EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: Wytnucls on March 06, 2013, 08:17:26 am
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1.Presentation:
The LCR meter comes in a professional-looking strong plastic box with a built in carry handle and internal protective foam cut-outs. It offers some really good protection and stores all accessories: Tweezers, USB cable, jack adaptor, battery, Simplified Chinese manual, sotfware CD, the shorting plate and the warranty card. This one was made in December 2012.
2.Ergonomics:
It feels a bit light for a bulky-looking, squarish meter (374gr), compared to the thick skinned CEM with its heavy 6 AA batteries, for example.
It has a skinny plastic bail holding the meter at a precarious 60 degree angle from vertical, but has a locking mechanism for the bail in both open and closed positions. The bail is very similar to the one fitted to the UT-61E.
The square bodywork could have been made a bit more curvy, to make it more comfortable to hold in the hand, like the 61E.
The LCD is well protected, with an extra window, which forms part of the enclosure. It comes with solid state switches with rubber push buttons, which unfortunately sound a bit hollow when pushed.
There is a perimeter ledge around the power and function buttons which makes them uncomfortable to the touch, but helps to prevent unwanted activation, if something happens to be lying flat on those buttons. A feature the CEM meter sorely lacks.
The most used buttons (Power and Function) really stand-out, being made of a bright yellow and blue rubber, with the colour black used for the lesser remaining buttons.
There is a slight rattle from the folded bail, when the meter is moved around on the bench. There are no rubber pads underneath, so the meter tends to slide around too easily, when lying flat on the bench.
A self-tapping screw for the battery compartment hides a flimsy soft 9 volt battery connector.
3 self tapping screws and 2 clips on top of the unit are holding both tight-fitting clamshell body together. It is an adequate construction, but could have been made more rigid. It also sounds a bit hollow when tapped, because of the thin rubberized plastic walls and large internal volume.
Unlike the Mastech, which is using the same chipset, it has a dedicated calibration button on the front face. I cannot understand Mastech's thinking actually, because I use that calibration button all the time. They go and hide it away in the most awkward position.
There are 3 buttons with dual functions, reducing the need for a confusing multitude of pushbuttons, like those found on the IET machine.
The jacks are good and sturdy, made of one piece metal tubing, with connectors screwed on internally.
The mini USB connector is located at the top of the unit, with APO (auto power off) override, when USB is powering the meter.
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3.Functions:
The meter comes with a 9V battery, but can also be powered independently through the 5V USB connection. It will keep working, even if the 9V battery is removed.
The USB datalogging stream is sent to the computer through the same USB connector. The meter comes with a CD containing the dedicated software and some user notes in English.
There is an auto detection of components, which is the standard configuration at power-up, with a manual selection also possible, through a toggle switch, labelled 'FUNC".
The standard 1 kHz frequency can be modified at any time and the secondary parameter can also be changed, when in manual mode.
Automatic serial/parallel mode selection is done according to device under test, with manual override possible in manual mode.
Other functions are:
'Sorting' mode, (manual selection of % deviation) with a Pass or Fail message. (0.25%, 0.5%, 1%, 2%, 5%, 10%, 20% and +80%~-20%)
Sorting is only available in manual mode with an ideal DUT connected to the meter. Pressing 'SET UP' will allow you to change the range of the ideal reference device, using the lateral arrow keys. Pressing 'ENTER' will now allow you to change the value of the reference DUT, using all arrow keys. Another press of 'ENTER' will bring you into the tolerance selection.
'Calibration' mode, to null the test leads or tweezers with shielding and guard connection.
Press 'CAL' to access 'Open' mode, with an open circuit (loose test leads), then 'CAL' again to enter a countdown to 30s. 'PASS' or 'FAIL' should appear on screen. Press 'CAL' again, if the first test was successful, to enter the 'Short' mode, with a closed circuit (shorting bar or test leads connected together) then 'CAL' again for a 30s countdown with 'PASS' or 'FAIL' message. Press 'CAL' again to exit this mode.
Calibration should be done each time accurate measurements are required or if different test leads are connected.
'Relative' mode to display a deviation as a %, from a reference DUT. It is only available in manual mode. Pressing 'REL' to access the feature, brings up a triangular icon on screen. Connecting another similar device, will display a difference in value as a percentage of the initial measurement. Pressing 'REL' again will display the initial value with a flashing triangle (delta) as a warning. A long press of 'REL' will exit this mode.
'USB' mode, to send a data stream to logging computer. The data consists of primary value, mode and unit, secondary value, mode and unit and the testing frequency. A computer icon appears in the screen. APO goes off, as soon as the USB cable provides 5V to the meter. The Baud rate is 9600.
4.Usage:
The LCD is easy to read, but is best seen from a slight angle (10 to 20 degrees from vertical), just like the CEM DT-9935. All the UT612 meters seem to behave the same way, so it was either designed like that or UNI-T and CEM bought a whole batch of faulty LCDs a few years ago. :o
It isn't really an issue, once you're aware of the unusual behaviour.
The backlight is fairly strong and evenly spread and will last for 60 seconds after activation.
The LCD has a bargraph, marked as a percentage of full range (20,000 count). For example, a 100 ohm resistor will register as 50%.
There is a reduced count of easy access buttons, compared to other meters, making it easy to make the right selections in a minimum of time.
Convenient use of USB for both logging and external power ( works great, unlike the Mastech external power unit)
It comes in a fairly small size (224mmx172mmx59mm), just a little bit bigger than the UT61E. No unnecessary bulk, like on the Mastech behemoth.
It is light, with a single 9V battery.
It comes with a great hard protective storage case, like the IET 5000 meter, which is quite unusual at that price point.
It has 10 reliable solid state buttons instead of a multitude of soft PCB contact buttons like on most other meters (14 on the CEM LCR meter).
One has no control over the APO (Auto Power Off). It is always active with the battery, but goes off when powered through USB. After 3 beeps, the meter will auto shutdown after about 6 minutes of inactivity, when powered by the battery.
The piezo beeper can be heard loud and clear, unlike the one in the CEM meter, which is rather quiet.
The SMD tweezers come with an extra shield lead for connection to one of the guard jacks.
Low battery warning and shutdown is triggered at 5.5V.
Available frequencies are: 100Hz, 120Hz, 1KHz, 10KHz and 100KHz.
The measured secondary parameters are Q, D, ESR, Rp and Theta.
The shielding test lead connection to Guard should be used while measuring resistances above 10M Ohms, to minimize noise and parasitic effects.
Large caps should be measured in series at 120Hz, small ones in parallel, at 1 KHZ, if less than 0.01 uF. Large filter inductors above 200H, should be measured at 120Hz, small audio/RF inductors at 1 or 10 KHz, if less than 2 mH.
5.Limitations:
20,000 count on primary display, 2,000 count on secondary.
No voltage can be applied to the jacks.
There is no input protection.
4 wire measurement is possible (removing PCB trace resistance only, not contact point resistance) with the special jack adapter, but doesn't work with Kelvin testing leads.
No DC bias can be applied to the jacks.
The meter impedance is 120 Ohms and the test current is 4.5mA~5mA RMS.
6.Construction:
The 2 halves of the meter can be easily separated, by disconnecting the joining wires, if required. The USB PCB is held in place by one screw and the battery wires and battery connector can be threaded through, once a little trap door with clips is removed. There is no shielding in the bottom piece, just like all the meters using this chipset.
4 self-tapping screws are holding the main PCB in place.
Don't undo the topmost screws which secure the backlit LCD to the PCB, unless you have to. 2 LEDs are installed for backlighting through a large diffuser. The whole LCD/diffuser/Zebra connectors/LEDs contraption is difficult to put back together correctly, even after careful dismantling.
