Product review: DMM latest V&A Mastech VA18B

[Kiriakos-GR]

Due special circumstances, the detailed review will follow in few hours,
the first wave will be the pictures of the Tear-down.

But here is a small introduction,
I had send a message to Mastech before two weeks, so to offer to me one of their latest high-tech  units for review.
The reason that I did that can be explained here .. https://www.eevblog.com/forum/index.php?topic=4825.0
After of two weeks of silence from their side, I lost hope that they will respond.
Probably because I discovered even at the 2011 many Chinese brands lacks of innovative products,
read here the rest of the story.  https://www.eevblog.com/forum/index.php?topic=4913.0

Luckily I found one of those  V&A Mastech VA18B locally, one close friend of my got one,
and what I did was to actually snatch it for a review.

The unit is stamped with the logo of a Greek company, that is a known major retailer in Athens.
Re-branded by Greek distributor.

By looking the pictures of the Tear-down, the first impressions are terrible, there is no need to say that most of my enthusiasm about it had vanish.
Even so, I will do several measurements, and I will report my findings in few hours.
The manufacturing quality is terrible in my eyes.
I do not know who awarded it at 2006,  the award logo does not point to the source.
But either way I will try to find how bad is it in action, and this is all that I will do.

The specific model retails at 40 EUR, equal to the 50$ range.
 

     
 
 

[Kiriakos-GR]

second wave

[Joshua]

I'm definitely no expert, but the build construct looks dodgy crap. Especially that one resistor and the way the LCD is attached around to the board.

[Kiriakos-GR]

Ok did lots of testing

I will just present the numbers so to make your own conclusions.

1)   DCV Test
On DC the DMM is almost fast and partially accurate and I had spotted a constant error that grows by raising the voltage.

Example: Agilent U1272A VS V&A 18B
1.003 --- 1.007
6.000 --- 6022
20.001 --- 20.05
30.000 --- 30.07
33.52 --- 33.60

Reference source 10.002  --- 10.025
The good part it does not overshoot.
Display update 2 per second.

2)   DCA Test.
The DMM are 6000 counts even so at uA it managed to show 6400uA before it gets out of range.
I had spotted again a constant error that grows by raising the uA current.
10uA --- 10uA
100uA --- 100uA
3000uA --- 3007uA
6000uA --- 6018uA
Display update 2 per second.


3)   The ACV Test
I tested it at measuring 220V Mains, it was spot on at 225V with the Agilent next to it.
Display update 1 per second.

4)   Ohms range.
I got very mixed feelings by it.
a) The relative functions needs 5-6 seconds to zero out !!
b) From 1-10 ohms the DMM needs four seconds to adjust it self,
I had use my resistor decade box, and from the setting of 1 Ohm to two,
The DMM needed 4-5 seconds to adjust it self and read 2 Ohms.
c) Above the 10 Ohms up to 900K , the DMM needs 1.5 - 3 seconds to read the value , and works a bit faster.
d) Accuracy acceptable, nothing major here.

5)   Capacitance. 
Probably the most problematic function on it.
Examples VS Time in seconds so to read them.
10uF  =  5 seconds.
100uF = 15 seconds
220uF = 30 seconds.
I can simply speculate that at the max of 330uF of it range it would need 45-50 seconds to read the capacitor.
At the Capacitance mode the manual range button does not work.

6)   General observations.
The back light on the LCD are only part that I liked on it.
It has an evenly spread white color, and it is bright enough.
The negative part is the manufacturing quality of the case of it,
It is so poor, that there is even small open gaps between the gray plastic and the yellow body, and escapes light from them, and also its an open door for the dust so to enter in the inner side of the display, and get trapped in there.

The plastic body of the unit is very slippery and light weight, no anti-slip elastic pads, it could easily slide from the bench and hit the floor, no matter if it is standing on the tilt bail or not.

The tilt bail is nothing special, and in this new DMM it is very hard to unlock it.
The battery compartment it is very narrow, so narrow that you need a screwdriver and to use some pressure so to get out the battery from it.

The four screws around the body, gets in tiny plastic threads, that easily can break apart, actually the one of those points break off when my own friend tried to open it up in his own shop, the screws was over tighten from the factory.

I am very disappointed from it.
I was expecting more from one unit that it was designed at 2006 – 2007.
The inner PCB problems, the external level of quality, the slow like turtle behavior, and the retail price at about 50$, makes this unit totally undesired for any advanced hobbyist or professional.
The over-voltage protection circuitry and the 600V Fuses, is a positive step and the  test leads are above the average, good cables and probes.
But the overall picture is tragic.

And speaking about pride, even as re-branded, there are no markings of V&A or Mastech on it, or in the operating manual.
But even so I will make you all famous, because you had made a such of garbage and shipped it on my own country.

