Author Topic: UNI-T UT61E Multimeter teardown photos.  (Read 186613 times)

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Offline PedroDaGr8

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #120 on: February 06, 2012, 12:06:02 PM »
As an update, because I was bored. I decided to do some resistance and capacitance measurements. I have some 0.1% metal film (or metal foil they use different names in different places) resistors from KOASpeer. I decided to test their resistance. The ones tested were either 1/3W or 1/4W resistors, though I did have 1/2W 0.1% resistors for 3 of the values. I did a spot check on these 1.2W resistors and they fell exactly in line with the values recoreded for the lower wattage varieties.

33.2K ohm
So actual value can range from 33.17K to 33.23K ohms.
The meters rated accuracy in this range is +/-0.5%. Which is a range of 33.03K to 33.37K
Resistor 1 reading:    33.09K
Resistor 2 reading:    33.09K
Resistor 3 reading:    33.09K
Resistor 4 reading:    33.08K
Resistor 5 reading:    33.09K
Resistor 6 reading:    33.10K
Resistor 7 reading:    33.09K
Resistor 8 reading:    33.08K
Resistor 9 reading:    33.09K
Resistor 10 reading:  33.09K
This gives an average reading of 33.089K which is (assuming the resistors are 33.2K) -0.334%. Which is well within the listed accuracy of the meter. Even assuming the worse case scenario of ALL of the resistor being 33.23K, the error is just -0.434%. The precision of both the meter and the resistors is surpisingly good too.

Next up is a 33.0K resistor.
The resistors would fall within the range of 32.967K to 33.033K
0.5% rated meter accuracy means the resistors should fall within 32.835K to 33.165K
Resistor 1: 32.89K
Resistor 2: 32.90K
Resistor 3: 32.90K
Resistor 4: 32.90K
Resistor 5: 32.90K
Resistor 6: 32.90K
Resistor 7: 32.89K
Resistor 8: 32.89K
This gives an average reading of 32.8975K which is (assuming the resistors are 33.2K) an error of -0.311%. Which is well within the listed accuracy of the meter. Even assuming the worse case scenario of ALL of the resistor being 33.033K, the error is just -0.410%. Once again the precision of the meter AND the resistors is quite good.

Next one is a 2K resistor:
The resistors would fall within the range of 1.998K to 2.002K
0.5% rated meter accuracy means the resistors should fall within 1.990K to 2.010K
Resistor 1 reading:    1.9947K
Resistor 2 reading:    1.9950K
Resistor 3 reading:    1.9948K
Resistor 4 reading:    1.9946K
Resistor 5 reading:    1.9951K
Resistor 6 reading:    1.9949K
Resistor 7 reading:    1.9949K
Resistor 8 reading:    1.9948K
Resistor 9 reading:    1.9946K
Resistor 10 reading:  1.9947K
This gives an average reading of 1.9948K which is (assuming the resistors are 2.0K) an error of -0.2595%. Which is well within the listed accuracy of the meter. Even assuming the worse case scenario of ALL of the resistor being 2.002K, the error is just -0.3591%. Once again the precision of the meter AND the resistors is quite good.

Next up are some 220K resistors. This is interesting because it falls on the edge of two ranges. 220Kohm which has a +/- 0.5% accuracy and 2.2Mohm which has a +/- 0.8% accuracy. I will list the 220Kohm range readings first then the 2.2Mohm range readings for the same resistor in parentheses following.
The resistors would fall within the range of 219.78K to 220.22K
0.5% rated meter accuracy for the 220Kohm  means the resistors should fall within 218.90K to 221.10K
0.8% rated meter accuracy for the 2.2Mohm range means the resistors should fall within 0.21824M to 0.22175M
Resistor 1: 219.67K (0.2192M)
Resistor 2: 219.69K (0.2193M)
Resistor 3: 219.68K (0.2193M)
Resistor 4: 219.68K (0.2193M)
Resistor 5: 219.68K (0.2192M)
Resistor 6: 219.65K (0.2192M)
Resistor 7: 219.67K (0.2192M)
Resistor 8: 219.68K (0.2192M)
Resistor 9: 219.69K (0.2192M)
Resistor 10: 219.68K (0.2192M)
This gives an average reading of 219.68K(0.21923M) which is, assuming the resistors are 220K(0.220M), an error of -0.147%(-0.350%). Which is well within the listed accuracy of the meter. Even assuming the worse case scenario of ALL of the resistor being 220.22K (0.2202M), the error is just -0.247%(-0.4495%). While clearly the 220k range appears to have better accuracy, the 2.2Mohm range still falls within the accuracy listed for the 220K range, which is better than its own.