It is a double-sided PCB, with a limited number of components, as the chipset does most of the work:
U1 Cyrustek ES51919Q
U2 Cyrustek ES51920A (Not the S model, like the CEM or Mastech)
U3 24C02H Serial I2C EEPROM 2KB
U4 TI 430G2202 2KB flash 256B RAM 20-TSSOP uController
U5 3.5V voltage regulator
U6 5.0V voltage regulator
U7 TI AEH7M Multiplexer/De-multiplexer
U8 TI AEH7M Multiplexer/De-multiplexer
1 VR trimpot (probably Ohm adjustment)
2 crystal oscillators (3.999/24.000)
There is also a small separate PCB for the USB connector in the bottom shell. 3 unsightly wires provide USB data link and power connection. The wires are soldered directly to the PCB, instead of connectors, then covered with sealant to provide some stress relief.
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7.Software:
There is a convenient dedicated USB push-button to activate the PC connection.
Just install the UNI-T software that came on the included CD (unlike the IET) and no special drivers are required. The software will look familiar to the owners of UNI-T 61E and 71B/C/D/E. Be aware that I found an incompatibility with my USB Logitech MX mouse, so I have to disconnect it while using the logging software, otherwise the meter is not seen by the PC.
The program is a bit cumbersome at first, with its 1 second interval constant logging, but becomes quite useful after some taming.
I found that the best way to log samples, is to measure the first one, then log the data with the software connection button on the top left of the window, then immediately turn it off, after it appears in the list. Then repeat the procedure for each component. Leave the 'Repeat' and 'Sample interval' unselected. The Graphing software is unwieldy, with its auto vertical axis scaling based on measured value and full range, with no option of zooming on the pertinent area. A picture of the graph can be saved as a bitmap though.
The samples are logged as value (with a maximum of 60,000 apparently), current mode and units with the secondary parameter data and a date/time stamp included. It is much better than the Mastech software, which doesn't log much of anything.
The list can then be saved to an Excel spreadsheet with all parameters.
The Pass/Fail logging is also possible as seen on the picture below.
8.Overall value:
Fantastic price for such a full functionality, with no additional costs for USB logging, unlike the IET 5000.
I paid 115$ in China with tax included (17%). It costs slightly more on eBay.
Great convenience with USB power and logging at the same time. It doesn't even need costly batteries, it can run from USB power alone.
Auto APO selection depending on whether the machine is powered by battery or USB.
Fast accurate measurements. (Twice as fast as the CEM meter)
There is a Hold feature to freeze the display.
In China, the meter comes with a 1 year warranty.
The testing voltage is only 0.6V, allowing in circuit testing.
Overall, a well built LCR meter for the price-conscious hobbyist. Possibly not the most accurate LCR meter out there, but very useful nonetheless.
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Great review & tear down, thank you ! :-+
0.6 V in circuit testing
If this is not troubling you too much, please do a measurement with a scope at the measuring signal, say like at cap with low esr and high esr, really curious to see if it maintains the strict low voltage signal across different DUTs.
Interesting piece of gear, looking at it's price, have to agree this is quite a bang for the buck.
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Here you go:
As expected, voltage
without DUT 0.613V RMS
with 47.0 Ohm resistor 0.159V RMS
with 0.24 Ohm ESR cap 0.014V RMS
The meter impedance is 120 Ohms and the test current is 4.5mA~5mA RMS.
I have also uploaded here the Cyrustek LCR bridge ES51919/ES51920 chipset information and the datasheet for the multiplexers.
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Here are the resolutions and accuracies on all ranges, copied from the UNI-T booklet:
(The capacitance page has a sticker to correct the stated 2%+5 accuracy of the 1 KHz 2000uF range)
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Thanks for your review, it seems very reasonably priced for what you get. I don't see how you could do four-wire measurement with the adapter when the jacks are only two-wire with guarding.
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You get 4 wires to the jacks, eliminating the resistance of the traces, with little resistance remaining afterwards, through direct contact of the DUT with the adapter and the jacks. Not fully 4 wires like with Kelvin clips, but pretty close.
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Very nice review Wytnucls :-+ For the price it seems very good. If you could make or source the split banana jacks that are in the DE-5000 you could replace the jacks and carry the 4 wire measurement out to split banana attachments. I have not compared the specs but this at first glance looks better than the Mastech.
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That sounds like open-heart surgery, but I'm sure somebody will give it a go, now that you mentioned it! :D
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Here you go:
As expected, voltage
without DUT 0.613V RMS
with 47.0 Ohm resistor 0.159V RMS
with 0.24 Ohm ESR cap 0.014V RMS
I have also uploaded here the Cyrustek LCR bridge ES51919/ES51920 chipset information and the datasheet for the multiplexers.
Thanks a lot.
vPP only at 0.47 :-+
(https://www.eevblog.com/forum/testgear/review-and-tear-down-of-uni-t-ut612-lcr-meter/?action=dlattach;attach=40699;image)
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That sounds like open-heart surgery, but I'm sure somebody will give it a go, now that you mentioned it! :D
good review and photos. I don't think it would be anywhere near as hard as surgery. The only hang-up might be the dimensions of the replacement jack sockets, as most people would still want to retain the same case. The one advantage of the mastech and any meter with the slot style sockets is that it is practical to make your own kelvin adapters from double sided copper-clad pcb material. You don't even need to plate the copper, it is fairly easy to burnish and clean the contact patches each time you want to switch adapters.
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Do you have any issue with the viewing angle of your UT612? I bought one a while ago but the LCD is terrible. I can barely see anything if I look directly at it. It has to be viewed from like a 30 or 45 degree angle to see things clearer.
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Do you have any issue with the viewing angle of your UT612? I bought one a while ago but the LCD is terrible. I can barely see anything if I look directly at it. It has to be viewed from like a 30 or 45 degree angle to see things clearer.
From above photos, it doesn't look to have this problem, photoshoots of your lcd from various angles please.
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From above photos, it doesn't look to have this problem, photoshoots of your lcd from various angles please.
I tried, but somehow it always looks better on photos. In real life the display is really pathetic.
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Perhaps video?
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Do you have any issue with the viewing angle of your UT612? I bought one a while ago but the LCD is terrible. I can barely see anything if I look directly at it. It has to be viewed from like a 30 or 45 degree angle to see things clearer.
Hi Franki,
Yes, I mention it in the review somewhere. Mine is possibly not as bad as yours. The CEM DT-9935 LCR meter has the same quirk. I actually took my CEM back to the shop for a replacement, but the new one was just the same. So, I now call it a feature. 8)
Looking at it straight on, the digits are slightly fuzzy and dimmer. The screen becomes sharp, from about 10-20 degrees from the vertical. It's not really an issue, once you get used to it. Especially, if one uses the meter lying flat on the bench.
The backlight makes the effect a little worse.
I'll try to shoot a video to capture the strange behaviour.
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Thank you for the review. Unfortunately, this UT612 is IMHO not better than my DT-9935... It has the same disadvantages. No 4-wire measurement and no input protection. It must have a slightly different chipset, if it works faster... In Czech republic you can buy the dt-9935 quite cheap for 75 € (Euro). http://www.gme.cz/digitalni-multimetry-s-funkci-rlc/multifunkcni-rlc-metr-cem-dt-9935-p722-436/ (http://www.gme.cz/digitalni-multimetry-s-funkci-rlc/multifunkcni-rlc-metr-cem-dt-9935-p722-436/) The UT612 is always much more expensive, at least in Czech Republic.
If I wanted a better quality LCR meter, I would buy the Mastech MS5308. It has AFAIK better true 4-wire probes.
https://www.eevblog.com/forum/testgear/mastech-ms5308-lcr-meter-with-esr-measurement-on-discount-at-the-moment/ (https://www.eevblog.com/forum/testgear/mastech-ms5308-lcr-meter-with-esr-measurement-on-discount-at-the-moment/)
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None of the LCR meters based on the Cyrustek chipset have input protection, not even the IET 5000. Some, like the CEM can handle a maximum of 30 volts on the input jacks.
