test with resistor and battery.
Title: Re: what is wrong with my meter?
Post by: piggy82 on May 28, 2015, 06:47:15 pm
Holy cow :wtf:...Thanks a lot for your reminding and it turns out it to be set to AC current. I guess this is where I missed: on the manual it says:

uA, mA, and A current Functions
Default at DC. Press SELECT button momentarily to select AC

It appears to me that the word "momentarily" suggests if I turn off the meter and turn it back on it should reset to the default.

So I didn't pay attention to the AC/DC setting as I assumed it should be default to DC. Anyway it turns out if I select AC, it will stick to it even if I turn it off! And somehow it was set to AC current before probably by an accidental pressing the SELECT button. I should have paid more attention to the meter itself. Luckily I didn't fry anything.

Thank you again for the prompt reply and suggestions :)
Title: Re: what is wrong with my meter?
Post by: Muxr on May 28, 2015, 07:01:31 pm
Actually I was going to suggest checking that you're set on DC current, but then I looked at your meter's picture and noticed DC was default in current mode. So not sure how you missed that  :o

Even my 87V counts down on the last digit when in AC current mode with no leads connected. I think it's the feature of true RMS doing its magic when you first switch.
Title: Re: what is wrong with my meter?
Post by: piggy82 on May 28, 2015, 07:03:39 pm
Quote from: Muxr on May 28, 2015, 07:01:31 pm
Actually I was going to suggest checking that you're set on DC current, but then I looked at your meter's picture and noticed DC was default in current mode. So not sure how you missed that  :o

Even my 87V counts down on the last digit when in AC current mode with no leads connected. I think it's the feature of true RMS doing its magic when you first switch.

It was truly my carelessness:) Thanks.
Title: Re: what is wrong with my meter?
Post by: retiredcaps on May 28, 2015, 07:07:03 pm
Some Brymen meters, the Amprobe AM-270 is a Brymen rebadge, remember the last setting you used even when turned off.
Title: Re: what is wrong with my meter?
Post by: electr_peter on May 28, 2015, 07:14:05 pm
Quote from: piggy82 on May 28, 2015, 06:47:15 pm
Thank you again for the prompt reply and suggestions :)
I am glad you found my reply useful.