UT61D problems, advice needed on what to do next - Page 1
Forum section: electronics / general

author: tsmz
author_rank: Contributor
timestamp: May 21, 2011, 02:12:18 pm
content: After some consideration, I just bought a UT61D. I'm mainly interested in microcontroller stuff, so with its range of features, it seems to hit a price/performance sweet spot for about 50 Euros. I currently own a rather cheap DMM for general household use (measuring batteries, continuity, etc.), which has served me quite well for very basic measurements, but I was getting the feeling that something more sophisticated would be of advantage.But when I got my first unit, the V range measured about 300 mV without anything attached and the mV range just beeped and displayed "OL," which told me the meter was defective, so I sent it back and asked for a replacement. I bought it from a reputable big electronics seller in Germany, so warranty and support shouldn't be a problem. Today I got the replacement unit and while it "only" shows 3 mV without anything attached in Volts mode, the mV mode beeped at me again. I tried turning it off and on again, upon which the mV displayed values between 60 mV and 450 mV. Unless I'm getting something terribly wrong here, this one seems to be defective again (or they just "repaired" it incorrectly--who knows?)I'm currently pondering on what to do, so I would like your advice: I can still send it back for no reason whatsoever (within 14 days of the purchase), get my money back and think about buying another model (however, I don't really know which one, 50 Euros is about the price I'm willing to pay), or I could send it back again for further repairs/replacement. Is there anything else I could do to find out what's wrong with it? I'm not too keen on measuring anything with the current one I have, who knows what's defective there.

author: saturation
author_rank: Super Contributor
timestamp: May 21, 2011, 03:07:26 pm
content: I suggest you get something else. China quality control can be very variable and it comes in waves or orders [ like a supplier of parts received a bad batch or the same employee was assembling a set], and if you have 2 units bad in a row, chances are the same vendor you bought it from has a bunch of similar units as the stock they received.I believe Conrad is a popular seller of gear in Germany, and many decent Extech models are sold for under 50 Euros. They are fairly reputable and make better quality gear than Uni-T, IMHO.

author: Mechatrommer
author_rank: Super Contributor
timestamp: May 21, 2011, 03:15:03 pm
content: send it back, dont do anything to the meter. ask for different model dmm. dont ask for repair, just get another model or refund. thats my instinct saying from your story. unless... the shipping cost is high/problem.

author: Bored@Work
author_rank: Super Contributor
timestamp: May 21, 2011, 03:25:02 pm
content: You forgot to shorten the probes, didn't you?

author: saturation
author_rank: Super Contributor
timestamp: May 21, 2011, 04:22:45 pm
content: OY! I sure hope you did, tsmz before sending the meter back, I presume you know how to use a DMMs given you already have oe.Quote from: BoredAtWork on May 21, 2011, 03:25:02 pm

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 21, 2011, 05:07:38 pm
content: Quote from: saturation on May 21, 2011, 04:22:45 pmNo that's not enough ... just by accepting that you did a mistake..You will ask an public apology because you had insulted China again , with out a true reason.In the last 4 years Greece had five F16 crashed by mechanical damage.. all the 300.000.000 Americans are responsible about them.And so do not buy those .. or anything American.Do my words sound as crazy right now ? YES they do.Conclusion : when you blast China or other countries, your words sounds also crazy to me.

author: Bored@Work
author_rank: Super Contributor
timestamp: May 21, 2011, 06:19:00 pm
content: Quote from: Kiriakos-GR on May 21, 2011, 05:07:38 pmPlease don't forget to take your medication.

author: tsmz
author_rank: Contributor
timestamp: May 21, 2011, 09:06:56 pm
content: Actually, I didn't short the probes. With shorted probes, voltage is of course 0 V.I think I was utterly confused when the meter started beeping before measuring anything on the mV range, which is what it does from time to time. The "floating" voltage changes each time I turn the meter off and on again, which is something I can't understand.Could you please explain the source of this "floating" voltage? Thermo voltages and ADC noise should be much, much lower than a couple of millivolts. I've never had that phenomenon with other multimeters, especially not getting an "OL" indication before taking any measurements (which happens then and again on mV mode). I'd be quite interested to know more so I'll be able to assert whether the meter is defective or it's just an operator error.

author: Unknown
author_rank: Unknown
timestamp: May 21, 2011, 09:26:03 pm
content: Induced currents from electromagnetic fields? Some meters have a very high input impedance (eg. 1Gohm) at the low DCV ranges, this makes them much more sensitive to this. Reducing the loop area (bringing leads closer together, or twisting them) should reduce the inductive pickup. So should disconnecting the leads.

author: tsmz
author_rank: Contributor
timestamp: May 21, 2011, 09:31:08 pm
content: The problem even persists without any test leads attached.Input impedance for the 60 mV and 600 mV range is "Around >3000 MOhm", and "Around 10 MOhm" for 6V, 60V and 600V.

author: stl
author_rank: Contributor
timestamp: May 21, 2011, 11:32:30 pm
content: I have a UT61E and the same thing happens, this is not a malfunction! As long as the reading goes to 0V when you short the probes your DMM is just fine.This is due to the high-input sensitivity of the MM in the lower ranges.If you don't like the MM just get another one but don't do it because of this, or just because it's a Chinese brand.Chinese company's can do the worst but also some of the best products out there.FYI many DMM out there from company's like Volcraft, Proskit etc are just re-branded Uni-T and Mastech