The UNI-T has a small advantage over the CEM for measurement, providing 4 wires to the input jacks.
If you need genuine 4 wire measurement with Kelvin clips, indeed rather buy the Mastech or the IET 5000.
The main advantage of the UNI-T meter is the convenience of the mini-USB connection for power and communication. The CEM doesn't have external power or datalogging.
I haven't seen the IET logging software yet, but the UNI-T has a more advanced logging program than the Mastech.
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Well, the DT-9935 also has four jacks, but it is not much useful. The absence of external power supply is a big disadvantage...
Anyway, I don't know how many people actually need the datalogger via USB feature.
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I didn't say 4 jacks, but 4 wires or 4 traces on the PCB going to the 2 input jacks, not the guard jacks. The CEM only uses 2 traces.
After proper calibration, there would be extremely little difference between measurements with Kelvin clips and the UNI-T adapter.
I think you have a wrong conception of what Kelvin clips are for. There are really useful to measure small resistance at a distance, which do require long leads to the DUT. In other circumstances, with very short electric paths to the DUT and proper meter calibration, measurements would be essentially the same. I don't know how many people actually need the Kelvin clips feature.
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The long leads you can compensate for, their resistance is constant. Kelvin connections are critical once contact resistance between the probe/clip and DUT becomes significant. This contact resistance often varies between measurements, and may be dependent on force. Kelvin connections can compensate for this variation.
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Thanks for the review Wytnucls, this one is looking really nice with its case and all. The one I reviewed was low end for sure, this reminds me the difference in the insulation testers I got, UT501 and UT511.
If you want quality with Uni-T you have to pay more for it, but the price is still good on the market compared to other equipment makers.
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I didn't say 4 jacks, but 4 wires or 4 traces on the PCB going to the 2 input jacks, not the guard jacks.
Wytnucls, assuming I don't mind voiding warranty by doing some minor surgery and do some mod at the connectors, is it possible to have 4 wires Kelvin clip ? I can't see clearly at the board detail at the input section from your board photo.
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Here is a better PCB picture, with a close-up of the jacks. At first glance, it seems possible to modify for a proper 4-wire measurement system. You would need to investigate further, before you start hacking at your meter.
I think you would be better off buying an LCR meter with the 4-wire function out of the box, if you desperately need that feature. I personally think Kelvin clips are a bit overrated on a low resolution machine like this and I bet you won't see any dramatic increase in accuracy, after your modification.
Nevertheless, it might be easier to use the 'Guard' jacks for the 2 additional 4-wire connections, as a guard connection is only useful if you measure a resistance above 10 MOhms anyway. If you want to keep a 'Guard' connection, it would be relatively easy to install a fifth jack with a PCB plane connection for that purpose.
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Wytnucls, thanks for the close up shot.
Yeah, don't think that kind of modding is necessary, but as a tinkerer this is an option for the future just in case if needed. ;)
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The long leads you can compensate for, their resistance is constant. Kelvin connections are critical once contact resistance between the probe/clip and DUT becomes significant. This contact resistance often varies between measurements, and may be dependent on force. Kelvin connections can compensate for this variation.
Quite correct Alm. So, it is very important to have a good electrical connection to the DUT with a 2-wire system to measure small resistors of less than 1 Ohm. Whether the 2 connecting pressure plates on the UNI-T adapter are sufficiently adequate, I don't really know. Contact resistance is usually about 1mOhm.
I did run a test with a 30cm length of wire on the UT612, with the ends pushed through the blade connectors after calibration, which gives me repeatable measurements of 5milliOhms in Rs 1KHz mode. I don't have the instrument to measure the actual resistance of that wire, unfortunately.
Here is a sample of small 10% inductors measurements taken both with the UNI-T and the CEM 9935, using the pressure plates and also a sample of 1% resistors using a 1KHz frequency and short leads and clips (resistor legs are too thin to push through the plates), with the UT71D DMM as an extra reference:
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Here is a better PCB picture, with a close-up of the jacks. At first glance, it seems possible to modify for a proper 4-wire measurement system. You would need to investigate further, before you start hacking at your meter.
There is no doubt that UT612's PCB is better designed than DT-9935.
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Here is a selection of small caps measured with both LCR meters again, using short test leads and clips and also some electrolytics:
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Some inductor measurements, with short test leads and clips:
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Thank you very much for the awesome review.
You created the spreadsheets the same way I would have, with all of the parameters/data desired.
The photos are also very useful; they are taken in a way that I can grasp the real-life size of the parts.
After reading your review, I made one click on eBay without a second thought, and purchased one for $153 including shipping to California.
Regards.
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Thank you for the kind words. I sure hope you won't be disappointed.
Unfortunately, I don't own shares of the company (UNI-T is a privately-held company, with the owner based in Hong Kong). Let us know later if the meter lived up to your expectations.
If enough people are interested, PM Franki first, as he can probably beat that price with direct sales to members of this site.
http://stores.ebay.com/99centhobbies (http://stores.ebay.com/99centhobbies)
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I had a look at the IET logging software. It is more sophisticated than the UNI-T program, with mostly better control of the graph display scales and a proper manual trigger control on key F12.
It is freely available on the IET site, if anybody wants to have a trial run. And, no, it is not compatible with the UT612. :)
Of course, it comes at extra cost, as it needs the dedicated USB LCR meter hardware interface connector to work properly.
Incidentally, IET doesn't give you proper 4-wire Kelvin clips with their meter either. You will have to buy those separately or modify the standard crocodile ones. SMD tweezers are also available, but I don't think they are proper 4-wire Kelvin to the tip, only to the handle.
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Just install the UNI-T software that came on the included CD (unlike the IET)
My IET came with manual and a CD with software, but I have bought it including the USB interface, tweezers and psu.
The IET had several connectors. The blade connectors are true 4 wire. the adapter you can push in there forthectweezer or croc leads are using that 4 wire connection. The adapterd uses 4 guarded wires ( technical speaking the IET is 5 wire) to go to the croks, but the croks are not 4 wire ( they are however one best made croks I have ever seen) the tweezers are 4 wire upto the start of the tips, so the last cm or so is not 4 wire but that is more then good enough. The guarding is more important in my opinion as that last cm ( doing L and C measurements)
I found one strange thing in the IET, the banana jaks are true 4 wire jacks, so you could use 4 wire if you had special bananas ( that AFAIK do not excist) but in that case the blade connectors make still contact and so cancel your 4 wire connection. The strange thing is non of my bananas fit, the holes are just smaller in diameter. So they made special 4 wire bananas that can not be used for 4 wire technic because there are no bananas that fit and if there were bananas, the blade connctors would short out the 4 wire connection.
I just made a small alu box with 4 banana jack, 4 bnc sockets and a lemo connector and a guard connector. All parallel so can be used as in or output. I have two hirshman probes that could be opened. I made 5 connctions using 2 lemo multiconductor wires from a lemo plug to both probes. Only the last 2 cm is one wire. I used these because they are low thermal and the tips are a mix of bananajack and probetip. So multifunction.
I have good kelvinclips but not ith guarded wires. I will replace the wires with 4 x RG 179 and bnc so it will be true 5 wire.
The banana jack will be used to connect to a 4 wire multimeter, and i make a cable that goes from a bridge 3 wire system to the IET 5 wire system.
To connect it to the IET i am still in doubt. I think I make a small adapter using pcb like the original adapters and the 4 guarded wires to the lemo socket or to the bananas. Or ad a lemo socket to the IET adpter and mount the existing crock wires to a lemo plug. Then I can use a lemo-lemo cable to connect the adapter to my 4 bnc adpter. I must do some tests what gives best results.
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Thanks for that information about the IET LCR meter, PA4TIM. It seems that IET didn't take that 4-wire measurement very seriously either.
As Alm pointed out, a major benefit of the 4-wire system is to cancel out most of the errors generated by contact resistance between DUT and test gear. So croc pincers or tweezers with only 2 contact points don't really qualify as precise 4-wire systems.
