Author Topic: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown  (Read 25388 times)

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Offline Spawn

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #25 on: May 08, 2013, 11:46:31 pm »
Interesting teardown, they put a lot more stuff into this than in the UT511, which I own. The UT511 only goes up to 1000V and is approx. 80 EUR. Attached is a photo of the main pcb for comparison:

HUGE difference!, thanks.

Yeap it is totally different, the 511 is a lot cheaper doesn’t have USB connection and missing a lot more, here some more pictures and a video from my preview:
https://www.eevblog.com/forum/testgear/uni-t-ut511-insulation-tester-unboxing-and-preview/

Thanks for the nice teardown Dave :)

Offline retiredcaps

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #26 on: May 09, 2013, 12:17:34 am »
@Dave,

Someone is already stealing your video and uploading it as his own.

https://www.youtube.com/channel/UC9gt4SbTnoiXsQ3NkeObKnQ/videos
 

Offline EEVblog

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #27 on: May 09, 2013, 12:53:21 am »
Someone is already stealing your video and uploading it as his own.
https://www.youtube.com/channel/UC9gt4SbTnoiXsQ3NkeObKnQ/videos

Thanks.
Complaint submitted.
 

Offline MBY

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #28 on: May 09, 2013, 12:27:41 pm »
I have a UT 511 and decided to follow Daves request and do a short teardown. I did it yesterday but now I'm too late since Entropys post! :( :)

Anyhow, I can confirm that my unit does look the same as Entropy's.

The UT 511 is a insulation tester with 100, 250, 500 and 1000 V test voltages. It ALSO has the problem of just dying or locking up at random, often just on the 1000 V range.

People in the thread has suggested EMI and thats probably what happens. But my idea before was peak current and undervoltage cut out. My unit got better with new alkaline batteries instead of the included crappy "heavy duty" zinc-carbon ones.

Has anybody tested with the AC adapter? Do the unit shows random lockup or shutdowns at higher voltage (and, presumably, arcing) even when powered from AC?

Another question: What does the USB interface do? Its one-way from the unit to the PC, so I presume its just a serial link with data? The UT 511 doesn't have a USB interface, but it has the same PCB (I show you in the pics), but the USB part it non populated. Is there any reason to try to populate it? I can perhaps test by mounting a visible light LED on the transmitter.

Edit: The forum went unreachable during posting. The images disappeared.

Edit: I was quite disappointed. I was hoping to touch the interesting potting compound! :(

Edit: To clarify. The attached images shows a closeup of the HV part and the DC-plug/USB-interface card.
« Last Edit: May 09, 2013, 01:23:11 pm by MBY »
 

Offline gotnoise

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #29 on: May 09, 2013, 01:34:36 pm »
I would like to understand the purpose of the shielding tape. Shouldn't an EMI shield be connected to ground? Or does a "floating" shield help as well?
 

Offline MBY

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #30 on: May 09, 2013, 01:47:55 pm »
Is the forum okay? This is my third attempt to post this message!  :-//

I have a UT 511 and decided to follow Daves request and do a short teardown. I did it yesterday but now I'm too late since Entropys post! :( :)

Anyhow, I can confirm that my unit does look the same as Entropy's.

The UT 511 is a insulation tester with 100, 250, 500 and 1000 V test voltages. It ALSO has the problem of just dying or locking up at random, often just on the 1000 V range.

People in the thread has suggested EMI and thats probably what happens. But my idea before was peak current and undervoltage cut out. My unit got better with new alkaline batteries instead of the included crappy "heavy duty" zinc-carbon ones.

Has anybody tested with the AC adapter? Do the unit shows random lockup or shutdowns at higher voltage (and, presumably, arcing) even when powered from AC?

Another question: What does the USB interface do? Its one-way from the unit to the PC, so I presume its just a serial link with data? The UT 511 doesn't have a USB interface, but it has the same PCB (I show you in the pics), but the USB part it non populated. Is there any reason to try to populate it? I can perhaps test by mounting a visible light LED on the transmitter.

Edit: The forum went unreachable during posting. The images disappeared.

Edit: I was quite disappointed. I was hoping to touch the interesting potting compound! :(

Attached is a close up of the HV parts and the DC-jack/USB-interface PCB.
 

Offline jnissen

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #31 on: May 09, 2013, 02:40:08 pm »
Dave, great tear-down but please use the proper terms. You mentioned  couple times in the video and also in other video's that this or that was done to knock down the "EMC". You can't change the compatibility levels on a whim! You can however change the interference or "EMI" that comes from the product. I've made the same mistake in the past and had the long version of the discussion delivered to me by a crusty old EMC testing facility engineer. Those guys take it personally when you don't use the proper terms!
 

