Return of the UNI-T UT139C Part 2 of 2

[@mdzacharias]

Picked mine up for $10.00 "new, other". Pretty happy with that. Won't replace any of my Flukes, but I think it's a pretty neat little meter. I really only do audio for the most part.

[@paulb4496]

Thanks Joe, I just ordered one for a bench meter only. I have a brymen 235 for 240 and 460 volt testing. I do commercial HVAC. I enjoy all your review videos.

[@KiR_3d]

Wow! Very complete overview! :) I was surprised how well the 139C is protected.

[@joesmith-je3tq]

Its more robust than most of the UNI-T products I have looked at.

[@oratrovovortaro]

Thank you very much! Definitely, the best test on youtube.

[@joesmith-je3tq]

+parab00m Thanks! Glad you enjoyed it and hope you found it helpful.

[@MarcoFranceschini1971]

Great as usual Joe...i bought last week one UT139C...

[@park8023]

Hi Joe, dtm0660l chip is affordable now for a replacement, about $7 on Aliexpress, and adding missing transistors in the upper side will certainly help to protect the chip, they are coupled to the IC and the four 2.5M (R1a R1b R1c R1d) wich are in series with the "main", don't really know what the two unpopulated other one where supposed to do ! PTC1 was dammaged in the first test, some modifications in this area could probably help it to pass the 5Kv ! (Uni-t added one more PTC in the S version and the PCB traces are wider).

[@joesmith-je3tq]

No doubt that EVERY meter I have looked at could be improved. That's a job for the manufactures. Wouldn't you expect there to be at least two more PTCs in series to create the low impedance function? Or are you suggesting that this added PTC has something to do with making the meter more robust? Hard to believe that anyone would come to that conclusion. If so, trace it out and show me. I can however believe they skimped on the low impedance mode and did it with one PTC. My guess, the same old 5mm package they like to use. Personally, I don't see this as an improvement. Like I said, if I am wrong (I'm just guessing) about the added PTC, show me.

[@park8023]

​@@joesmith-je3tqYou're right, I relied on the 139C (mine) and I didn't pay attention that they had integrated the Lowz function in the "S" version, but nevertheless they modified the input by putting a common PTC for the 10M and 900k. For the "C" version the 900k pass only has two MOVs comming after !? And since they didn't have populated the transistors pairs, chip isn't protect at all against high voltage in this range... I found documents that will probably interest you, or simply help me answer my questions, if you wish ! uni-trend.com.cn/uploadfile/2018/0824/20180824024302224.pdf uni-trend.com.cn/uploadfile/2018/0823/20180823095727835.pdf There is at least one error on the diagram of the 139C, RV2 on schem = RV4 on PCB and RV2 (the fourth omitted on the diagram) is connected between PTC2 and RV3 on PCB. In your opinion is it wise, for the previous "C" and "E" versions, to add the omitted transistors (upper area is for 10M and lower for 900k) and connect the first 300k resistor between PTC2 and MOV2, as shown in the diagram of the "S" version, or will it be at the cost of a precision loss ? Safety, precision or simply bad idea ! What is your opinion ? Thank you for what you share, I'm learning a lot !

[@joesmith-je3tq]

@@park8023 My opinion is to let the designers, manufactures and test houses do their jobs. They should be the experts in the industry. These standards are for the safety certifications. Again, nothing to do with what I am showing on this channels. I would have no way of knowing what the effects are of making ANY change to a design. My guess is the outcome could be bad. Really, if the goal is to have better equipment, just buy it. It's never wise to think your an expert in the area of safety and it's always a bad idea to start making changes to a device with a safety rating.

[@fly-lucky]

Just curious about running the test bench series from bk precision? Set of four meters in the $200+ range. Models 391a, 390a, 389a, and 388b. I looked at your spreadsheet I didn't see theses meters. Also what are your thoughts on the bk meters you tested to date.

[@vageer476]

Nice review. Mr. Joe, how about UNI-T UT139E multimeter? The manufacturer claims it's spike protection is about 6000V. I'm waiting for your review 😀

[@coskunvelioglu]

WHAT IS THE REASON I COULD NOT MEASURE THE OSCILLATOR IN Hz STAGE WITH UT139C MODEL MULTIMETER? UT61C MODEL CAN READ 32.768 FREQUENCY VALUES. IS IT POSSIBLE TO MEASURE Tuning-fork crystal used in a modern quartz watch WITH UT139C?

