Author Topic: UNI-T UT61E Multimeter teardown photos.  (Read 459394 times)

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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 »
 

alm

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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
 

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.
 

Offline cybergibbons

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #135 on: February 23, 2012, 02:55:37 am »
Normally I'd say it was due to the burden voltage and the DUT changing behaviour as it receives a lower voltage.

The shunt resistor on uA will be quite large, and this means as you approach full range, the voltage drop across it will be large. This will lower the voltage available to the DUT, and will reduce the current. This is especially noticeable on low voltage semiconductor devices where they will just cease to operate and consume little to no current.

However, your readings look odd. For some reason they are higher in one case and lower in another...
 

alm

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #136 on: February 23, 2012, 05:22:49 am »
I think this flashlight contains a DC-DC converter to supply the LED with a constant current, regardless of the cell voltage. By dropping extra voltage over the shunt resistor, the voltage to the DC-DC converter is decreased, so the duty cycle (and therefore current draw) is increased to compensate for the lower voltage. The manual should specify burden voltage (either at max current or in V/A) for the different current ranges.
 

Offline dinoboy

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #137 on: February 24, 2012, 09:03:26 am »
Thanks for your comments. Yes, it is a regulated flashlight for constant light output.

I am thinking, what good is a "89$"-worth DMM if it influences the duty cycle in such a way that i get different readings (almost by factor 2x) in the A vs. the mA range, without a warning? And i am still wondering which reading is correcter than the other..  ::)

Eneloop AAA @1.05V   
0.419A (77.72mA)
0.027A (60.63mA)
oops that was my error. i think that 0.419A are beyond the range of the mA-setting.
 

alm

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #138 on: February 24, 2012, 09:51:36 am »
Yes, the 419mA vs 77mA is strange, maybe the regulator switched to a lower current because it was unable to maintain the higher current? Did you notice a significant difference in light output? See Dave's page about the µCurrent, and the Silicon Chip article linked from that page, for more information about the effect of burden voltage.

Driven from a constant current source (eg. a lab supply in constant current mode), the lowest range including the measured value should be the most accurate, so for values < 400 mA, the 400 mA range should be more accurate than the 10 A range. The 10 A range will have a lower burden voltage, however, so for sources sensitive to voltage changes, especially a regulator that might drop out or shut down if the voltage gets to low, it may be superior. This is where higher resolution and accuracy sometimes comes in handy. This is essentially also what Dave's µCurrent does: use a lower value shunt resistor and amplify the signal to compensate.
 

Offline dinoboy

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #139 on: February 24, 2012, 10:08:45 pm »
Yes, the 419mA vs 77mA is strange, maybe the regulator switched to a lower current because it was unable to maintain the higher current? Did you notice a significant difference in light output? See Dave's page about the µCurrent, and the Silicon Chip article linked from that page, for more information about the effect of burden voltage.
Thanks, will do the reading on burden voltage!

And yes, there was significant difference in light output: When i was in the mA-setting, basically i could not get the light to shine bright in Med-mode anymore. The light's mode sequence is Medium-Low-High, and i was interested in measuring the current in Low-mode. Instead of an DMM error message (Out Of Range) i get low light output when i activate the light (starts in Med-mode), and when i switch to Low-mode the light output is as low.

In fact, the light on Low-mode was dimmer too in the mA-setting compared with the A-setting!

David Jones did the same kind of measurements on his (equally little sized) torch:
h t t p://www.youtube.com/watch?v=0DqHicC6QL4&t=7m15s
« Last Edit: February 24, 2012, 10:23:07 pm by dinoboy »
 

Offline dinoboy

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #140 on: February 28, 2012, 03:03:45 am »
Burden voltage . If you don't know that , that's sad .
Even high end fluke's and vulnerable to aforementioned problem .
okay thanks everybody. i have read the uCurrent article and watched Dave's video. It basically says that my UT61E (and also high-end Flukes) doesnt measure the milicurrent in the "mA/uA"-setting accurately if i dont pay 59.95$ for Dave's product

:D
 

alm

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #141 on: February 28, 2012, 08:08:31 am »
You should look beyond the marketing crap and focus on the technical stuff ;). Not all circuits are as sensitive to changes of voltages. Assume a 7805 linear regulator, which works by dissipating any excess voltage above 5 V. As long as you keep it above 7 V or so at moderate currents, current draw should be almost constant. So a 7805 fed from a 9 V source should have no problem with 1V of burden voltage.