At least, with the DE 5000, you have the option to improve on the standard IET gear, by making your own Kelvin clips or tweezers, using the 4-wire blade connections.
As far as I understand, the guard connection is only necessary for resistance measurements above 10 MOhms and may have little effect, if any, on L and C measurements.
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The IET makes a very good job out of the 5 wire technic. Only strange the bananas are added. You can easy exand the 5 wire conection by altering the crocs adapter. That s what I probably will do. For a DC uOhm meter the adapers like they are now, would not be the way to go. But this is a LCR meter.
The resistance added by the crocks themselve or the last cm of the tweezers is neglectable if you consider the accuraty and resolution. I did buy this for LC measurements. ESR is a non accurate parameter ( it is instable, every measurement will differ more as the R residu from the adapters)
And for mOhm I use my GR1608, Boonton or 7,5 digit multimeters. For high Resistance measurement
Guarding has an advantage too, but then shielding is often enough. I have a POhm meter that uses a guard driven sense input,
I made a 4 wire adapter yesterday that uses 4 bnc and optionl guard to connect to lcr meters, bridges and multimeters. Also made rg179 wires to my kelvin clips and rebuild two hirshman probes. The difference between the two is 4-8 mOhm. Easy to zero out and in most modes in the error zone ( seebeck, EMC, accuracy error, ect)
More important is the fact they use 4 wires to go to the crocs and tweezers and use a guard signal for the shield. The shield is called the 5th wire. This is important for capacitance meaurement because it minimises capacitance between the wires. By driving the shield with a guard signal there is no voltage difference between the sense line nd shield, hence no capacitance. Ths technique was common on lab grade bridges. They most times use 3 wire because reistance is not as important there. ( ESR measuring pF or aF is in the order of kOhms, so a few mOhm in the wire is noproblem, but upto 100 pF is. The guard driveh coax minimises this stray to under 1 pF after 1 meter of coax. On my GR1620 in a guarded farraday cup it s in the fF region.
GR has a few experimenters written about guarding ad multiwire Measurements.
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At least, with this meter, you have the option to improve on the standard IET gear, by making your own Kelvin clips or tweezers, using the 4-wire blade connections.
Ahh.... finally, actually I've been waiting and expecting to hear these words straight from you. ;D
Btw, thanks again for those extra measurement results with pics, well done and really like the presentation ! :-+
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More important is the fact they use 4 wires to go to the crocs and tweezers and use a guard signal for the shield. The shield is called the 5th wire. This is important for capacitance meaurement because it minimises capacitance between the wires. By driving the shield with a guard signal there is no voltage difference between the sense line nd shield, hence no capacitance. Ths technique was common on lab grade bridges. They most times use 3 wire because reistance is not as important there. ( ESR measuring pF or aF is in the order of kOhms, so a few mOhm in the wire is noproblem, but upto 100 pF is. The guard driveh coax minimises this stray to under 1 pF after 1 meter of coax. On my GR1620 in a guarded farraday cup it s in the fF region.
I hesitate to differ with you on any topic but aren't you confusing a guard connection and a driven shield? The guard is the circuit common of a simple auto ballancing bridge. (Covered very nicely in the Agilent impedance handbook starting in section 2-14) I think the DE-5000 is only a simple guard.
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There is much confusion about guarding because the term is used not very uniform. Not only between brands but also between models from brands themselve.
The configuration is also not obvious. The main function is to shield a sensitive input from "something"
In case of the PetaOhm meter it is a driven guard to make sure the current does not leak over the shield. If there is no potential difference there will flow no current. My Tek 130 LC meter also as a driven guard. But here to minimise stray capacitance.
Some meters have active guards and separate ground connections, but with an optional shorting bar between them. Like the Fluke 845 , 8500 and my HP sourcemeter.
It can be a passive form, i have an electrometer that has a sort of grounded guard grid between inputs and the rest. The HP 4260 also uses this. This adds capacitance,(no problem for DC) between traces to decouple, but also sometimes to make sure no current leaks from the source or higher voltage traces to the input.
I have a Fluke DC standard with a guard connector ( printed on the cabinet) and that is just connected to ground, seperated from the low terminal by a capacitor, so this is a passive ground. An other Fluke calibrator has a guard, sense, and gnd ( 6 terminal connection) the ground is the cabinet, so fluke uses guard for two different things and both instruments are from the same line/area. I also have seen a resistor between low and guard, or low and ground.
In a capacitance meter you see passive and active guards ( guarding is in fact protecting, shielding is protecting too, so that makes it difficult to see what they mean by it.). Sometimes it is not a closed loop, so the shield is connected at one end only, sometimes it is closed ( for instance when shielding for EMC or RF ( to keep signal from entering or the otherway around, preventing radiation) . It depends on the construction. You want an as less possible stray capacitance between souce and sense. If the sence impedance and signal is very low, a passive shield can sometimes be enough. This is very nice explained in several GR experimenters ( downloadable at IET website) but sometimes it needs to be driven. It is not allways very clear what they do. For instance in the GR1620 there are 3 ways to measure and two of those are 3 terminal. One uses two shielded GR connectors, this gives allmost no strays, the other is using three banana terminals, the third is using 2 of those bananas. You need to switch to those modes. The GR1608 and 1650 use two or three wire mode but you do not have to siwitch between modes.
I made some guarded circuits, sometimes passive by using a high Ohm resistor to couple the measured signal to the shield. No current flow, just an electric field to make potentials equial. But I used driven guard to by using an opamp to drive the shield. And things like traces, sometimes grounded, somtimes driven by a resistor or opamp.
The IET can be passive, or active, i have mot measured, but it does makes a difference in result.
Most important thing is that a manufacturer uses the way that fits the design and optimizes performance and I think it is save to say that if IET choses a way they do it for the right reason because they do know how to build good LCR meters. I think IET(GR), ESI and Wayne Kerr are the brands with the most experience in builing LCR meters, bridges and standards.
Just some things i collected about guarding, upto now i have not find a uniform explanation. Every brand seems to have its own definition about guarding. The Keithly book also talks about guarding.
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The guard connection appears to be the same configuration on all four meters (DE-5000, Mastech MS5308, CEM DT-9935 and UNI-T UT612): A simple direct connection to the PCB ground plane.
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Thanks for looking, i do not want to open my meter ( i know, the motto is " take it apart" ;-) but that is not my motto unless it needs repair) so it looks like it is a passive guard. But in my opinion, it does not matter what kind it is, as long as it works and it must be accesible for the user. I often use farraday cups but also standards that have guard connections and then you need acces to the connection.
This is the kit I made. The lemo is for the normal probes but also to make a shieded connection to the IET. But I'm still thinking how I'm gonna do that. First I think I wil make a kelvin adapter by turning two connectors on my lath, split them and separate them by teflon make a bridge to hold them in position ( so make a connector like the double pomonas) and then to the lemo connecor. Or I maybe replace the existing croc wires with two longer ones and a lemo connector.
(http://www.pa4tim.nl/wp-content/uploads/2013/03/Kelvinprobeset.jpg)
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Thanks for the Review, was thinking about getting one and after the review I'm going for one.
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Hi Wytnucls,
I got the UT612 mainly for measuring caps, I'm very new to electronics so I need some help please.
What are the typical values for ESR for a cap to be considered good:
Should I use this table from the old Bob Parker ESR Meter:
http://i1119.photobucket.com/albums/k636/mib_instruments/mib_instruments2/PreP1070439.jpg (http://i1119.photobucket.com/albums/k636/mib_instruments/mib_instruments2/PreP1070439.jpg)
Or should I use this table from peak atlas ESR meter:
http://dc338.4shared.com/img/kwg9wwYx/s3/esr_meter_table.jpeg (http://dc338.4shared.com/img/kwg9wwYx/s3/esr_meter_table.jpeg)
Or this chart from the Blue ESR Meter:
http://www.electronicrepairguide.com/images/blueesrmetertestchart.jpg (http://www.electronicrepairguide.com/images/blueesrmetertestchart.jpg)
I also got these cables:
http://i.imgur.com/TZZxKJ2.jpg (http://i.imgur.com/TZZxKJ2.jpg)
But the meter does not pass the calibration, are the cables too long? Any suggestions?