[@petermatthews2095]

Great testing. You seem to be harsh on the 139C as it survived up to 3.7 KV, costs less than $50 has a good sensitive NCV (far better than the Amprobes 510 & 530), back light, 6000 count (compared to 4000 on the Amprobes)and has good continuity (faster than the Amprobes). In spite of this you have great praise for the 510 purely because it survived up till 5.8 KV.Most people, technicians will not go over 1000volts (if that) so does it really matter when using a meter how much it survives above this figure. I realise you rate the robustness very highly and have had bad experiences with the UNi-T 61D/E's, but the 139C definitely is different and is "safe" as regards it's operating instructions. In England I can get the 139C for £28 (Around $40) and overall it seems a better buy than the Amprobes taking everything into consideration.I would welcome your reply.Peter

[@joesmith-je3tq]

+peter matthews As I have stated several times, these tests from the beginning have been about how electrically robust the meters front ends are. This is why the Fluke 101 was ranked the highest of the first set of meters I looked at. It has nothing to do with their features, how they look or handle a drop test. If you are interested in these types of reviews, there are countless other videos you could watch. As for safety, I will say it once again because you seem to have missed it. I am not a accredited lab. If you have interest in knowing if a meter is safe that has not been certified by an independent party, you would have to have it done. Safety and robustness are not the same thing. The 139C earned it's place in the spreadsheet not because of how the UT61D/Es performed or how UNI-T products have performed in general. It's placed there because this was it's failure point when tested the same way with the same equipment as all the other meters. "Most people, technicians will not go over 1000volts (if that) so does it really matter when using a meter how much it survives above this figure" Maybe use Google?

[@petermatthews2095]

+joe smith OK Thanks!

[@joesmith-je3tq]

It's strange you would feel that way. The ONLY meter I have looked at that was made in the USA was the Fluke 87V and it did very poor.

[@artblank9162]

robustness against hv spikes and transients is what is demoed in this video. not the pretty red skirt it wears, how sharp is the display, or how shiny the plastic case is. robustness is somehow a sibling of SAFETY. if it does not pass them standards, it means it aint fit for a james bond super electrician type of work. this is to make aware of them folks who are curious on how these meters will perform in work areas where the SUPER FAST SPIKES CAN REACH UP TO 5 KV...or maybe more. these pointy waveforms are real. we've seen them destroy even hi end meters like fluke. and ive seen it also burn one of the 139c that i had before. it really flamed itself into plastic ice cream. good thing i hanged it up on an insulated post. and i think, i mean i really really do think, if i was HANDHELDING that THING that time, ummm a mumbo jumbo blister? YOU THINK?

[@artblank9162]

robustness against hv spikes and transients is what is demoed in this video. not the pretty red skirt it wears, how sharp is the display, or how shiny the plastic case is. robustness is somehow a sibling of SAFETY. if it does not pass them standards, it means it aint fit for a james bond super electrician type of work. this is to make aware of them folks who are curious on how these meters will perform in work areas where the SUPER FAST SPIKES CAN REACH UP TO 5 KV...or maybe more. these pointy waveforms are real. we've seen them destroy even hi end meters like fluke. and ive seen it also burn one of the 139c that i had before. it really flamed itself into plastic ice cream. good thing i hanged it up on an insulated post. and i think, i mean i really really do think, if i was HANDHELDING that THING that time, ummm a mumbo jumbo blister? YOU THINK?

[@TheWolfmanG]

Thanks for the through review. This $50 is perfect for my at home/auto use. AMPROBE is twice the price. So I'll pass on that.

[@mortrek]

You deserve more subscriptions and views. These videos are great. Also I ordered this uni-t. I hope that it works out. I don't really work with high voltages so I'll probably be fine...

[@joesmith-je3tq]

Once this one failed I did not replace it a third time.