In summary,  the meter appeared to do better than its rated accuracy which is what you would hope for something fresh from the factory.

Next up its capacitance time. To be honest I am not sure how to handle the errors of the capacitors. Often their listed range is larger than the range of the meter. My guess is just treat them as their nominal value and roll with it. For the sake of honesty I include the worst case scenario value as well.

First up are some Panasonic ECG Stacked Metal Film capacitors. They are rated 100V and 0.1uF +/-5%. The meter is rated at +/-3% in this range. The meter reads in nF in this range so the values should center around 100nF
The values for capacitance could range 0.95uF to 1.05uF
The meter should read 97.00nF to 103.00nF or a .06uF range.
Capacitor 1: 99.20nF
Capacitor 2: 101.17nF
Capacitor 3: 101.22nF
Capacitor 4: 99.27nF
Capacitor 5: 99.99nF
Capacitor 6: 100.36nF
Capacitor 7: 101.68nF
Capacitor 8: 99.28nF
Capacitor 9: 101.06nF
Capacitor 10: 99.66nF
THis gives an average value of 100.289nF which is an error of 0.289% from the expected value. In a worse case scenario where all were 105nF, the error becomes -4.48%. This is still within the error range of the capacitors themselves. So the meter does well.

Next up are some enormous UnitedChemicon 100V 2200uF caps. These things are 50mm long and 20mm wide. So 0.86 inches wide and about 2 inches tall. The meter uses the 2.2 mF (millifarad) range, which is the last one which is makes an accuracy claim for. It claims 4% accuracy.
These like most electrolytics have a +/- 20% rating.
Capacitor 1: 2.1790mF
Capacitor 2: 2.1764mF
Capacitor 3: 2.1758mF
Capacitor 4: 2.1787mF
Capacitor 5: 2.1756mF
THis gives an average value of 2.1771mF which is an error of 1.041% from the expected value. In a worse case scenario of an extreme 2.64mF, the error becomes -17.53%. This is still within the error range of the capacitors themselves. So the meter does well.

Lastly, I have some ESC (or SC) brand crap capacitors rated at 25V 120uF. These are the type of caps you expect to find spewing their guts everywhere in a PSU or in the VRM of a motherboard. I can't find out anything about them but my guess is like other cheap/basic capacitors they are rated at 20%.
Capacitor 1: 126.70uF
Capacitor 2: 127.00uF
Capacitor 3: 125.15uF
Capacitor 4: 128.28uF
Capacitor 5: 126.16uF
Capacitor 6: 127.01uF
Capacitor 7: 127.23uF
Capacitor 8: 129.54uF
Capacitor 9: 126.44uF
This gives an average value of 127.06uF which gives an error of 5.88%. The worst case scenario error is 32.35%. I really believe because of the suspect nature of these caps. The readings are fine, but the error falls with the caps themselves. If you notice they don't have nearly as precise values as the rest of the quality components I have measured. The massive 2200uF cap was consistant into the third digit, where these vary wildly.

So in summary, it seems that the meter is definitely capable of meeting its specified accuracy.
The very existence of flamethrowers proves that some time, somewhere, someone said to themselves, "You know, I want to set those people over there on fire, but I'm just not close enough to get the job done." -George Carlin

Online Aurora

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #121 on: February 06, 2012, 08:33:02 PM »
Nice work  :)

Its good to know that the meter is pretty accurate, in line with its specifications  :)  Where electrolytic capacitors are concerned I have ways considered their actual values to very variable so ballpark with low ESR is good enough for me. Its interesting to see the variance of value in the lower quality capacitors when compared to better parts.