Thanks.
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Hi,
I'm no expert on electrolytic caps, but I think that the best procedure would be to work from the datasheet, if you can find one.
Most datasheets for electrolytics will give you specs based on Tan d (D).
I would first measure capacitance at 120Hz, to find out if the cap is still within the usual 20% limit of the published rating and then compare Tan d (D) with the original max figure, to see if the ESR has increased dramatically. Tan d should be no more than 150% of the max published value.
If both capacitance and tan d are found to be out of limits, the cap is probably bad.
If you can't find datasheets, those tables should help you, if you prefer to work with ESR figures. Be aware that low ESR electrolytic caps, found mostly in power supplies, will have different parameters.
Kelvin tweezers or pincers are nice, but won't give you better measurements, as this meter is not a 4-wire instrument. To pass calibration, the test leads should be shielded and equipped with a guard connection or, if not shielded, kept as short as possible. I would recommend short test leads with small croc connectors.
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Thank you for the response.
I have an assortment of caps from different manufactures and even of different series, it would take a long time to hunt every specific cap datasheet and all I need are ballpark numbers.
I don't think the leads are shielded. Will try to shorten them and see if they pass calibration.
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If you are obliged to work with ESR ballpark figures, that can be done with the dissipation factor (D) too. The advantage being that it is mostly independent of capacitance. The only variable is the capacitor rated voltage.
Here is a table listing dissipation factors for different caps from several manufacturers. You will notice that the values are not very different, even between series.
Any gross deviation from those figures for a cap under test would mean a necessary replacement.
For known Low ESR caps, any measured dissipation factor above 0.10 should be treated with suspicion.
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Wytnucls (or anyone with this meter),
I know the maximum cap value is 20,000uF but will it measure ESR (or dissipation) for a cap greater than this?
Thanks
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Wytnucls (or anyone with this meter),
I know the maximum cap value is 20,000uF but will it measure ESR (or dissipation) for a cap greater than this?
Thanks
Use Rs mode to measure the capacitor. Rs mode is equivalent to ESR measurement.
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Wytnucls (or anyone with this meter),
I know the maximum cap value is 20,000uF but will it measure ESR (or dissipation) for a cap greater than this?
Thanks
Use Rs mode to measure the capacitor. Rs mode is equivalent to ESR measurement.
Much appreciated. Still shopping and looking for any weaknesses for my uses. The other question i have is... does the lack of true kelvin probes compromise much on this meter?
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Much appreciated. Still shopping and looking for any weaknesses for my uses. The other question i have is... does the lack of true kelvin probes compromise much on this meter?
One other major issue of the UT612 (seems worst on my unit than Wytnucls') is the LCD display. It's almost completely washed out if I look at it from a direct angle. I have to look at it at a 45 degree angle.
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Is this not true on other meters like the CEM? IIRC, it had the same issue.
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Is this not true on other meters like the CEM? IIRC, it had the same issue.
I have not tried the CEM so can't comment on that. But the Mastech MS5308 definitely doesn't have that problem. It has a super big and clear LCD display.
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Has the PSU issue on the Mastech been sorted yet? I can find the Mastech for about $180 so I may go for that instead since its true 4w.
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Has the PSU issue on the Mastech been sorted yet? I can find the Mastech for about $180 so I may go for that instead since its true 4w.
Last I heard (a couple of months ago) from Mastech directly, they were only taking away the PSU from the package. No modification to the actual unit. They did mention about removing the DC jack altogether in the future, but not sure if they have taken any real action yet.
I may be biased (because I used to sell them) but I think the MS5308 is a very nice unit other than that power adapter issue. Its size makes it perfect as a bench equipment, though maybe not so much as a handheld device.
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I wouldn't call the LCD readability a major issue. Just a minor hindrance. The CEM meter has exactly the same display quirk, by the way. At right angle, the LCD is a bit blurred, but still readable. At about 15 degrees and more from vertical the readability is normal. The effect is slightly worse with the backlight on, as seen in the pictures. I got used to it very quickly and don't fret about it.
The main deciding factor should be about true 4-wire measurement requirement, at the same time evaluating the MS5308 own peculiarities, like the lack of a proper calibration button, for instance.
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Too bad Uni-T didn't use split jacks like IET. What we really need is a shootout between these... c'mon Dave! :box:
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I wouldn't call the LCD readability a major issue. Just a minor hindrance. The CEM meter has exactly the same display quirk, by the way. At right angle, the LCD is a bit blurred, but still readable. At about 15 degrees and more from vertical the readability is normal. The effect is slightly worse with the backlight on, as seen in the pictures. I got used to it very quickly and don't fret about it.
The main deciding factor should be about true 4-wire measurement requirement, at the same time evaluating the MS5308 own peculiarities, like the lack of a proper calibration button, for instance.
Thank you for your nice review. I was looking at the EIT-5000, but the price is to high for this recently turned electronic hobbyist. The price for your Uni-T is just about right for my playing around. I am building the jim's audio on ebay Krell KSA-100 digital amplifier. I keep reading about impedance in and out of devices and this is what I really needed a LCR meter that has the impedance parameter. Does the UNI-T UT612 offer impence measuring?
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I just purchased one but can't get the USB to work on the computer it does not recognize it.
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You're not forthcoming with details.
What steps did you follow?
What computer did you try installing it on?
What operating software do you use?
From an earlier post (post #2):
'Be aware that I found an incompatibility with my USB Logitech MX mouse, so I have to disconnect it while using the logging software, otherwise the meter is not seen by the PC.'
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I Followed the steps outlined in the instruction manual for the install, I am running windows 7 on an HP laptop I am using the touchpad no mouse. checked for conflicts with other drivers installed and could not find any.
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I'm running a Sony Vaio laptop with MS windows 7. Had to reinstall the UT612 software after I had to reformat the hard drive.
This is what I did:
Install the software from the mini disc.
Remove the USB mouse
Connect the USB cable to the meter then the laptop.
Switch the meter on for USB recognition.
Start the software
Connect any DUT to the meter
Press USB on the meter and 'connection' button on the logging software.
Measurements should appear and start filling the database in the software.
If it still doesn't work, I suspect a conflict on the laptop. I'm not sure how to fix that. I have the same problem as yours with the UT61E logging software. My laptop doesn't see the meter. It is still unresolved.
You could try contacting Uni-t, but I doubt they will be able to help you.
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Can this meter be used for testing polyester capacitors ESR?
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Yes, but the values will be wildly different depending on test frequency.
Polyester capacitor datasheets usually quote a maximum DF (dissipation factor) at a specific frequency.
For instance, a new MKP15 220nF should have a DF below 0.003 at 10kHz, to be in tolerance. The batch I have all measure 0.001.
ESR for the same cap varies between 0.1 Ohm and 10 Ohm, depending on test frequency.
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Nevermind I bought DE-5000 with both test leads. Still waiting for him to arrive, seamed like a much better value then this uni-t.
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What I said earlier applies to any LCR meter, not just the 612.
Prices for the DE-5000 have come down recently, especially from sellers in Japan. If you buy the whole kit though, the values aren't very different. The main advantage of the DE 5000 is its proper 4-wire resistance measurement capability.
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I ran a small test to see how the UT612 fared with 10 small 5.6 Ohms resistors and 2-wire measurements.
I did a fresh calibration and used the plug-in test gizmo provided, to eliminate test leads, with a 100kHz current, which provided the best results.
I used the Gossen 30M and Rigol DM3058 with 4W measurements as control DMMs.