[@mortrek]

hrm. Well, it actually seemed to do fairly well in your testing until you got to the higher voltage transients, right? I'm trying to replace my mediocre TPI 440 and don't want to spend a lot. I also considered Amprobe, but it's more expensive and didn't seem much better in many respects. I may buy a more expensive one if I hadn't just spent a bunch on a new scope as well... that eevblog branded Brymen does seem pretty good for the money...

[@joesmith-je3tq]

You know where the spreadsheet with the data is stored, right?

[@mortrek]

yeah I looked through it. I guess I'm just looking for a sub-$50 scope with good accuracy, true RMS, and a list of other features that interest me, and the uni-t fits that pretty well. reliability and safety are important, but i work with electronics and low voltages. if I need to measure mains often, I'll probably get one of those super stripped down flukes or something. I doubt my wife would appreciate me putting a few hundred bucks into a multimeter for hobby work.

[@ulanbat0r]

Much better videos of the 139c than the first one you made. But i still don't get the point of applying 5kV to a meter which is rated for 600V ... Thanks anyway

[@joesmith-je3tq]

+ulanbat0r You are not alone in your point of view. You are correct that the manual for the UT139C states the "Maximum input voltage: 600 Vrms". To be clear, Vrms would be the same for both AC and DC but not at all for the waveforms I apply during these tests. The part you appear to not understand is that many of these meters are specified to meet a certain IEC standard. In the case of the UT139C, the manual states "Safety Standard" IEC/EN 61010-1: CATIII600V" This is the first version of the standard and has a maximum of 6000 Volts using a 2 ohm source impedance. The waveshapes (open/shorted) are called out in the standard along with the five +/- transients. Now all that said, I am not testing to this standard. The width of the pulse being applied is double for the 6KV and less tests. The other major difference is I greatly limit the energy available to the meter for safety reasons. Typically this has been less than 10 Joules but I have ran some near 20 Joules. The reason for the tests is simple, to find which meters are more robust electrically than others. This is why they are all tested to failure (for the most part). I keep a spreadsheet on DJs EEV blog site that you can download a quickly see the overall results of these tests. UNI-T meters as a whole have been some of the worst I have looked at. The Chinese made Flukes I have tested have by far been most robust. Hope this helps.

[@kostaskritsilas2681]

Because when you are testing line voltages, it is entirely possible to have a transient come onto the AC line. You can take issue with the transient being 2KV, 3KV, or 5KV, but the IEC standard (61010) for Class III is 5KV minimum withstand voltage. This is what Joe is testing to. His transient generator closely follows the IEC specified waveform. If you have an issue with the 5KV level, take it up with the IEC.

[@MihaSun]

Good day, I would like to ask you if the surge protection are good for anything for protect laptop or other device, or is it just a myth or just advertising to sell this product? Thanks Thanks

[@joesmith-je3tq]

I've had people as me about AC line devices. I have no way to evaluate them. I would assume that manufactures of AC powered devices design them to withstand some of the basic transients.

[@MihaSun]

@@joesmith-je3tq Thanks very much ,from Italy

[@Sloxx701]

Judging by the comments, I'm not sure why people don't understand the purpose of HV transient testing on a multimeter. No, no technician is going to be measuring 6kV with a handheld multimeter (no shit), but that's not the point. It's advertising itself as CAT III, it should be tested to that standard. Not that I would believe it from Uni-T, they are notorious for putting whatever CAT rating they feel like on their meters.

[@dfigueroa903]

Looking for one with quick continuity response ... I head this one is good..

[@MalagasOnFire]

Well the manual states well to not rotate it but in real life you might leave the multimeter in ohms mode and someone is going to read volts on the mains and BANG.. Well I had an mastech MY-64 for basic electronics in home and just a measure from a electric mosqito zapper ( 2kv) ruined this multimeter. Than i bought an ut50b ( manual but fast measurement) and it passed this test and so far from 2010 till now still works for homemade electronics and ocasionally some mains voltage, which the UNI-T i think is best suited. For outdors and industrial better be with some fluke, bryman as stated by this video.

[@doctorazizli]

Joe - can you please explain what 5k volts test mean? and what model of Brimen are you showing here?

