Author Topic: Vichy VC99 Multimeter Review and Teardown  (Read 80157 times)

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Offline Simon

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Re: Vichy VC99 Multimeter Review and Teardown
« Reply #75 on: November 22, 2012, 07:17:33 pm »


I just think hyperbole and categorical statements, without any context about what the device is being used fo, is as daft and juvenile as Mac vs PC vs Linux debates.

The "context" you refer to, was just trying to turn the damn thing on !, then trying to measure a resistance with any degree of acuracy and without unrealistic delays in making it's mind up to what the reading will be. Is that self explanatory enough ???
 

Offline johansen

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Re: Vichy VC99 Multimeter Review and Teardown
« Reply #76 on: August 21, 2013, 07:09:58 am »
I've used two of these meters for about 2-3 years now and i have to say that although they are the cheapest 5999 count mulitmeters on the planet, and i've had some issues with them, i would rather buy 10 of these meters than 1 of the well known 40,000 count Fluke equivalents.

After discovering that the 10 amp Shunt is actually only a meagre 5 milli-Ohms, i drilled two holes in the back of the meter and glued a terminal strip to the back and soldered #12 wires from the terminal strip to the shunt.
that 0-10 amp range is really 0-60 , however an external 5 milliamp shunt rated for 60 amps would be required. either that or divide by 10 would be more reasonable.

The 0-600mA range is really a .48 ohm resistor with a couple others in series (unsure) both have burden voltages of .3 volts. meaning full scale current is 0.3 volts drop. the meter leads it comes with are 24 gauge or smaller.. 0.5 ohms is about what you'd expect, and what's a banana plug between friends (if you know Kelvin? ehehehe)

oh, btw, take out the current shunts and you have a microvolt volt meter.

i have nothing to complain about, it runs on rechargeable AAA batteries just fine.
the ohms measurement could have easily delved past .1 ohms....
but to do that i just use two meters, a D cell battery and a calculator.



« Last Edit: August 21, 2013, 10:18:54 pm by johansen »
 

Offline ddavidebor

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Vichy VC99 Multimeter Review and Teardown
« Reply #77 on: August 21, 2013, 08:46:29 am »
You say that because you can't afford a fluke prrrrrrrrr
Davide Bortolami,
Fermium LTD
 

Offline johansen

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Re: Vichy VC99 Multimeter Review and Teardown
« Reply #78 on: August 21, 2013, 08:08:33 pm »
i am a cheap bastard.

btw, those cheap 100g/500g/1Kg drug scales on ebay are really 2.4uV to 2.4mV volt meters connected to a strain gauge.

couple that to a precision 2.4/24/240mA current source and you have a 1 micro ohm to 1 ohm resistance measurement device ... much cheaper than a professional micro ohm meter and just as accurate. kelvin clips are on ebay for a couple bucks.
 

Offline KARADENIZ

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Re: Vichy VC99 Multimeter Review and Teardown
« Reply #79 on: August 21, 2013, 09:36:32 pm »
if 6000 counts are ok, I think vichy vc99 is for 32$  http://goo.gl/Z5WJfr a good choice because of its accuracy.
Vichy has the same chip like Uni-t UT61B, UT61C und UT61D (Chip FS9922-DMM4) http://goo.gl/ARBWZ2
« Last Edit: August 21, 2013, 09:38:48 pm by KARADENIZ »
 

Offline johansen

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Re: Vichy VC99 Multimeter Review and Teardown
« Reply #80 on: August 21, 2013, 10:26:27 pm »
interesting, i edited my post, i've been using these things for 2 years and never noticed they are 6000 count lol.

i wonder if there is some way to modify the ohms scale for 1/10th the value. meaning boost the current source 10 fold.
 

Offline johansen

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Re: Vichy VC99 Multimeter Review and Teardown
« Reply #81 on: August 21, 2013, 11:56:02 pm »
well i figured out how to multiply the 600 ohm and the 6000 ohm readings 10 fold.
and divide the 6000 volt range by ten.

There is a small problem of auto ranging does not work when the meter attempts to change the range between 6000 and 60,000 ohms.
Take resistor 25 in the datasheet which is connected to pin 21 of the chip and solder in a 112ohm resistor across it, to make it 100 ohms vice 1K

when you take the back of the meter off, you'll see a variable resistor accessible through a small hole in the board, in the top left corner next to what looks like a DIP-8, but its not a DIP-8, it is 4 resistors. you can measure them to identify them, as 1M, 100K, 10K and 1K, or you can take my word for it, (the bottom one is 1K. you'll need a 112 ohm resistor to make it 100 ohms.