The calibrated Gossen and Rigol are very much together, within 2 mOhms, with a 2 mOhms calibration offset taken off.
The UT612 has a large 22 mOhms offset, otherwise doesn't fare too badly, reading within 7 mOhms of the Gossen, after the 22 mOhms correction.
The offset on your meter could be different of course, depending on original manufacturer calibration.
The offset could also be partially attributed to the 2-wire losses in the blade contacts.
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Great Review!
Based upon your review im either going to get this unit and add my own lithium and a recharge port or im going to wait for a better one to come along that is rechargeable and has a better display.
I really wish the big DMM's came with LSR/ESR.......
What do you think about this one in comparison to the UT601 or UT-50D, is it really worth the price difference?
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The UT601 and UT-50D are very basic meters, but depending on your requirements, may be all you need. They are not proper LCR meters though, lacking frequency selection and not measuring ESR, dissipation factor and Q. Their range is also much narrower.
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K! Thanks! Yea I do mostly DC PSUs and TVs but im one of those people who would rather have the capability just in case. Looking forward to your next review! :)
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Sold my UT-612 on fleaBay. Got tired of positioning the unit "just so" due to the funky display issue as well as a laggy response from one of the push buttons.... I suspect a buss commun. problem (was intermittent). I didn't like the bogus 4-wire clips either.... they shouldn't even be listed as being Kelvin on some of the internet ads selling them. There's no shielding nor proper wiring to the clip halves. I never felt solid about the meter after using it a few times. The Applent AT824 & AT825 cost several more $$ and the quality/performance is far above that of the Unit-T. I now have an Applent AT825.
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The Applent AT825 is more expensive, doesn't power-up or charge from a USB 5V connection and lacks the all important 100kHz test frequency. Not a good trade-off in my book.
Of course, if measuring low value resistors is most of what you do, then a proper 4W system is better. Even then, as I have shown, errors are within 30mOhms on the UT612, which has a best resolution of 1mOhm on the 20 Ohm range.
Shielding is useful for measuring resistor values over 10M with long test leads, but not much else. The UT612 comes with shielded tweezers anyway.
The LCD screen is not an issue really, but if your meter was faulty then I understand your frustrations. I couldn't find your past eBay transaction where you presumably listed the problems with your meter though.
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Take a look at the tables in the back of the Uni-T’s manual. You will see that just like Agilent’s 100 kHz handheld LCR model it doesn’t have much to offer as far as ranges go at its 100 kHz test frequency, and even what it does offer is at a high percentage of error at 100 kHz. The Applent AT's include a regular AC charger. I don't consider a USB charger to be any sort of standard necessity with any test equipment myself or any form of a disadvantage without USB charging. As Applent manufactures a lot of sophisticated battery testing instruments, I imagine they felt it to be safest to not feature USB charging.
-Mark-
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The Applent AT825 is more expensive, doesn't power-up or charge from a USB 5V connection and lacks the all important 100kHz test frequency. Not a good trade-off in my book.
Of course, if measuring low value resistors is most of what you do, then a proper 4W system is better. Even then, as I have shown, errors are within 30mOhms on the UT612, which has a best resolution of 1mOhm on the 20 Ohm range.
Shielding is useful for measuring resistor values over 10M with long test leads, but not much else. The UT612 comes with shielded tweezers anyway.
The LCD screen is not an issue really, but if your meter was faulty then I understand your frustrations. I couldn't find your past eBay transaction where you presumably listed the problems with your meter though.
1. In all practicality, how often does any hobbyist (or even the professional tech for that matter) need to test capacitance at 100KHz? Perhaps some esoteric switching power supply caps? 10KHz is plenty for the most part IMHO and I will quickly trade that seldom needed feature for the bright, color TFT display of the Applent - and a touch display at that!
2. For my needs, 4-wire ohms measurement is better accomplished and trusted using my older Fluke 8085A or my Datron any day, before that from a Uni-T product. I didn't but the UT-612 to measure low value resistance.
3. As for the laggy response of the meter, it's my overall "perception" of it compared to others I've tried. It seems to require more "communications" or measurement time before displaying the results.
4. You have to admit it's peculiar and noteworthy about the viewing angle issue of the LCD display that seems to plague all production units of the UT612. Gosh, even the LCD display of cheapo $3 DMM that Harbor Freight Tools often gives away for free has good contrast at most any angle. So after some use, yes, the UT612's goofy display became an annoyance to me. I don't want to spend time positioning a meter to effectively view it.... especially when all the other test equipment on my bench needn't that silly bit of attention! Appears to me Uni-T decided to gamble and compromise rather than reject the whole lot of LCD displays. Given that, makes me wonder where/how else they may have compromised on that model?
5. As for eBay, the meter isn't truly faulty. I simply don't like it's overall response and the bogus 4-wire clips that are sold under the premise as being Kelvin.
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Not quite.
The inductance measurement has an extra range at 100KHz (20uH), with a resolution of 0.001uH and the same accuracy of 1%+5.
The capacitance measurement range goes down to 200pF for both frequencies with an accuracy of 2%+5.
But it is not only a matter of low ranges, some components have to be tested at 100KHz to properly compare readings to datasheet specs.
That is why high-end LCR meters have a wide range of test frequencies. Some small thin film caps call for a test frequency of 1MHz.
As for the USB connection, it might not bother you to carry an extra wall wart, but it is hard to deny the inconvenience. The safety issue is probably worse for your AC wall charger.
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AFAIK, the UT612 was never advertised as being equipped with a Kelvin connection. The tweezers provided are shielded though and so are the UNI-T clips sold on the internet. Some unscrupulous sellers advertised them as Kelvin, but if you know your meter, it is easy to tell that it has no 4 wire connections: The middle jacks are clearly marked 'GUARD'.
The peculiar LCD screen has been discussed at length. The CEM LCR meter screen is just the same. I really don't think it matters that much, but I understand that some people may be unhappy with it.
I see that some UT612 are available for 120$ or less on eBay now, with free shipping:
http://www.ebay.com/itm/UNI-T-UT612-Multi-purpose-LCR-Meter-Inductance-Capacitance-L-C-R-DCR-Q-D-ESR-/221392747637?pt=LH_DefaultDomain_0&hash=item338c093c75 (http://www.ebay.com/itm/UNI-T-UT612-Multi-purpose-LCR-Meter-Inductance-Capacitance-L-C-R-DCR-Q-D-ESR-/221392747637?pt=LH_DefaultDomain_0&hash=item338c093c75)
And yours of course, with the Kelvin clips ;) :
http://www.ebay.com/itm/Uni-T-UT612-digital-LCR-meter-/171457846139?pt=LH_DefaultDomain_0&hash=item27ebaf1b7b (http://www.ebay.com/itm/Uni-T-UT612-digital-LCR-meter-/171457846139?pt=LH_DefaultDomain_0&hash=item27ebaf1b7b)
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At $120 it's not a better choice the DER EE DE-5000, it has 100KHz?
If we need the 100KHz on the Applent you need to get the AT-826A, not the 825A, that's a jump from $180 to $230, about $100 more than the DE-5000, but the Applent have proper 4 wire measurement.
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The cheapest 826 I can find on eBay costs 330$ + postage:
http://www.ebay.com/itm/NEW-APPLENT-AT826-Handheld-LCR-Digital-Meter-Electric-Bridge-100Hz-100kHz-/290931633508?pt=LH_DefaultDomain_0&hash=item43bce06d64 (http://www.ebay.com/itm/NEW-APPLENT-AT826-Handheld-LCR-Digital-Meter-Electric-Bridge-100Hz-100kHz-/290931633508?pt=LH_DefaultDomain_0&hash=item43bce06d64)
The cheapest 825 goes for 190$ + postage:
http://www.ebay.com/itm/APPLENT-AT825-Handheld-LCR-Digital-Meter-Electric-Bridge-100Hz-120Hz-1kHz-10kHz-/121127135336?pt=LH_DefaultDomain_0&hash=item1c33bd6868 (http://www.ebay.com/itm/APPLENT-AT825-Handheld-LCR-Digital-Meter-Electric-Bridge-100Hz-120Hz-1kHz-10kHz-/121127135336?pt=LH_DefaultDomain_0&hash=item1c33bd6868)
Prices are even worse on Amazon.
