Toasted Uni-T UT61E - Page 1
Forum section: electronics / testgear

author: Bryan
author_rank: Frequent Contributor
timestamp: April 27, 2015, 09:50:34 am
content: All:Was measuring the voltage of a ozone generator , roughly around 300VAC. Looks like it has toasted the meter. Pulled the battery as I thought there might be a reset possibility but no luck. Showing ohms on DC voltage reading, capacitance on AC , and ohms on any of the current selections except the 10A. Weird.

author: peter.mitchell
author_rank: Super Contributor
timestamp: April 27, 2015, 09:58:56 am
content: QuoteQuoteChoose one.

author: smjcuk
author_rank: Frequent Contributor
timestamp: April 27, 2015, 09:59:55 am
content: Can you peg a digital meter?

author: Bryan
author_rank: Frequent Contributor
timestamp: April 27, 2015, 10:06:26 am
content: I guess I did.But I thought it was rated to 700VAC or 1000VDC, at least according to the spec sheet.

author: Wytnucls
author_rank: Super Contributor
timestamp: April 27, 2015, 10:06:50 am
content: Open it up and look for damage on PCB traces or ICs.

author: Ice-Tea
author_rank: Super Contributor
timestamp: April 27, 2015, 10:09:17 am
content: Ozone generators? Are those not simply voltage doublers up to a few kV?

author: Bryan
author_rank: Frequent Contributor
timestamp: April 27, 2015, 10:11:22 am
content: Ya, maybe right on that, maybe the reading of meter reading 260VAC was much much more..

author: MatthewEveritt
author_rank: Unknown
timestamp: April 27, 2015, 10:18:07 am
content: I thought ozone generators produced DC with ripple? If so measuring AC would only give you the ripple.

author: Wytnucls
author_rank: Super Contributor
timestamp: April 27, 2015, 10:18:23 am
content: Several megawatts of electrical power may be installed in large facilities, applied as one phase AC current at 50 to 8000 Hz and peak voltages between 3,000 and 20,000 volts. Applied voltage is usually inversely related to the applied frequency.

author: LA7SJA
author_rank: Regular Contributor
timestamp: April 27, 2015, 10:21:37 am
content: The model of Ozone generators I used to repaire many years ago messured 11KV 50Hz AC on the "tubes". That could explaine the damage.Johan-Fredrik

author: MatthewEveritt
author_rank: Unknown
timestamp: April 27, 2015, 10:27:13 am
content: Either way I think we can agree that cheap multimeters don't work so well after you try to turn part of them into ozone.

author: LA7SJA
author_rank: Regular Contributor
timestamp: April 27, 2015, 10:53:01 am
content: Quote from: MatthewEveritt on April 27, 2015, 10:27:13 amI think we can agree thatcheapany multimeters don't work so well after you try to turn part of them into ozone.Johan-Fredrik

author: mzzj
author_rank: Super Contributor
timestamp: April 27, 2015, 11:05:37 am
content: My friend fried my UT61E also with high voltage. I was able to trace the problem back to some tiny dual diode and main the chipset, after found I found out that the main chipset was busted I tossed the meter to bin.Welcome to the club:https://www.eevblog.com/forum/repair/uni-t-61e/

author: rsjsouza
author_rank: Super Contributor
timestamp: April 27, 2015, 11:19:22 am
content: Quote from: LA7SJA on April 27, 2015, 10:53:01 amAgree with that. I fried my reliable DMM of 25 years when inadvertently tied it to the 3kV output of a ozone generator. Anything will go down when pushed beyond the specs...

author: Lightages
author_rank: Unknown
timestamp: April 27, 2015, 12:12:16 pm
content: Been there, done that:

author: cdev
author_rank: Super Contributor
timestamp: April 27, 2015, 07:09:59 pm
content: You zapped the meter with high voltage.Air ionizers (as used in electrostatic air filtration) generate voltages at several thousand volts (but almost no current) and "ozone generators" (very much discouraged because ozone is actually dangerous)produce even higher voltages.

author: mcinque
author_rank: Unknown
timestamp: April 28, 2015, 11:49:31 am
content: What you expected with HV? It's not a surprise you toasted the DMM. You would have toasted any other "600VAC maximum input" DMMs.It's not a matter of "cheap" DMMs, it's a matter of maximum input allowed.

author: paulie
author_rank: Frequent Contributor
timestamp: April 28, 2015, 12:13:08 pm
content: Quote from: mcinque on April 28, 2015, 11:49:31 amActually it IS a matter of cheap DMMs.Better to blow out one of those than one costing 5x or 10x more. Or 100x more. That's why my Fluke sits on a shelf under half inch of dust. Too big and risky. I'd regret buying it except it was a gift and I didn't actually buy it. 99% of the time one of my $5 DT-830d does the job and if I need to read frequency or capacitance the $12 UT136b. But then I'm one of those rare individuals who uses gear to measure stuff, not just impress the gang.