[@joesmith-je3tq]

Ramin, my Brymen is a BM869s. I picked up the EEVBLOG rebranded BM235A as well. I assume you searched Google and maybe saw some of Flukes testing and wonder what I am doing different. I have made a few videos where I talk about it. This is the last one I made where I show the new generator in operation. kzbin.info/www/bejne/hnu3e32lmaqor6M

[@joseluiscontrerasislas5453]

Hello: Joe I have only one question about UT139C comes with backlight?

[@joesmith-je3tq]

yes

[@samanelectronics]

i got ut 139 c above six mounts a go. now voltage display as multiply by two & ohms auto range and decimal points error :( . i used ut 60b meter six years. ut 139 c is suck.

[@dfigueroa903]

Morning In my years in engineering... I call this, old school testing... In my opinion, thus is the best testing, hands down... I was taught by people like you..... I have all respect in this process of testing.... I need a meter to carry around ( purchased a uni-T 139B) ... I do residential electrical repairs and car customizations now do to my injury years ago... Yes I have good meters ( But) need one with a good continuity checker (. Heard this one is good) .. Question is, is it?????? I see you video the uni- t 139 c , are they the same spec wise...????? Would like to know...

[@joesmith-je3tq]

I would say the continuity test is a personal preference. I do have data for many of the meters I have tested stored on-line in a spreadsheet. This includes the continuity testing. You may find a link to it in the description. You could run some tests to see how yours compares but IMO, it really comes down to what you need, not how it compares with another meter.

[@dfigueroa903]

The 139c and 139 b have the same over current specs???

[@joesmith-je3tq]

@@dfigueroa903Over current specs? If you are asking if the b version is as electrically robust as the c version, I would have no idea. If you are asking if they have the same accuracy/ranges/resolution in the current modes, I would just compare the manuals.

[@dfigueroa903]

joe smith would like to see you do a review on the 139B.....

[@joesmith-je3tq]

@@dfigueroa903 I doubt I will look at any more UNI-T products. I've looked at a fair number of them and they never perform very well in my testing. If they release an improved version of the UT181A, I will have a look at it.

[@besllu8116]

AN8008 vs UNI-UT139C? Which is better and more robust?

[@joesmith-je3tq]

In the description is a link to the data I have collected.

[@besllu8116]

Thank you, missed that.

[@mianali1199]

Hi Is there any way to upgrade input protection on this multimeter uni-t ut 61e? There is a way plz guide me to do it .

[@joesmith-je3tq]

I would not say I upgraded the input protection on the UT61E. It may be more robust now but could be a lot less safe. Once the second 139C was damaged, I did not replace it.

[@mianali1199]

joe .thanks for your reply.i have seen that you repaired unit 61e once.in this meter there are 3 ptc 400 to 1100volts according to the data sheet 5mm.there is empty place for 4 mov.can we put there movs and if we need which one you advise .also advise if we need to replace the ptcs and fuses.

[@joesmith-je3tq]

If you need a better multimeter, I suggest buying one. Attempting to modify one is a bad idea. If you're a beginner, it's just being stupid.

[@haralambosx]

Hello. Glad U found your channel. I was thinking of buying a meter. I am a simple amateur that just tinkers with computers as a hobby. I checked two meters the UNI-T 139C and Mastech MS8260G. Could you give me your opinion about the two of them I found them for 35 euro. Thank you.

[@joesmith-je3tq]

Sorry but I have never looked at the Mastech MS8260G that you are asking about. I don't have a lot of info on the 139C other than what I show in the videos. My meter of choice is still the Brymen BM869s.

[@claysonwebster1622]

where did u bought that bryman tester

[@joesmith-je3tq]

TME

[@claysonwebster1622]

+joe smith OK thanks did u do any review on the bryman

[@joesmith-je3tq]

I ran several tests on it and it frequently is used to compare against other meters but I have never done a review on it. If you watch the videos I made for the UT181A and TPI 194 II, you will have a fair idea how the Brymen stacks up. If there is something specific you would like to see done with the Brymen, let me know.

[@claysonwebster1622]

+joe smith just an accuracy test against a fluke

[@joesmith-je3tq]

My review of the UNI-T UT181A, I compare it with a Fluke 87V, Fluke 289 and the Brymen BM869s. Have a look. kzbin.info/www/bejne/hpuxiZWBoddmg6s