The DER EE DE-5000 (full set) sells for 184$ with free postage:
http://www.ebay.com/itm/DER-EE-DE-5000-Fullset-High-Accuracy-Handheld-LCR-Meter-TL-21-22-23-IR-AC-DC-/161418672697?pt=LH_DefaultDomain_0&hash=item25954d7a39 (http://www.ebay.com/itm/DER-EE-DE-5000-Fullset-High-Accuracy-Handheld-LCR-Meter-TL-21-22-23-IR-AC-DC-/161418672697?pt=LH_DefaultDomain_0&hash=item25954d7a39)
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Wytnucls, your right I was looking at euro prices.
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AFAIK, the UT612 was never advertised as being equipped with a Kelvin connection. The tweezers provided are shielded though and so are the UNI-T clips sold on the internet. Some unscrupulous sellers advertised them as Kelvin, but if you know your meter, it is easy to tell that it has no 4 wire connections: The middle jacks are clearly marked 'Guard'.
The peculiar LCD screen has been discussed at length. The CEM LCR meter screen is just the same. I really don't think it matters that much, but I understand that some people may be unhappy with it.
I see that some UT612 are available for 120$ or less on eBay now, with free shipping:
http://www.ebay.com/itm/UNI-T-UT612-Multi-purpose-LCR-Meter-Inductance-Capacitance-L-C-R-DCR-Q-D-ESR-/221392747637?pt=LH_DefaultDomain_0&hash=item338c093c75 (http://www.ebay.com/itm/UNI-T-UT612-Multi-purpose-LCR-Meter-Inductance-Capacitance-L-C-R-DCR-Q-D-ESR-/221392747637?pt=LH_DefaultDomain_0&hash=item338c093c75)
And yours of course, with the Kelvin clips ;) :
http://www.ebay.com/itm/Uni-T-UT612-digital-LCR-meter-/171457846139?pt=LH_DefaultDomain_0&hash=item27ebaf1b7b (http://www.ebay.com/itm/Uni-T-UT612-digital-LCR-meter-/171457846139?pt=LH_DefaultDomain_0&hash=item27ebaf1b7b)
Wow this took off in a day. Its funny because after doing research since the last time I posted I also came to the conclusion to buy the AT825, especially after the video review. I like the Auto and A-B Feature. But I do get what your saying, although cant it share the common Guard and get the relative 4 points of measure as shown in action in the video?, Is the UT612 not just the same?(PIC BELOW) Unless something better comes out I will be buying the AT825 and the UT612(I have a all RED and Black EL Lab :palm: )
(http://i.imgur.com/A7x8Gc9.png)
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The 612 could be modified fairly easily for 4W measurements, but I don't think it's worth the effort, unless that would be your only means of Kelvin measurements or you're bored and are looking for a mod challenge.
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Wytnucls --- that's not my Uni-T meter up for sale --- mine was sold awhile back. Don't rush to assume things.
BTW, Ali Baba has the lowest price for the Applent AT825 It just depends who you contact for a quote..... some vendors even include a copy of the manual in print rather than having to d/l it off the net. If I recall correctly, a friend of mine bought his for under $180 and that included e-packaging from China and a printed manual.
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Wow, what a coincidence...the only UT612 for sale in the US with Kelvin clips and it's not yours. And guess what...he's also selling a Datron 1065A just like yours. Sure you don't have a twin brother? Never mind.
Enjoy the Applent. It's good that it comes with a hard copy of the manual like the meters from Agilent. and I hope it also comes with a magnifying glass to decipher those small fonts. >:D
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Modern day manufacturers, especially those operating out of the orient, have it down to a science with very few exceptions to the rule. You are going to get what you pay for. You can see in my picture of the Applent AT825 circuitry that quite a bit more goes in to it by comparison to the Uni-T LCR, and that in a nutshell is why it costs more.
I should have been clear in my previous post about the Uni-T 100 kHz ranges. The number of ranges isn’t necessarily limited, but the values of capacitors and inductors it can test at 100 kHz are limited to values to where the comparison of the measurements between 10 and 100 kHz would be very negligible, but perhaps of some concern depending on the applications the LCR is used for. This is the same with true 4 wire ohms measurement values. With an LCR it might matter to some, for others 4 wire testing might not be a critical factor. Still, my feeling is it’s a feature every LCR meter should include as a precision resistance measurement tool. Perhaps all LCR’s should have the 100 kHz test frequency be useable at all maximum values in the specifications, but this is where it can get confusing and is a big reason why LCR’s step up steeply in price depending on the usefulness of the LCR at 100 kHz and the values of components it can test at that frequency.
I think a lot of audiophile types see a low priced LCR with the 100 kHz test frequency and think hey, wow, I can test the values of all my esoteric audio E-Caps at a response up to 100 kHz! Cool! The problem is they don’t really look at the specs before buying to see what the capacitor value limits are- they will likely be disappointed in this figure on a low priced LCR that features a 100 kHz test frequency. It’s sort of the same scenario in that the number of megapixels a digital camera has doesn’t necessarily mean it will take the highest quality of digital photos, but putting the high figure there makes for a more impressive selling point. You really have to look at what it is you are getting for the money.
AT825 internals:
(https://fbcdn-sphotos-h-a.akamaihd.net/hphotos-ak-xpa1/v/t1.0-9/1016409_732352736784629_580315329_n.jpg?oh=fea59bc03af01b19dcf143425316980f&oe=54C9F6A5&__gda__=1417960406_f661621b60cb100b539e4f6a0f17c092)
-Mark-
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I have some trouble understanding why an LCR meter consisting of a bunch of tightly packed opamps, transistors and discrete components would be any better than a couple of properly developed and time tested ICs with just a few supporting components around them. After all, that's the way the industry is moving forward, probably at a lower cost, but mostly for higher reliability.
Should your Applent meter fail after the 1-year warranty period, you will have to throw it away and buy another one. If someone fries one of the ICs on any the Cyrustek-equipped meters, there is a good chance that the company will send replacement components on request for free, as reported by one of the members here, just a few months ago.
4W resistance measurement capability is quite rare on a portable 4 1/2 digits instrument, but very common on bench meters with much higher counts and accuracy. Tellingly, the published accuracy for the Applent isn't that great on the 5 Ohm range (1%+3) compared to the 612 20 Ohm range (1%+5).
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It’s sort of the same scenario in that the number of megapixels a digital camera has doesn’t necessarily mean it will take the highest quality of digital photos, but putting the high figure there makes for a more impressive selling point. You really have to look at what it is you are getting for the money.
-Mark-
True - there are many older digital SLR cameras of 4-5 megapixels with quality glass optics that take better images overall than 12+ megapixels using plastic aspherical lenses.
Question: is that foggy area on the pcb of the 825 caused from the camera flash? It almost resembles a part(s) that smoked!
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Enjoy the Applent. It's good that it comes with a hard copy of the manual like the meters from Agilent. and I hope it also comes with a magnifying glass to decipher those small fonts. >:D
The UT612 has it's share of small fonts also. Realize that the Applent's display is a bright, contrasting colors TFT, so distinguishing the fonts is rather easy compared to that of a monochrome lcd display..... worse yet, one that is on the faded side.
Let's not forget the title to this thread is: Review and tear-down of UNI-T UT612 LCR meter Your review of the meter is informative; I was just reporting my view, having owned one, and more from the standpoint of its value per dollar spent. Yes it seems to meet a targeted point of sale with it's low price tag. I view the Applent 824/825 models to be products that affordably bridge the price/performance gap between the lower cost LCR meters and the high cost units.