Many thanks for taking the time to do the tests. For a long time I have used some 1% silver mica capacitors and 0.01% precision resistors (Ex 1980's Solartron 19" rack mount multimeter) to test my meters accuracy. They are very old parts now so it is time for me to source some replacements.

Aurora

Offline PedroDaGr8

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #122 on: February 07, 2012, 08:41:39 AM »
Nice work  :)

Its good to know that the meter is pretty accurate, in line with its specifications  :)  Where electrolytic capacitors are concerned I have ways considered their actual values to very variable so ballpark with low ESR is good enough for me. Its interesting to see the variance of value in the lower quality capacitors when compared to better parts.

Many thanks for taking the time to do the tests. For a long time I have used some 1% silver mica capacitors and 0.01% precision resistors (Ex 1980's Solartron 19" rack mount multimeter) to test my meters accuracy. They are very old parts now so it is time for me to source some replacements.

Aurora

0.01% resistors would have been nice. Same with the 1% caps.

I was happy to see the device was well within spec as well. Very happy. All the better for sub-$50
The very existence of flamethrowers proves that some time, somewhere, someone said to themselves, "You know, I want to set those people over there on fire, but I'm just not close enough to get the job done." -George Carlin

Online Aurora

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #123 on: February 07, 2012, 09:36:17 AM »
My 0.01% resistors are pretty old so can't really be trusted now. They read right on my Fluke 87 III though so thats good enough for me  :)

They are HUGE black tubular things encased in black enamel, and mesuring from 15mm to 40mm in length and 10mm to 20mm in diameter ! Very odd looking components, fitted with solder tags and not wire ends. I also salvaged a Weston Cell from the same Solartron meter. The meter was a lab spec unit so had the Weston cell for self calaibration purposes. The cell is still functional but has reached the end of its useful life. You can predict the ageing of the cell in -mV per year quite accurately. My cell has reached the lowest p.d. acceptable for a reliable Weston Cell reference but it is still useful to check high impedance meters for basic accuracy.


Offline PedroDaGr8

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #124 on: February 07, 2012, 03:59:48 PM »
My 0.01% resistors are pretty old so can't really be trusted now. They read right on my Fluke 87 III though so thats good enough for me  :)

They are HUGE black tubular things encased in black enamel, and mesuring from 15mm to 40mm in length and 10mm to 20mm in diameter ! Very odd looking components, fitted with solder tags and not wire ends. I also salvaged a Weston Cell from the same Solartron meter. The meter was a lab spec unit so had the Weston cell for self calaibration purposes. The cell is still functional but has reached the end of its useful life. You can predict the ageing of the cell in -mV per year quite accurately. My cell has reached the lowest p.d. acceptable for a reliable Weston Cell reference but it is still useful to check high impedance meters for basic accuracy.

Yay, mercury cadmium salts. Otherwise known as breakfast. :P Its funny those things are such a good standard but if someone tried bring up that idea today. Everyone would look at them as if they had a third head. You want to put liquid mercury and mercury salts in a cell with what? Cadmium salts too! I should know. I get that look all the time when I talk about making the various cadmium compounds that I make.
The very existence of flamethrowers proves that some time, somewhere, someone said to themselves, "You know, I want to set those people over there on fire, but I'm just not close enough to get the job done." -George Carlin

Offline vk6hdx

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #125 on: February 14, 2012, 03:28:22 PM »
I finally got mine after 6 weeks ago ordering it from DinoDirect.  ::)

All seems good so far, though the box was a little bashed up from the postage.  Build date is 18th November 2011.

