Fake VC830L digital multimeter
This article is intended to explain some bad things about cheap
digital multimeters since these devices are available in large quantities in
Serbia. The key point of this article is security since cheap digital
multimeters are not tested/produced according to standards.
VC830L is one digital multimeter available in electronics
distribution stores in Serbia, but we will avoid company names, since this
article is more about “pay attention before you buy” cheap digital multimeter. The
VC830L is about 10 euros, you cannot expect too much, but if you are not able
to buy professional digital multimeter which costs over 100 euros, you will
certainly buy the cheap one.
Front mask: VC830L digital multimeter. |
The part interested for us is security so let see what we actually
have regarding VC830L digital multimeter. It has three input connectors,
starting from the left side: we have connector for 10 amps, common connector (COM)
and the right one intended for voltage, resistance and miliamps measurement. That
is all good, it doesn’t have a fourth input to provide more secure measurement by
separating miliamps to additional input channel, but we can live without that. What
we can see from the figure #1, it is clearly marked that all measurement inputs
are protected by fuses. There are two fuses, one between 10 amps input and COM
and second one between COM and voltage/resistance/miliamps input. And that is
very good, it is a good protection. But, do not believe in
these labels until you check is it really secured by two fuses.
Figure#1: VC830L inputs, left: 10 amps, middle: COM and right: miliamps, voltage and resistance input. |
When you do open VC830L (figure #2) you will see that there are no fuses
inside, more badly there is soldering place intended only for one fuse, and if
you want that fuse, that means that you have to spend more money, buy required
fuse (in this case 0.2 amps) and do manual fuse assembling (soldering). Who
really wants to do that? It is not a problem to spend more money and do some
soldering, but I’m expecting that digital multimeter VC830L is protected with
two fuses as it is clearly marked on the front of the digital multimeter
(figure #1). This is very bad, at the front mask it is clearly marked
that protection does exist between inputs, but when you do open digital
multimeter you will not find any fuse at all.
Figure #2: Soldering place for one fuse only, and it is intended for 0.2 amps fuse protection. Look under red rectangle. |
Question: where is the second fuse, fuse related to 10 amps input?
There is no second fuse! It is completely skipped, removed from the design or? Ok, it looks that VC830L is not actually
VC830L by initial design since original digital multimeter VC830L is designed with
two fuses, isn't that right? Yes, it is, that is a good question about electrical
circuit and which digital multimeter is actually packed inside VC830L case.
One is sure, this is not a VC830L digital multimeter! It is only the
VC830L case and that is even more badly. Also, it is not possible to find any of
the labels printed on the PCB and it is not possible to find additional
information. The conclusion is simple: distributors sell VC830L digital
multimeter as VC830L digital multimeter, but it is not VC830L digital
multimeter inside!
It is not possible to find additional printed labels on the PCB about electrical design version or revision. |
Anyway, this article is not about distributors from Serbia and Hungary,
since the main supplier of these digital multimeters comes from
Hungary to Serbia with China origin, but we can only say that this is very bad situation
and it could be very dangerous since digital multimeter is labeled with CAT II
and that means that we are able to do measurements of 220V 50Hz as it is AC
standard in Serbia. It is very important to “pay attention before you buy”! But,
how to check digital multimeter against fuses? We can ask a seller is it possible to open the complete multimeter
case if there is no additional place for the fuses like there is a place for the
battery pack. If there is an additional place for the fuses, that case is simple, just ask the seller to open the additional case and you will see the
fuses or not.
The question is: does all cheap digital multimeters includes additional place dedicated for the fuses as for the battery pack? The answer is NO, so ask the seller to open the complete multimeter case if it is possible. If it is not possible, the only way to check fuses before you buy the multimeter, is to search Google and find some articles about multimeter, or ask someone for help. Otherwise, you will never be sure what you are actually buying.