[alm]

Thanks for doing the review! Pretty much matches my expectations from V&A, they seemed like cheap(ish) knock-offs to me. Likely designed and manufactured by someone else.

Funny how their dodgy LCD backlight constructions is similar to how it was recently discussed on this forum, guess the bodge job is cheaper than a proper backlit LCD.

My guess is that the 2006 award was awarded by Mastech/V&A.

[Kiriakos-GR]

Thanks Alm.

Personally I was hopping to was something promising as new product ( The promising pictures and hypes on their web site made me think that way).
 
The industry of DMM units, its not similar like the car industry that presents new models every one or two years.
I was hopping that they would had add some extra thought on it, like to was a new step for the future.

I would prefer 1000 times to was  20 or 40$ more expensive, and the actual product to was near or even better to the latest offerings of Uni-T.
I would prefer to not had this cheap(ish) IC bubble , and instead to had a true ESS-xxxx or AME-xxxx or  MSP-xxxx type, or similar IC. 

The ruggedness level is Zero, one large zero with the know big hole at the center of it.

And the most important, its not even dust proof, most of the 20 years old designs was respecting this factor,
this one does not.
And it did happen even to me,  after putting the rear cover on, and it was closed and clean,
I started testing it, and few minutes later I discovered particles of dust at the inner side, between the clear protective plastic and the LCD display.
I got totally surprised, because I had not remove the PCB from the case , and so it was not my fault. 
In order to remove this chunky particle of dust, I tried to blow some compressed air, from the openings ( escaping light picture),
and this action made the trick.

I was not even bothered to test the Data logging capabilities of it,
the specific model version comes with an IR-USB cable.
And in the accessories there is a set of short cables with banana & crocodiles ( capacitance measurements).

By just looking the accessories, you get some raised expectations, about this unit.

V&A haves around 10 similar models, based in the specific design with small changes between them.
And their top ones, if I can use this word, are one or two models at 10.000 counts, and one at 50.000 counts.

One product review of those, it would give plenty of information's , about what the V&A - Mastech had in their mind's by popping up this specific series.

If the VA18 are truly their bottom low line ( Price VS futures ), and if the 10.000 or 50.000 counts in not any better,
then its just a teddy bear line of products, just for kids with very low level of awareness.

Currently , and from all the reviews that I have see by Dave and others, if there is an award for the Chinese manufacturers,
goes exclusively to UNI-T,  because those products does not look good only as drawings, but they work in the real world too.
Even if they are not champions in speed.

About Mastech I am totally confused, they was a leading manufacturer before 20 years ago,
even today many companies copying their 20 years old product range.
If they are involved in the specific design, they should fire their product developers, or close down as company.
No one really needs such quality of products today.
   
 
   
 

[firewalker]

I have this DMM for about 2~3 years. I wanted something inexpensive with pc interface for a friend. In the end he didn't used it and gave it to me. The quality isn't good (good enough for 40 euros) but it is always spot on compared to very good DMMs. Ah, the probes are nice. Really soft.

I also wrote a C program for communication under GNU/Linux. As I can recall it was working but it wasn't a beautiful code example.

http://pastebin.com/T4YuSbhB

Alexander.

[firewalker]

Just took apart mine.

[74HC04]

OK - I'll bite. Here's my VA18B (yes, I know what the PCB says! I guess this is an early version). It was a present from my (now) ex-girlfriend who won it in a giveaway at a summer job in a calibration house. I haven't used the meter much yet and have had to replace the battery snap due to a leaking alkaline. The LEDs don't seem to bleed throughthe case with mine but one of the screws no longer has a thread in the plastic to bite into.

Irritatingly, the meter reads approximately 97 ohms when the probes are shorted. If anyone can work out which pots calibrate what, that'd be great but I'm not holding my breath here

Note the bodged piezo with 100R series resistor etc.

[Kiriakos-GR]

Thank you people, you pictures are additional proofs that my point stands.

I do not expect any reaction from V&A and Mastech about this subject.

The raised  awareness is my own payment, for the five hours that this presentation had cost to me.
No to say that I did lost my sleep because of it, due the fact that I took it at night,
and I had to return it in the beginning of the next working day. 

[ZTG]

Hi
I have the same multimeter (the name is different: MAXWELL MX-25328) but unfortunately burned down one resistor R33. Would somebody read me the value of this resistor? I could not read from the pictures because is just very closed to VR2 pot.
Thank you for any help-

[mAJORD]

wow, that's pretty crap all round, even if it is only ~$50 .

easy to be fooled by the exterior, it has a nice design and good finish.

thanks for the review!

[T4P]

Sure the HRC fuses are good news but it's generally crap .
UNI-T appears to make meters much better anyway ( I believe the 20 years history mastech cannot possibly be from china, i remembering seeing elsewhere that there is a original mastech from the states and one clone from china )

[Bored@Work]

When it comes to multimeters, there are

Mastech (aka Precision Mastech), which is the real one (mostly their meters are in green or black enclosures),

and

V&A, posing as Mastech on the internet (mostly their meters are yellow).