author: MatthewEveritt
author_rank: Unknown
timestamp: April 28, 2015, 01:00:46 pm
content: Quote from: paulie on April 28, 2015, 12:13:08 pmNot to mention, of course, that there are expensive units designed to measure these sorts of voltages. I'd generally expect an expensive meter to fail in a more repairable way too (sacrificial protection as opposed to setting on fire or whatnot.)Still, hopefully someone learnt something, and maybe we get to see images of toasted meters.

author: paulie
author_rank: Frequent Contributor
timestamp: April 28, 2015, 03:41:53 pm
content: I would like to see a photo too and find what component was actually blown.It's hard to believe a mid range meter like that could sustain damage with such low current involved. With my $5 meters more than once I've stupidly attempted to measure 800-900vdc geiger counter supply on a variety of incorrect settings in addition to quarter million volt static sparks and yet to sustain damage. At least not that way.The only way I've managed to screw one up was trying to check voltage of a high power source (ie car battery) on current range. And that was easily fixed replacing the fuse (usually with #40 magnet wire). I have seen literally dozens of noobs do that too. I suspect this may be the real cause of bricked meters in more cases than are admitted.

author: Rick Law
author_rank: Super Contributor
timestamp: April 29, 2015, 12:23:52 am
content: How about putting the remains of the UT61E on eBay, some may like to buy the "for parts only".Any money is better than just chucking it into garbage.

author: mcinque
author_rank: Unknown
timestamp: April 29, 2015, 11:21:49 am
content: Quote from: paulie on April 28, 2015, 12:13:08 pmAny meter can be killed if you don't follow its specs.Follow the maximum input specs of your instrument and you will not have any issue of this kind.Quote from: paulie on April 28, 2015, 12:13:08 pmThe real problem is that you MUST know at least what voltage range you're going to have on the points you're going to probe. Only by knowing BEFORE how the device you're going to probe works, you will be safe.If you don't know what to expect (or you ignore the maximum input of your instrument) and you're going to probe it anyway,it's another issue (a big issue IMO).Quote from: paulie on April 28, 2015, 03:41:53 pmYou can kill many components with high voltage, even with an extremely low current. I don't think this is uncommon.

author: Rick Law
author_rank: Super Contributor
timestamp: April 29, 2015, 04:08:42 pm
content: Quote from: mcinque on April 29, 2015, 11:21:49 amI am also sure most here already knows this. I recall an advice I was given about a zillion years ago:"When you don't know what you are measuring, always start with the HIGHEST VOLT measurement first..."I am sure that wont save every bad day, but that should save some bad days.As for me, I often get in trouble is when I try to finish something when I was way to tired to know what I was doing. Too tired even to know I should not be doing it... zap... smoke... oh, darn...

author: SeanB
author_rank: Super Contributor
timestamp: April 29, 2015, 04:56:18 pm
content: Was looking at my cheap meter yesterday, cleaning the range switch ( noisy) and on the back is a sticker warning you to turn to manual volts if measuring above 400V. Not going to happen, I use it for low voltage only, as it also has no input protection other than a PTC, and even then some ranges are switched before this....... Still I like it, as it has a large display, and does capacitance somewhat reasonably. Continuity though is at best described as somewhat delayed, but still a good little $10 meter. Had it since 2003, and haven't killed it yet, though I do have a 10 pack ( half used) of fuses inside it for those occasions.

author: Bryan
author_rank: Frequent Contributor
timestamp: May 02, 2015, 09:39:02 am
content: Well took it apart and couldn't find any carbon traces or damage of the sort, not worth poking around. Time for another. Been awhile since I looked at budget DMM. Is the Uni-T 61E still a good buy or anything else new or on the horizon.

author: Bryan
author_rank: Frequent Contributor
timestamp: May 02, 2015, 09:40:52 am
content: Quote from: cdev on April 27, 2015, 07:09:59 pmYes, well aware of the dangers of ozone. In my case it's just a small unit to add ozone to a aquarium.

author: cdev
author_rank: Super Contributor
timestamp: May 03, 2015, 01:36:32 am
content: Quote from: Bryan on May 02, 2015, 09:40:52 amis that to reduce bacteria or something?

author: Bryan
author_rank: Frequent Contributor
timestamp: May 03, 2015, 11:22:29 am
content: To raise the ORP and help remove dissolved organics. Does help with cynobacteria outbreaks. Ozone in salt water aquariums was very popular years ago but somewhat considered not as practical anymore.

author: Lightages
author_rank: Unknown
timestamp: May 03, 2015, 11:51:24 am
content: Quote from: Bryan on May 02, 2015, 09:39:02 amIt is still a good buy if you want the 22000 count and PC connection. If you want something with better input protection, back light, temperature but with less rated accuracy and o PC connection then I can recommend the UT139C.