The question is: does all cheap digital multimeters includes additional place dedicated for the fuses as for the battery pack? The answer is NO, so ask the seller to open the complete multimeter case if it is possible. If it is not possible, the only way to check fuses before you buy the multimeter, is to search Google and find some articles about multimeter, or ask someone for help. Otherwise, you will never be sure what you are actually buying.
There is only battery pack place, there is no separated place intended for fuses. The only way to check does fuses are included is to open complete digital multimeter pack. |
At the end, pay attention, figure #3, digital multimeter is
not assembled completely, there are some soldering places intended for diodes
which are missing, which lead us to the additional input protection problem,
since the diode bridge is used to protect input circuit against high currents before fuse
actually start to react. That is also bad for us, but not for the people/services
who actually do assembling of these digital multimeters, so it is not bad to
check existence of the diode bridge since it is an additional input protection.
Figure #3: diode bridge is not assembled, another protection issue. Look under red rectangle. |
Poor soldering quality. It looks that this digital multimeter was not tested against soldering quality after it is assembled. But anyway, this is hand-soldering work and it is very poor in quality.
Related articles:
SERPENT I - DC motor controller SERPENT I - PCB DIY (do it yourself) assembling - video clips examples How to design LM324 Astable Multivibrator How to build do it yourself printed circuit board (DIY PCB) by using thermal transfer method Programmable autonomous vehicles – Fundamentals, Part I Power switch as current amplifier How to design voltage reference by limiting current consumption
zilsel-invent assumes no responsibility or liability for any errors or inaccuracies that may appear in the present document. Specification and information contained in the present schematics are subject to change at any time without notice.
|
You have a picture of the roulette behind
ReplyDeleteI was looking for an advanced digital multimeter on the internet, but I did not find anything that can satisfy my specifications. Your blog has helped me to buy my desired digital multimeter without any hassle. Omni Controls is the only place that is offering digital multimeters at the best price. My digital multimeter has everything that an advanced multimeter should have. My Digital multimeter also includes a built-in thermometer and temperature probe. Omni Controls is the only organization that has the largest collection of Digital multimeters in their inventory. Moreover, the prices are very affordable over here. You deserve big thumbs up.
ReplyDeleteBogus advertising..
DeleteGreat content.Thanks for sharing this fruitful content.
ReplyDeleteBuy Online digital multimeter in India.
Awesome Content. I think Fluke is one of the Top and best company which produces Digital Multimeter in the market. It shows almost an accurate reading and it is very easy to use.
ReplyDeletebest article i have ever read multimeter price in pakistan!
ReplyDeleteThanks for sharing the such information with us.
ReplyDeleteMultimeters
Great Article!
ReplyDeleteThankx for sharing
multimeter price in pakistan
if you are working on an electronics or electrical project then you must need a multimeter to check the current and voltage from time to time to complete your task. so for this purpose, we reviewed different Digital multimeters brand and multimeters types to pick one of the best with high quality
ReplyDeletefor more information
Best Multimeter for electronics
Fluke tools for sale is really fascinating. I really want one.
ReplyDeleteGreat Article....If you like multimeters
ReplyDeleteCheck out www.keepontesting.com
You did an excellent job on this post!
ReplyDeleteIn this article, you will learn how to make a rechargeable digital multi-meter from PVC pipe sheets at home. We will use PVC pipes sheets to make a multi-meter box. You can easily make a digital multi-meter at home in simple steps.
how can we know if the multimeter is legit? aside from buying it from the store?
ReplyDeleteGreat Article....If you like multimeters
ReplyDeleteCheck out www.bloomenterprises.com
Great content.
ReplyDeleteThanks
Awesome post.
ReplyDeleteThanks
Muy interesante tu contenido... Al final de todo te das cuenta que los productos chinos te ofrecen un poco de cosas, pero en este caso es más delicado, pones tu vida en riesgo al confiar en un aparato que supuestamente tiene protecciones y es Mentira 🤔 Preocupante de verdad
ReplyDelete