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It’s sort of the same scenario in that the number of megapixels a digital camera has doesn’t necessarily mean it will take the highest quality of digital photos, but putting the high figure there makes for a more impressive selling point. You really have to look at what it is you are getting for the money.
-Mark-
True - there are many older digital SLR cameras of 4-5 megapixels with quality glass optics that take better images overall than 12+ megapixels using plastic aspherical lenses.
Question: is that foggy area on the pcb of the 825 caused from the camera flash? It almost resembles a part(s) that smoked!
Yes, I did blow it up. I just decided to take the photo before I toss the little piece of junk in to the trash. :D Yes, it's the camera flash. Irony as I mention pictures from digital cameras earlier.
Take a look at the other products Applent produces, and their other higher end LCR's. You will notice the company isn't in to the $3.00 throw-away multimeter market. I’m fairly safe in saying Applent’s designers could put the entire handheld LCR circuit on a few chips if they wanted to design them that way. But rather than do that, they picked much of their handheld LCR circuitry and features from their more upscale models. Things are done a certain way for reasons, even things as simple as protection diodes that cost a little extra in production. If that were false, the LCR’s from industry leader Agilent would look like a Uni-T inside also- which they don’t.
The made in China point is moot when or if it comes to service . Will I have to throw the Applent away if it fails out of warranty? That I don't know for sure. I also wouldn't know that answer for sure if I owned a Uni-T. Time will tell all, that is why I did the thread on the AT825. My intent isn't to steal this thread, only to show how another example of an LCR in this same price range is made and/or how it differs. I did notice from earlier reading here at EEVBlog that Uni-T is sort of leading the way in the Multimeters that do not appear to meet their safety specs thread though, which is not uncommon to things made with the most cost-cutting at the heart of the design.
-Mark-
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It’s sort of the same scenario in that the number of megapixels a digital camera has doesn’t necessarily mean it will take the highest quality of digital photos, but putting the high figure there makes for a more impressive selling point. You really have to look at what it is you are getting for the money.
-Mark-
True - there are many older digital SLR cameras of 4-5 megapixels with quality glass optics that take better images overall than 12+ megapixels using plastic aspherical lenses.
Question: is that foggy area on the pcb of the 825 caused from the camera flash? It almost resembles a part(s) that smoked!
Yes, I did blow it up. I just decided to take the photo before I toss the little piece of junk in to the trash. :D Yes, it's the camera flash. Irony as I mention pictures from digital cameras earlier.
Take a look at the other products Applent produces, and their other higher end LCR's. You will notice the company isn't in to the $3.00 throw-away multimeter market. I’m fairly safe in saying Applent’s designers could put the entire handheld LCR circuit on a few chips if they wanted to design them that way. But rather than do that, they picked much of their handheld LCR circuitry and features from their more upscale models. Things are done a certain way for reasons, even things as simple as protection diodes that cost a little extra in production. If that were false, the LCR’s from industry leader Agilent would look like a Uni-T inside also- which they don’t.
The made in China point is moot when or if it comes to service . Will I have to throw the Applent away if it fails out of warranty? That I don't know for sure. I also wouldn't know that answer for sure if I owned a Uni-T. Time will tell all, that is why I did the thread on the AT825. My intent isn't to steal this thread, only to show how another example of an LCR in this same price range is made and/or how it differs. I did notice from earlier reading here at EEVBlog that Uni-T is sort of leading the way in the Multimeters that do not appear to meet their safety specs thread though, which is not uncommon to things made with the most cost-cutting at the heart of the design.
-Mark-
Hey hey hey wait now, I would be more than happy to buy that toasted one off of you for spare parts! :-+
Also how did you toast it in the first place?
Also the Chinese manufacturers are not all bad, Japan either. As a matter of fact the beloved Fluke and other brands are also made there :-DMM
Now speaking from experience in import, export, and wholesale, the actual manufacturers are good at making their customers happy. The problem is the middle men, the drop shippers and suppliers that you all deal with, they are NOT a reflection of the company. For many manufacturers they are working their way up and do not have a robust customer service department that speaks various languages, thats why they choose to only freight to resalers and suppliers. I have found that it is fairly easy to get what you need when you need it via DHL in 3 days from China if you talk to the right person!!! :scared:
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MCCSolutions - I think you missed the part where M. Palmer said the smokey appearance is due to the camera's flash reflecting off the pcb.
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MCCSolutions - I think you missed the part where M. Palmer said the smokey appearance is due to the camera's flash reflecting off the pcb.
Yea I know, I think he was being sarcastic but you never know lol :-//
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Hello, joined this forum to say thanks to all who posted photos of this lcr meter, I screwed mine today by accendentally putting 120vac on the inputs (long story)... I managed to repair it with the help of the photos posted here, 3 smd input resistors R1, R11, R10 where burned and chared, replaced them and crossed my fingers and yes!!! Got it working again, thanks guys...
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Good review. It's already a few years ago from now.
But do actual batches have the same weakness in LCD display? I mean that viewing angle.
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Anyone managed a successful 4wire mod on this? Looking at those PCB traces it does look eminently doable.
I'd be more interested in that than the guard - I regularly want to measure resistances below 1ohm, whereas I don't think I've ever cared about anything bigger than 100k, let alone a meg. Having 4 wire would definitely count more than guard, so I think I'd just repurpose those two guard sockets into 4wire mode instead.
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Dissipation Factor (tan D) max values chart.
Update 18May2017
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Added more capacitors + LoadLife values
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Thanks Pr0metheus.
Useful table f0r tr0ublesh00ting. ;)
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Great review, was thinking about getting one and after the review I'm going for one.
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In conclusion, really matter the 4W of DE-5000? really has more accuracy than UT612? DE-5000 is not comes with 4W probes, in my country the price difference between DE-5000 and ut612 is around 30 usd more for DE-5000, but ut612 comes with all accesorys and case. The 4W improves accuracy only on DC resistance test? I have a 4W bench meter with this function.
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After going through different boards here to get a better understanding of this LCR thing I decided for a brand new UNI-T UT612.
Thanks for all the efforts and advices in this board during the last years. In the beginning I considered a DE 5000, but after reading the tests of Wytnucles
and the long Youtube video of DefProm I go now with the UT. It seems to have the same chip set but looks much fresher ;-) than the DE-5000. (btw: the DE-5000 is till now only available
via direct import from Japan or the USA, the risk of import taxes is given)
The UT612 is a big improvement over my old Atmega based 10€ LCR meter! For my hobby needs it should be ok.
I don't have any planning to run a calibration shop :-// (as some others when I read the postings here)
Since I own a decent DMM (34401A) with Kelvin clamps for R (as many others I'm sure, no one buys a LCR meter as first device) I do not really care about the wide and broad discussed
pros and cons of 4W measurements with all the named devices.
It came as described in a plastic box and all the adaptors and cables. Build quality is good for that price point (130€) and it came from a german reseller. (PinSonne Elektronik)
It has a good LCD screen now (2020). The earlier (years ago) mentioned weaknesses of it are not noticeable.
It does the job!
Thanks again for all the efforts, tips and hints here!
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post the pic man :clap: :-+
also pic of lcd too.. :popcorn: :popcorn:
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Sorry found your request to late. After some month using the meter all works for me.
I use it for caps and inductivites. Low res measurements isn‘t important for me since I have a HP34401A
with 4wire measurement and kelvin clamps on the bench.
The only downside of the meter are the terrible tips of the tweezer. They are to soft, you need to much pressure to get good contact for calibration and you bend them. And it is hard to get good contact on the pcb. They
should be better gold plated.
I‘m looking for a better solution but are short of time these days.
If some one has a good idea how to improve the tweezer it will be highly appreciated!
PS no clue why the pics are downside :-//
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I don't know what to do about the tweezers but there is a part called UNI-T UT-L61 which is a pair of clips that might be useful to you.
Better late than never?