Offline MBY

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #32 on: May 09, 2013, 03:07:15 pm »
Now I soldered a LED on the unpopulated PCB and connected it to a photodiode in a heat-shrunk tube. Total bummer. The LED lits on key press (along with beeps) and it is steady on during a key press. So no serial data and only a level change. Clearly the SW has disabled serial output on this model.

Attached is a picture of the LED/photodiode "tube" and a scope screen shot showing a key press.
« Last Edit: May 09, 2013, 03:18:30 pm by MBY »
 

Offline nitro2k01

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #33 on: May 09, 2013, 05:33:19 pm »
Hmm, have you tried flipping the polarity of the LED? It's a bit of a stretch, but maybe the unit keeps the diode reverse biased when idle, and then when it's transmitting it goes between trying to sink current through the LED and high impedance.  This would explain why it's lit when idle and off while transmitting, if you have the LED in reverse. just a thought. (Oh, it's on when you press the button. Nevermind.)
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Offline lapm

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #34 on: May 09, 2013, 06:28:29 pm »
These things usually aren't used to generate sparks though  >:D

Oh, come on! That's the first thing you do when you have something that puts out 5 kV!

 :-DD, first thing i would do with high voltage dc source. Sparks...

BTW we need some sort of sparcky as smiley in here :P
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Offline M0BSW

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #35 on: May 09, 2013, 06:51:01 pm »
 VC99, As some of you know Ive been measuring the voltage on my VC99, which has been dropping a volt per month even with fresh batteries, well it died tonight, and I thought I'd take a look, instead of the small ceramic fuse and a large ceramic fuse, they fit two stupid thin lame arsed glass fuses in them, glad I never went near the mains with it, anyway it's dispatched in the bin now ready for land fill tomorrow , see even a VC99 has it uses, I suppose in won't rot in the land fill will it, the bugger will still be there when I'm dead and gone  Grrrrrrrr
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Offline karan279

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #36 on: May 09, 2013, 07:31:37 pm »
The usb IC on there appear to come from this chinese manufacturer http://wch-ic.com/ , though this particular part no isn't listed , but one of their usb to serial IC , CH340 is common and about half a $ :) 
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Offline jesuscf

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #37 on: May 10, 2013, 03:06:41 am »
The usb IC on there appear to come from this chinese manufacturer http://wch-ic.com/ , though this particular part no isn't listed , but one of their usb to serial IC , CH340 is common and about half a $ :)

Beware of the CH340 and friends!  It is poorly (as non-existent) documented and there is only a complete driver available for Windows.  The driver for Linux is semi-functional and zero drivers for Macs.
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Offline jesuscf

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #38 on: May 10, 2013, 03:14:05 am »
I'm developing software for these Silabs MCUs (that means, I "have to"), they have an crusty old 8051 core tweaked with more peripherals and a higher clock (usually up to about 25 MHz and single cycle instructions)...

Edit: The f352 used in the unit can run at 50 MHz

What MCU would you use instead?  I ask because I used a C8051F352 a few years back and it worked very well.
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Offline karan279

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #39 on: May 10, 2013, 06:03:07 am »
Quote
Beware of the CH340 and friends!  It is poorly (as non-existent) documented and there is only a complete driver available for Windows.  The driver for Linux is semi-functional and zero drivers for Macs.

Thanks for that info , most of these cheap ones don't have anything other than a windows driver and that too not reliable at all
« Last Edit: May 10, 2013, 06:05:56 am by karan279 »
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Offline amyk

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #40 on: May 10, 2013, 01:02:02 pm »
The UT511 HV section looks similar to that of a CCFL inverter, not surprising given the max of 1kV.
 

Offline Neilm

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #41 on: May 10, 2013, 06:17:01 pm »
Dave - If you really want some sparky fun get a 10kV tester and put it across an old CD. You get LOTS of sparks as the oxide burns off the plastic  :D Probably won't work too well with only 5kV.

Its also a good way too see how immune your tester actually is. These testers are often used to burn out small manufacturing defects in equipment when it is under test so a tester that dies during this sort of test will cause all sorts of problems.

For those interested, the 10kV instrument I was testing when I did the above with the CD quite happily carried on working and burnt out the oxide.

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Offline KD0CAC John

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #42 on: May 10, 2013, 06:24:31 pm »
I've got couple of older Meger units , one is just AC - 4,000 volts and the other is AC / DC 6,000 volts .
Got them both needing miner repairs .
I got them because I was getting more & more used vacuum variable caps that I wanted to know if they were good .
 

Offline T4P

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #43 on: May 10, 2013, 07:58:00 pm »
No wonder there's such a huge disparity in price between UT511 and 513!
The 511 IMO is not even worth the money it is going for but the 512 and 513 is  :-//
I did consider them before i left for the PC world because of it's MASSIVE screen and how it looks so i guess, until i earn some money and get my computer upgraded ... sadly i'm not getting my hands on one of these, i love it! But ... No application or use for  :-DD Maybe blowing up old hardware  >:D So yes my U1273AX is sitting there with nothing to do  :-DMM
 

Offline T4P

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #44 on: May 10, 2013, 07:59:54 pm »
Dave - If you really want some sparky fun get a 10kV tester and put it across an old CD. You get LOTS of sparks as the oxide burns off the plastic  :D Probably won't work too well with only 5kV.