I tried to use a 10 ohm resistor, but the meter is unstable, the "resolution*" means that you're going to be reading either 110 or 95 ohms, for a 1 ohm resistor. *remember we're dealing with microvolts here
« Last Edit: August 21, 2013, 11:57:35 pm by johansen »
 

Offline Smokey

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Re: Vichy VC99 Multimeter Review and Teardown
« Reply #82 on: April 29, 2015, 12:33:38 am »
Guys ,
 Do Some of you share simons viewpoint ? ,BTW Simon i Have the Vichy VC97 Would Like To Give a Teardown Too  .

What is the difference between Vichy VC97 and VC99? Is the VC97 good enough compared to the small improvement?

Any update on current measurement precision and autoscaling? Is it improved in VC97+?

The quick answer is that if you can't figure this stuff out it really won't matter.... and you probably will be better off not buying a crappy VCanything. 
 

Offline Smokey

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Re: Vichy VC99 Multimeter Review and Teardown
« Reply #83 on: April 29, 2015, 12:57:43 am »
Is a turd with 10 flies on it an improvement on a turd with only 5 flies on it?
(And yes I know I posed positive stuff about these meters earlier in the thread, but I also acknowledged the turd-ness then too.  Even turds are useful sometimes...)
 

Online pascal_sweden

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Re: Vichy VC99 Multimeter Review and Teardown
« Reply #84 on: April 29, 2015, 08:01:32 am »
I found the specs for VC99 on DealExtreme.

Apparently it is 3 6/7 multimeter, with 6000 readings.
Still no backlight. Was hoping for the latter.

However I still have a question: if the highest number on the display is 5999.
How does this work out when measuring 1000V and what is the accuracy?

It is easy to understand for 600mV, 6V, 60V, 600V ranges, but how does it work out for the upper range between 600V and 1000V?  How is that represented on the screen?

Other question: the precision of the multimeter is not only defined by the number of digits but also by the number of samples that are taken and averaged.
How do these meters perform here in relation to a real Fluke?

And what about the sample rate?

If I am correct, multimeters can be characterized by safety on inputs, sealing of housing to keep blast inside, number of digits, number of samples that are taken and averaged, and actual sampling rate.

« Last Edit: April 29, 2015, 08:06:36 am by pascal_sweden »
 

Offline rolycat

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Re: Vichy VC99 Multimeter Review and Teardown
« Reply #85 on: April 29, 2015, 08:42:03 am »
I found the specs for VC99 on DealExtreme.

Apparently it is 3 6/7 multimeter, with 6000 readings.
Still no backlight. Was hoping for the latter.

However I still have a question: if the highest number on the display is 5999.
How does this work out when measuring 1000V and what is the accuracy?

It is easy to understand for 600mV, 6V, 60V, 600V ranges, but how does it work out for the upper range between 600V and 1000V?  How is that represented on the screen?
The resolution is 1V between 600V and 1000V, and accuracy is given as 0.8% +3 counts in the manual (which is readily available online, btw).

Quote
Other question: the precision of the multimeter is not only defined by the number of digits but also by the number of samples that are taken and averaged.
How do these meters perform here in relation to a real Fluke?

And what about the sample rate?

If I am correct, multimeters can be characterized by safety on inputs, sealing of housing to keep blast inside, number of digits, number of samples that are taken and averaged, and actual sampling rate.
And many other things.

Why are you so interested in junk like the Vichy meters? The Uni-T UT139C can be bought for a similar price and reportedly offers much better build quality. It also has a backlight and true RMS.
 

Offline sync

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Re: Vichy VC99 Multimeter Review and Teardown
« Reply #86 on: April 29, 2015, 08:48:52 am »
Other question: the precision of the multimeter is not only defined by the number of digits but also by the number of samples that are taken and averaged.
I don't think it takes several samples and average them for a reading. This is unusual for DMMs like this. They just using a dual slope ADC which gives the reading directly. Thus one sample per reading.

Quote
And what about the sample rate?
From the specifications: ~3 samples/s.
 

Online pascal_sweden

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Re: Vichy VC99 Multimeter Review and Teardown
« Reply #87 on: May 01, 2015, 06:37:40 pm »
Why are you so interested in junk like the Vichy meters? The Uni-T UT139C can be bought for a similar price and reportedly offers much better build quality. It also has a backlight and true RMS.

I needed a cheap multimeter for low voltage measurements that is accurate.
From the review video of Martin Lorton, I learned that the Vichy is quite accurate, and therefore I decided to go and buy it.

I happened to buy the Vichy VC97+ from AideTek on Ebay.
Recently I found out that there is a VC99 out there as well, and I was curious about the difference.

I did miss out on the absence of the backlight, when buying the multimeter.
However I was convinced that the meter has True RMS, and I really hope that it does.
On some forums there is an indication that the VC97+ version has True RMS.
« Last Edit: May 04, 2015, 09:41:01 pm by pascal_sweden »
 

Online pascal_sweden

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Re: Vichy VC99 Multimeter Review and Teardown
« Reply #88 on: May 04, 2015, 09:41:17 pm »
If HRC fuses are that much better, can't you just replace the glass ones in a normal meter with HRC fuses of the same size and ratings? Or is there something special there that would make this not possible?
 