Both are from China.

Mastech in the US is a recruitment company, not dealing in multimeters.

[T4P]

When it comes to multimeters, there are

Mastech (aka Precision Mastech), which is the real one (mostly their meters are in green or black enclosures),

and

V&A, posing as Mastech on the internet (mostly their meters are yellow).

Both are from China.

Mastech in the US is a recruitment company, not dealing in multimeters.

OOPS ... i err ... the original mastech green and black cases mostly name their products with MS and then numbers ...

[Uwe Hermann]

I have a Mastech VA18B too, and did some more teardowns and research on it, as I plan to write software-support for this (and other) DMMs in sigrok (an open-source, cross-platform software suite for logic analyzers, oscilloscopes, dataloggers, multimeters, and other gear).

The current state of my infos (plus teardown photos) is available from:

  http://sigrok.org/wiki/Mastech_VA18B

The currently known devices that are rebranded VA18B's are: Amarad Hellas Electronic VA18B, Velleman DVM1200, Maxwell MX-25328, Peaktech P3375. If you know of any other names for this device, please let us know (only names where they have actually changed the logo / vendorname on the device; of course it's sold under its original name by many shops, too).

I'm attaching photos of a teardown of the USB interface cable I did, haven't seen anyone do a teardown of that one, yet. My cable has a Prolific PL2303HX USB-to-serial chip (yes, I accidentally ripped off one of the wires while opening it, but I soldered it back), though according to some other sites earlier versions used a Sunplus SPCP825 chip, apparently. If anyone has a teardown of the cable with SPCP825 chip, please post that here, I would be very interested in that. Thanks!

Also a little hint wrt PC logging, in case you were wondering: To enable output to the PC on the multimeter you have to keep the Hz/DUTY key pressed while powering on the device. However, it will auto-poweroff after roughly 1 hour, even in this mode. To avoid that, press both the Hz/DUTY and the SELECT key during power-up (see manual, page 9, section 2.3.1). Yes, it is documented in the manual if you read all of it very carefully, but it's not very obvious.

The serial data is sent out roughly every 300ms (I verified that using a logic analyzer), though every 9th chunk of data is 600ms apart from the last one, which is a bit strange.

Anyway, I might try to find out which chip (the one under the black blob) might be used on the DMM when I have some more time. It may be possible to determine the chip by figuring out (parts of) the pinout and/or comparing the serial protocol format to various DMM chip datasheets, see e.g.

  http://sigrok.org/wiki/Multimeter_comparison#Multimeter_ICs

Uwe.

[T4P]

@Uwe you better check the description, V&A is not a department of Mastech
It's Yihua V&A that is pretending to be mastech

[Uwe Hermann]

@Uwe you better check the description, V&A is not a department of Mastech
It's Yihua V&A that is pretending to be mastech

Hm, that's possible, the description on their site leaves room for interpretation. Is this a guess/assumption or do you have any official source for V&A not being related to MASTECH in any way? Have you asked either of the companies and did you receive a response? I posted a question via the p-mastech.com contact form, but no answer so far.

The V&A website does have "http://www.mastech.com.cn" as domain strangely, but that doesn't have to mean very much, of course. The MASTECH DMMs are all named MS* usually, and the V&A ones are not, but that doesn't have to mean anything either.

Uwe.

[T4P]

It's written elsewhere in this forum
https://www.eevblog.com/forum/product-reviews-photos-and-discussion/va520-another-low-cost-lcr-meter/msg89779/#msg89779

[Uwe Hermann]

It's written elsewhere in this forum
https://www.eevblog.com/forum/product-reviews-photos-and-discussion/va520-another-low-cost-lcr-meter/msg89779/#msg89779

Hm, that doesn't sound like any official information or conclusive proof either, though.

However, I have now received answers from both MASTECH (p-mastech.com) as well as V&A (mastech.com.cn), so here are the email logs for publically documenting this stuff, so that other people who are wondering about this can google it:

Question for MASTECH:

Hi, I've seen that a company named "SHANGHAI YIHUA V&A INSTRUMENT CO.,LTD" is referring to itself as "Mastech Shanghai" on their website:

  http://www.mastech.com.cn/html/en/about-us.htm

"SHANGHAI YIHUA V&A INSTRUMENT CO.,LTD, known as Mastech Shanghai, is one of the major test instrument manufacturers in China specialized in professional test and measurement instruments."

Their domain name also contains "mastech". Is this company really associated with MASTECH in any way, or are they only using the MASTECH name to draw attention or such?

Curious, Uwe.