Its also a good way too see how immune your tester actually is. These testers are often used to burn out small manufacturing defects in equipment when it is under test so a tester that dies during this sort of test will cause all sorts of problems.

For those interested, the 10kV instrument I was testing when I did the above with the CD quite happily carried on working and burnt out the oxide.

Neil

What sort of defects?   ;D I think if you position the meter further away it might not crash. Could be because of low current supply from those weak batteries  :-//
 

Offline Fezder

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #45 on: May 11, 2013, 01:14:01 pm »
nice teardown, bigger one relay :D
Both analog/digital hobbyist, reparing stuff from time to time
 

Online SeanB

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #46 on: May 11, 2013, 01:50:40 pm »
I normally erase CD's and DVD's in the microwave. 20 seconds and the pile is unusable. If I had access to that method of Photons though............
 

Offline larry42

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #47 on: May 12, 2013, 12:14:03 pm »
When I got the UT513 some time ago I wondered why it hat a E-STOP, you could just push the TEST button to turn it off, it is larger and it is illuminated.
First time it arced over, I found out why. The E-STOP is the only button that always works.
It might have a nice hardware design, but I do not like that the microprocessor locks up when it arcs on 5000 volt (I have not seen it on 2500 volt).

My UNI-T UT502 always has voltage on the output connection - regardless of the "TEST" button. Which is not good on a 2500V tester (Have to switch to DCV to prevent getting shocked). Anyone got a schematic for me to try and fix this UNI-T P.O.S.?

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Offline Phantomix

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Re: EEVblog #468 - Uni-T UT513 Insulation Resistance Meter Teardown
« Reply #48 on: May 12, 2013, 04:05:27 pm »
I'm developing software for these Silabs MCUs (that means, I "have to"), they have an crusty old 8051 core tweaked with more peripherals and a higher clock (usually up to about 25 MHz and single cycle instructions)...

Edit: The f352 used in the unit can run at 50 MHz

What MCU would you use instead?  I ask because I used a C8051F352 a few years back and it worked very well.

Hi! Don't get me wrong, sure these chips work, and if you prefer them that's fine :-) I was just a little frustrated by the limitations of the old 8051 core...

So, which MCU should be used in a commercial project? the one that fits best. This also includes development time - sometimes, for example if it is commonly used in your company, it's better to stick with an old 8051 architecture instead of moving to a more modern one.

I personally prefer the STM32 ARM Cortex for connectivity and calculation tasks, or the STM8 for "as-cheap-as-possible" tasks. I also worked with MSP430 which seems to be a nice architecture, and AVR. The thing with AVR is that there's no good debugging standard for all chips (I'm talking On-Chip-Debugging here)... It also lacks the ability to run Code from RAM (which is possible with STM8, for example)

The 8051, and especially the ones delivered by Silabs are, in my opinion, the worst architecture:

Limitations of the 8051 core:
- Not a linear memory model (e.g. you have multiple memory areas starting at Address 0: DATA, PDATA, XDATA, ...)
- Only one Accumulator register that has to process all data
- Small Stack pointer - limited to the lowest 128 Bytes of Data RAM
- Limited amount of 128 SFR (Special Function registers) for all peripherals
- Inefficient access to all RAM above 256Bytes (XDATA)

Limitations of the Silabs 8051:
- The Silabs Crossbar is a nice idea for flexible pin assignment, but most times it makes the project more complex without real benefits.
- They stuck with the old 8051 UART, which uses TIMER1 as time base
- They use Paged SFR access (you have to write to the SFR_PAGE register before you can access the desired SFR) this makes coding harder
- Very limited capabilities of PWM output (pwm frequency). Silabs statement from their datasheets: For a PWM, it doesn't matter how fast it is, as long as the on/off proportion is right.

Limitations of the Keil C51 compiler:
- Data overlays are a good idea to make the best effort of the limited amount of Data RAM
- Function pointers work, as long as the target functions don't use local variables (Overlay screwed up)
- Sometimes, changing variables that are function parameters will result in unpredictable results.
- Reentrant functions are problematic, that means if a function is called from normal code, and then from an interrupt, it also can screw up your variables.
 

Offline iXod

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Re: EEVblog #468 - AC adapter issues for N. America
« Reply #49 on: May 14, 2013, 08:00:08 pm »
Looks like all listings of this meter model on U.S. e-Bay do not include the AC adapter (extra USD 35).

And it looks like the adapter is 220v only!
« Last Edit: May 14, 2013, 08:03:05 pm by iXod »
 


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