The other extreme is a regulator dropping out of regulation or to a lower current level, like in your example. If you use a variable voltage source as power supply, you can partly compensate for the burden voltage by feeding your circuit a higher voltage.
 

Offline Tangent_Tracker

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #142 on: February 29, 2012, 03:31:47 am »
Today i ordered Uni-T UT71D for 149€ it should come in comming week. IT is from german shop PinSonne Elektronik. After long consideration i decidet for it since price/performance/features it is the best i could find here in EU.
Will you please be good enough to perform a little review of this meter? There is one on youtube but I don't really think it is all that great tbh...
 

Offline cybergibbons

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #143 on: February 29, 2012, 07:08:20 am »
He thought it was crap and returned it, though the specific unit he had obviously had faults.
 

Offline Vredstein

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #144 on: March 02, 2012, 10:32:31 am »
They've changed the layout a bit in the version I got today. Added the C2* component and some other bits.
« Last Edit: March 02, 2012, 10:37:17 am by Vredstein »
 

Offline dinoboy

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #145 on: March 18, 2012, 06:49:30 am »
FYI, the product was reviewed by fellow member HKJ on the flashlight forums:

http://budgetlightforum.com/node/8642
 

Offline LEECH666

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #146 on: May 03, 2012, 08:33:53 am »
Could some of you UT-61E owner tell me if it is normal that the mV (DC) range shows O.L. with nothing attached to the jacks? My DMM does that and I find this kinda weird. The mV (AC) range doesn't do this and reads close to 1.7 mV (once it has settled).

The printing on the Ampere jacks is confusing me too. It says "EACH 15min MAX 10sec" ... ???

So which one is true? 15 minutes or 10 seconds?

Cheers,
Florian
 

Offline Spawn

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #147 on: May 03, 2012, 08:37:03 am »
The printing on the Ampere jacks is confusing me too. It says "EACH 15min MAX 10sec" ... ???

So which one is true? 15 minutes or 10 seconds?

You can measure  the max current allowed only every 15 minutes for 10 seconds long before shunt cools down.

Offline mariush

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #148 on: May 03, 2012, 08:47:08 am »
Could some of you UT-61E owner tell me if it is normal that the mV (DC) range shows O.L. with nothing attached to the jacks? My DMM does that and I find this kinda weird. The mV (AC) range doesn't do this and reads close to 1.7 mV (once it has settled).

The printing on the Ampere jacks is confusing me too. It says "EACH 15min MAX 10sec" ... ???

So which one is true? 15 minutes or 10 seconds?

Cheers,
Florian

Yes, the mV will go to OL with the leads in the air. Tested it right now with my 61E. The mV setting has no autorange so it will go by default to OL.

EACH 15min MAX 10sec   =  perform a measurement for a maximum of 10 seconds, then wait about 15 minutes for the shunt to cool down.
 

Offline LEECH666

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Re: UNI-T UT61E Multimeter teardown photos.
« Reply #149 on: May 03, 2012, 08:57:46 am »
Yes, the mV will go to OL with the leads in the air. Tested it right now with my 61E. The mV setting has no autorange so it will go by default to OL.

Thank you, so my meter is not broken. I'm still wondering why it does that and why it's different for the mV AC range.

EACH 15min MAX 10sec   =  perform a measurement for a maximum of 10 seconds, then wait about 15 minutes for the shunt to cool down.

Thanks for explaining, it probably is also written down in the handbook, but I figured I asked this too since I was about to post the other question anyway.
 


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