Offline dinoboy

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #126 on: February 17, 2012, 05:14:36 AM »
Hello i am new to multimeters and bought this product too from Dinodirect. I am using it for low energy DC circuits such as measuring currents (0.005A to 3.000A) in high power LED handheld flashlights (0.8 - 4.3V operating voltage).
I think the manual is totally lacking. I still dont understand much of the functionality of the multimeter, for example what the "PEAK"-button is good for. If anyone knows a detailed step by step user-guide or tutorial with all sorts of examples, application cases and long explanations and descriptions of all the functions and FAQ's (not the poor documentation manual) for the UT61 series, please let me know.

i have basic knowledge of electronics, that's not the problem. it's the product. it doesnt come with an extensive user-guide which explains the product and its functions in detail as i would have expected. the manual is a joke.

but maybe i shouldnt complain. i paid US$ 30 for it only on Dinodirect with some additional discount coupons.
« Last Edit: February 17, 2012, 05:19:58 AM by dinoboy »

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #127 on: February 17, 2012, 05:48:29 AM »
Try some Fluke or Agilent user guides for multimeters with similar functions. All multimeters are essentially the same once you've figured out which buttons to press. There may also be appnotes out there that tell you how to use certain advanced functions. Some practical electronics books, like practical electronics for inventors, may also explain some of the basics, like measuring current, voltage and resistance.

Don't expect great documentation from vendors like Uni-T. I don't think I've seen one good manual from them. I'm not a big fan of Rigol's documentation, either. This is one area where the more expensive manufacturers like Fluke and Agilent tend to shine. Paying someone to produce good documentation costs money, and this is clearly one area where Uni-T skimps on.

Offline dinoboy

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #128 on: February 17, 2012, 06:09:17 AM »
thanks, will do so. Will also post my other questions in the Beginners section. For our records i found the following picture on the google:


and i dont know how to activate, for example the MAX MIN,
and what the other symbols mean (or when they are supposed to show).

Offline Teknotronix

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #129 on: February 20, 2012, 10:31:35 AM »
Would anyone know why my meter would suddenly start floating the value in the ohms range at about 120-190 MOhms? It's happening with either the leads in or out. I now have 2 of these meters and only one is doing it. Anyone else have this happening on their 61E?
Don't drone me bro!


alm

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #130 on: February 20, 2012, 10:45:59 AM »
Leakage due to contamination, like flux residue on the PCB, which can decrease in resistance after absorbing moisture? This is just a guess.

Offline mariush

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #131 on: February 20, 2012, 11:00:31 AM »
dinoboy, they use the same pcb and lcd screen for the UT-61 A, B,C,D, E multimeters in the series ... the functions are simply not there... for example the EF in triangle stands for electric field testing (when the meter detects wire in the walls or current in the wall sockets etc) and there's no sensor/antenna inside the meter for that, but the 61A has it.

See the manual, page 11 and 12: http://www.uni-trend.com/manual2/UT61English.pdf

EF is in 61A
the icon in the corner is sleep mode (again 61A and maybe others)
MAX / MIN is in several models (a,b,c,d) 
etc

Offline Teknotronix

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #132 on: February 20, 2012, 04:05:05 PM »
Leakage due to contamination, like flux residue on the PCB, which can decrease in resistance after absorbing moisture? This is just a guess.

Bingo! Cleaned up a few parts of the PCB with circuit board cleaner and she is working fine now. Thanks :D
Don't drone me bro!


Offline T4P

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #133 on: February 22, 2012, 06:14:56 AM »
Nice meter ! placing an order soon  ;D
http://the4thpin.comeze.com <-- Rants and Reviews! sorry my english  :palm:

Offline dinoboy

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #134 on: February 23, 2012, 02:35:32 AM »
thanks.
while i still dont understand/know all the buttons of the meter and how to employ them favourably (guide, strategy, examples, application, anti-examples) i have a more urgent question:

Why do i get really different readings for current when i switch from "A" to "mA/microA" (in parentheses)?

For example:
Eneloop AAA @1.47V   
0.130A (155.13mA)
0.015A (24.37mA)

Eneloop AAA @1.05V   
0.419A (77.72mA)
0.027A (60.63mA)

Varta NiMH @1.47V   
0.136A (146.35mA)
0.015A (24.29mA)

I could tell by visual inspection that the voltage drop in the 61E must be higher when i switch to the "mA/microA"-setting, because the original resistor in the circuit consumes much less energy (Watts), which means that the values in parentheses must be less accurate (i guess?). Basically i am measuring currents in a flashlight:
http://www.lygte-info.dk/info/Measurement%20UK.html

i am confused.


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