Answer:

Dear Sir, We are MASTECH in Dongguan.  Please refer to as below: http://www.mastech.cn/.  Please don't hesitate to contact me if you have any questions.  Thanks & nice day, XXXXXX.

Next question for MASTECH:

Thanks! Just to make sure -- so that means that V&A (mastech.com.cn) is
not the same company as MASTECH (p-mastech.com or mastech.cn), correct?

And V&A has not been bought by MASTECH (or vice versa), and V&A is not a
subcompany of MASTECH, right?

Thanks for clarifying. Uwe.

Answer:

Dear Sir, MASTECH in Dongguan. V&A in SHANGHAI.  We didn't have any relationship.  We office in HK. & factory in Dongguan.  Thanks & nice day, XXXXXX.

Question for V&A:

Hi, I'm a software engineer who works on a software to read out measurement
values (over USB) of some of your multimeters, e.g. the VA18B.

I'd like to ask whether V&A (mastech.com.cn) and MASTECH (p-mastech.com)
are related to each other.

Is it the same company? Has one of them been acquired/bought by the
other? Is one of them a subcompany of the other? Any other relation
between the two?

Thank you very much in advance!

Cheers, Uwe.

Answer:

dear  Cheers;
Thank you very much for your email.
For V&A (mastech.com.cn) and MASTECH (p-mastech.com) ,we are the different company and we have nothing with them now.But   8  years before we had been the same company .Now we seperated from them .
Now our brand is v&a and website is : www.mastech.com.cn
Any question or details, kindly contact with me.
YYYYYY

There it is. The answers are kinda contradictory, but I think I'll just assume V&A was part of MASTECH at some point in the past.

This is also hinted at by some of the V&A DMMs being named MS* after all, e.g. the MS8201H being sold by V&A was also sold under the same name a few years earlier by MASTECH:

http://www.mastech.com.cn/html/en/products-ms8201.htm
http://www.multimeterwarehouse.com/MS8201Hf.htm
http://web.archive.org/web/20080913163002/http://www.p-mastech.com/products/04_dm/ms8201h.html

Anyway, they're certainly separate companies now, so I renamed the sigrok wiki article to:

  http://sigrok.org/wiki/V%26A_VA18B

Hope this clarified some parts of the situation at least.

Uwe.

[T4P]

Officially is : V&A is part of Yihua
Mastech IS Mastech, V&A claiming to have parted from Mastech is one of their lies
As they always pretended to be mastech
You can't trust the chinese you know.

[Uwe Hermann]

Officially is : V&A is part of Yihua

Well, sort of. According to http://www.mastech.com.cn/html/en/about-us.htm the company is named "SHANGHAI YIHUA V&A INSTRUMENT CO.,LTD", so V&A seems to just be the short form of the company name.

Mastech IS Mastech, V&A claiming to have parted from Mastech is one of their lies

Now, that is a pretty strong statement I would dare say. What proof can you show that this is indeed the case, and/or which sources did you cite here?

As they always pretended to be mastech

Same as above. What make you so sure that would be the case? Source?

You can't trust the chinese you know.

Um... ?!?

[T4P]

LOOK at china's history and you know what i'm getting at!
Copyright infringement ... even with their own brothers!

[felix_GR]

Thread necro, but i just registered to write this down, in case someone else is interested.

I own the same DMM, since i am not a pro and i didn't have much knowledge when i purchased, i am satisfied.

I managed to make the PC-Link work in Win7 64-bit with my SunPlus USB-to-Serial bridge cable. Two things needed :


1) Software-wise--> find the .exe of the PC-Link and change compatibility mode for Windows XP SP3 and administrator.


2) Driver-wise --> After a long search for Win7 compatible drivers ( Harware ID for the Sunplus is VID_04FC&PID_0201, so i searched a bit ) i managed to
   
    find a heart rate monitor for sports, that probably uses the same device. Traxmeet is the site, >this< is

    the page that has the link for download  direct download >here<.

    Traxmeet HR Sync is the software that includes Sunplus SPCP825K USB-to-Serial COM Port Driver v1.0.9.0, dated 1/7/10.

    After installation, you can manually uninstall the HR Sync program, the needed driver stays unchanged.

    When done , find the Sunplus device in Device manager and change the Communication Rate to 2400, and select the same port Number in PC-Link software in order to work.


Alternatively, i've saved the relevant files from the Windows Driver folder in a .zip and uploaded it  >here< , in case someone wants to install it manually without the HR Sync software.



That's all, hope i help someone.

[Nebukad]

@74HC04:
If you're still curious to know or if someone else stumbles upon this thread and wants to know: I managed to figure out, how to calibrate this thing:

VR1: Temperature (coarse)
VR2: Temperature (fine)
VR3: Capacitance
VR4: AC-Volts
VR5: DC-Volts

After setting up these pots, the meter gives more or less accurate readings - at least within spec. But I still don't like this thing after seeing the inside.