Offline Lightages

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Re: Vichy VC99 Multimeter Review and Teardown
« Reply #89 on: May 04, 2015, 11:04:37 pm »
There are so many things that go into the safety design other than just the types of fuses. There is spacing of traces, clearance between parts, ratings of components, and the design of the case and plastics. You can change the fuses to higher rated fuses but this is no guarantee that it increases the actual safety of the meter. It certainly will not degrade the safety but it is only going to make you feel better.

Some meters obviously benefit from installing an HRC fuse and at least one manufacturer has done this to some meters being sold in the EU but also have had to derate their meters to lower CAT ratings than they had originally.
 

Offline rolycat

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Re: Vichy VC99 Multimeter Review and Teardown
« Reply #90 on: May 04, 2015, 11:08:41 pm »
If HRC fuses are that much better, can't you just replace the glass ones in a normal meter with HRC fuses of the same size and ratings? Or is there something special there that would make this not possible?

A normal meter has HRC fuses. IEC regulations now require them in all new meters.

Replacing the glass fuses in cheap meters is possible - you can get 1500A breaking capacity HRC fuses in the 20x5mm size. They are highly unlikely to meet this specification if fitted in such a meter, though. If you are intending to work with high energy circuits it would be better to save your money and put it towards a safe meter.
 

Online pascal_sweden

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Re: Vichy VC99 Multimeter Review and Teardown
« Reply #91 on: May 11, 2015, 01:45:11 am »
Interesting question: How much extra would a Chinese multimeter cost, when they make the design more safe? Let's say the price to make something safe is 100 USD, then the Chinese companies would still be able to provide a competitive product, given that their meter costed 25 USD before, and would now cost 125 USD. They could make a "gold" edition of their multimeter :)
 

Offline johansen

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Re: Vichy VC99 Multimeter Review and Teardown
« Reply #92 on: May 13, 2015, 12:34:21 am »
it would cost whatever it takes to redesign the injection mold.. considering they probably stole it from someone else.

it would cost whatever it takes to redesign the circuit board to provide room for a proper fuse.
and it would cost 2$ more for a fuse.

maybe another 10 cents for some movs and better resistors.
 

Online pascal_sweden

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Re: Vichy VC99 Multimeter Review and Teardown
« Reply #93 on: May 13, 2015, 10:33:24 am »
So that really confirms that the A-brands are overpriced.

Basically you can make the safest digital multimeter in the world for only 50 USD.

I wonder what the big companies have to say over that? Maybe it's time that their Royal Reign is over.
 

Offline rolycat

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Re: Vichy VC99 Multimeter Review and Teardown
« Reply #94 on: May 13, 2015, 10:58:25 am »
So that really confirms that the A-brands are overpriced.

Basically you can make the safest digital multimeter in the world for only 50 USD.

I wonder what the big companies have to say over that? Maybe it's time that their Royal Reign is over.

Tosh.

As johansen pointed out, they could make a somewhat safer meter by copying features from a decent brand, but it's not going to be "the safest in the world", and certainly not for $50.

Chinese companies competing principally on cost will always skimp on safety, build quality and anything else they can get away with.

If you want a safe, well engineered multimeter without paying the "Fluke premium", buy a Brymen. They are even Chinese, albeit the Republic of China.
 

Online pascal_sweden

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Re: Vichy VC99 Multimeter Review and Teardown
« Reply #95 on: May 13, 2015, 11:53:02 am »
I am considering the Brymen 869s:
http://www.brymen.com.tw/product-html/cata860/Bm860L3.htm

But what is the difference between Brymen 869s and Brymen 869?
 

Offline Lightages

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Re: Vichy VC99 Multimeter Review and Teardown
« Reply #96 on: May 13, 2015, 12:36:58 pm »
From a VC99 to a BM869s?  :-+

The "s" version is just the latest updated model to comply with the latest safety standards.
 

Online pascal_sweden

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Re: Vichy VC99 Multimeter Review and Teardown
« Reply #97 on: May 13, 2015, 03:00:36 pm »
I will still buy some extra Vichy VC97's. The Vichy VC99 is not much better than the VC97, and I like the dial options better on the VC97.

For some test experiments it's good to have several multimeters at hand, so that you can keep them connected to different test points.

It would be overkill to buy 5x Brymen BM869s units, moreover unaffordable as well :)

It will do with one Brymen BM869s. I can always use it as a reference to double check the accuracy of the other cheap bastards lying around :)

Brymen seems to be a good company. Exactly the company which I have been looking for. Fluke quality at an affordable price. In fact I believe the design is very good looking, and definitely same or even better than Fluke, but then again, this is personal opinion and taste.
« Last Edit: May 13, 2015, 03:04:11 pm by pascal_sweden »
 


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