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 22, 2011, 08:23:59 am
content: Quote from: stl on May 21, 2011, 11:32:30 pmI am aware of it , I own one of thoseProskit-Mastech, for almost 20 years.And I will totally agree with@Alm,next to my work shop, there is the large Mains transformer , that powers up all my square block.I know that it causes large interference , few years back that I was repairing CRT monitors,I could even see the interference , because it was disturbing the magnetic field of the CRT monitors on my bench.( That I had prior remove their shields , so to repair them ) .

author: Fraser
author_rank: Super Contributor
timestamp: May 22, 2011, 08:55:30 am
content: I own several UNI-T meters ranging from their cheapest models upto the more expensive ones in their range.When I first bought a UNI-T multimeter, I noticed that the display took longer to settle with open leads than my other multimeters but all my UNI-T meters seem to behave the same and all provide good accuracy when connected to the DUT. This is not a fault and has been stated, open leads will act as a virtually unloaded dipole antenna at HF/VHF frequencies so you will get spurious readings on low voltage and mV ranges. The beeping you are hearing is likely to be the auto range change indication as it switches to the most appropriate range for the detected input level. The beep on mV is likely indicating that the detected voltage exceeds the mV range maximum i.e. 'OL'. Again these are not faults.I do not know why UNI-T meters indicate more initial noise pick-up with a longer settling time than my other meters but it may be that they do not apply as much input noise filtering in their designs.If such behaviour annoys you then you need to look for another brand of meter. I can, however, state that UNI-T products are, IMHO, well made test eqipment with a few notable exceptions like their Bench meters. I purchased a quality Fluke 87 III and a very nice AVO megger digital multimeter and whilst these are beutiful pieces of test kit, I am still happy to use my UNI-T products as and when more convenient.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 22, 2011, 09:49:54 am
content: It is known that I favor the UNI-T mostly for the price / performance ratio ,in my country its a clear winner so far .About the behavior from model to model ,I would prefer additional given info , as example the year of the manufactured device and model.I own one UNI-T DMM that belongs at the inexpensive range of their products,it was made at 2001 ( UT30D ), and I am very forgiven to it , if the range switch needs some work ,so to start working properly.The latest and fresh UNI-T meters , are much better , from every aspect.And I would advice the ones who look to buy cheap , to not care just for the price,but to look for fresh made products 2003 or fresher.( Every UNI-T technical manual has an date to it , from there you can find the age of it )Some people think that every DMM baptized as industrial , its an bulletproof high class device .That's a lie , a big lie ...The industrial description translates to : that this DMM has additional functions useful to test electrical motors ..That's it , no magic , no bulletproof , no additional robustness ... its was just made to be used for diagnosis of electrical motors.If you need mechanical robustness , you pay extra just for it ..If you need robustness in the electronics of it.... you pay the premium of 400$I have start to believe that the people who works with electronics , they are very lucky,they could find easily an top meter for them, bellow the 200$ price range .The Industrial electricians are the unlucky ones,they have to get the premium tools , if they deal with the latest generation of electrical motors .Simply because those New motors have's very few things in common,with the electrical motors that we have see 20 years back.And I will use an favorite phrase of my own friend Safri as epilogue .Roger & Out ..

author: tsmz
author_rank: Contributor
timestamp: May 22, 2011, 11:42:09 am
content: Thank you all for answering my questions. This seems to be by design, thus my meter doesn't seem to be defective (probably not even the first one, oops), but it is extremely irritating nonetheless.I suppose the chipset used is responsible for this and it can be seen quite well in Dave's review (here). Honestly, I've never experienced readings as high as this without anything attached, so it was (and still is) quite irritating. Especially when the meter starts beeping right away as soon as the mV range is selected.I'll most likely be keeping the meter anyway, as the price/performance ratio seems reasonable. The autorange is a bit on the slow side, though and the continuity tester could be just a bit sprightlier, but I can live with that given the price.An interesting difference compared to the unit Dave reviewed: I own the "GS" version (stands for "tested/certified safety" in German), PCB marking "100207-4(GS)", which features much larger fuses: A rather long ceramic one for the mA input jack with no easily discernible marking and a big ceramic fuse (Littlefuse KLKD 10) for the A input jack. Also, the component "SG1" near the input protection (here) has been placed (looks big and cylindrical, possibly a gas discharge tube?)

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 22, 2011, 02:38:26 pm
content: Quote from: tsmz on February 20, 1974, 03:34:12 pmYes those Germans, loves the extra regulations , and so you got a DMM that it was planed to be sold in Germany.That's nice ..I use to buy batteries for my motorcycle , from the German market too,because their extra regulations, forces the Asian makers to deliver in to Germans, better made products.( safety & materials )

author: gobblegobble
author_rank: Regular Contributor
timestamp: May 23, 2011, 02:21:44 am
content: If you're troubled by the low input impedance paired with a high sensitivity, you could always attach a resistor between the leads to drop the input impedance back and to lessen the effect. Just don't go near higher energy circuits with that if you do.As for the electricity surrounding us, well let's just say I can get my "non contact voltage detector" get lit while standing in a middle of the room and touching nothing. Hope I don't get brain cancer from all this.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 23, 2011, 02:28:08 am
content: Quote from: gobblegobble on May 23, 2011, 02:21:44 amI bet that you have an AM transmitter under your bed.Or some one else in the family.

author: gobblegobble
author_rank: Regular Contributor
timestamp: May 23, 2011, 02:44:22 am
content: Quote from: Kiriakos-GR on May 23, 2011, 02:28:08 amAre you stalking me?And no AM transmitters, just very old CRT equipment.