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A quick spiel: Dangerous unfused MAS830 multimeter clones and how to add fuses in easily

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JLNY

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(EDIT: the original title was: "A quick spiel: Dangerous unfused '830' multimeters and how to add fuses in easily", but it appears that most of these generic multimeters with "830" in the model are clones of the Mastech MAS830)

Hello all,

I was recently looking into finding a compact multimeter with a continuity buzzer to use for "away" jobs where I need to debug hardware but don't want to bring out my nicer and somewhat bulkier meter. Looking around online, I was able to find many listings for variants of an ultra-cheap "830" model multimeter, which in some cases can be had for as little as $3 including shipping. At such a low price, I brought two different ones-- an 830D and an 830L (with a backlit LCD), and decided to see which one I liked better. The listing also mentioned that it had a replaceable fuse for the lower current range, which is actually not always the case on these ultra-budget meters.

...Well, it turns out that last part of their description-- for both meters-- was a total lie. can you spot what's missing on the back of that board?
IMG_9135.jpg

As it turns out, cheekily hidden underneath the piezo buzzer for the continuity test were the pads for the fuse holder, unpopulated and actually shorted out with a trace on the board (EDIT: it seems that the thin portion of the trace was meant to act as a fusible trace, but it is dubious at best that this would allow for an accurate fusing current, and would obviously not be replaceable. Credit to djsfantasi and Tony Stewart for this insight).
IMG_9144.jpg

So, I took an exacto knife, scraped off the solder mask on the trace, made horizontal cuts across it down its entire length, then used a hot soldering iron to chip the trace up off the board. (The heat of the soldering iron works really well at de-laminating the trace off the PCB)
IMG_9154.jpg

Finally, I added a bit of solder to the pads and tacked down a pair of fuse holder clips
IMG_9155.jpg

IMG_9157.jpg

Hopefully now I can feel a little better about bring this meter with me. If it weren't for this critical component they decided to leave out, these would otherwise be decent meters. The 10A range is still unfused aside from that piece of wire, but that isn't as unusual, and I could add a fuse to that too if needed.

IMG_9163.jpg

Overall, I was disappointed but not exactly surprised to see that they had left out the fuse. Fortunately, they had the courtesy to leave the pads in so I could fix the issue. Even so, they are still pocket-sized, reasonably usable meters for what they are, and I won't feel too bad if I blow one up by accident.
 
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djsfantasi

Member
Note the trace shorting out the two pads. It is made of two segments of different widths. One segment is quite narrow. That is your fuse. I have seen this technique on several different boards.
 

JLNY

Active Member
Note the trace shorting out the two pads. It is made of two segments of different widths. One segment is quite narrow. That is your fuse. I have seen this technique on several different boards.
Interesting. I did notice that thin portion on the trace, but I would still massively prefer a proper replaceable fuse given that they specifically advertised it as such. Even for such a tiny trace, though, I would think that the fusing current would be higher than the intended 250mA.

It should be noted that the DT-830D (the black meter in the first image) had a slightly different board inside, where the "fuse" trace was half-hidden through a via connection to the other side of the board, so I don't know if it had that thinner portion or not. I did a quick test with that one where I tried overloading it very briefly; it was able to pull 1A no problem, and one of the chip resistors started smoking, so I don't think that trace is really an effective substitute for a fuse.
 

tcmtech

Banned
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And you expected what level of design quality and honesty from a sub $3 multimeter and its manufacturer? o_O :rolleyes:

Also I have no clue what the significance of '830' relates to in multimeter design.

It has 8 functions of which 3 are useful and 0 accuray in its ratings? :facepalm:
 

JLNY

Active Member
And you expected what level of design quality and honesty from a sub $3 multimeter and its manufacturer? o_O :rolleyes:

Also I have no clue what the significance of '830' relates to in multimeter design.

It has 8 functions of which 3 are useful and 0 accuray in its ratings? :facepalm:
LOL, The "830" refers to the model number, of which there seem to be dozens of similar variants following the naming format XX-830X. For example, the two I got were DT-830D and A830L. It's not clear whether this is some kind of generic designation used by multiple manufacturers knocking off some name-brand multimeter with that number in the name, or just one manufacturer making different variants with slightly different case styles. Some variants have back-lighting on the LCD, others either with or without the continuity buzzer, etc. but overall seem to have roughly the same capabilities.

The ratings, as per the listing (whether one chooses to believe these is another matter):
DC Voltage Measuring Range : 200mV-1000V, Accuracy Level : ±(1.0%+2dgt)
AC Voltage Measuring Range : 200V-750V, Accuracy Level : ±(2.0%+10dgt)
DC Current Measuring Range : 200μA-200mA, Accuracy Level : ±(1.5%+2dgt)
Resistance Measuring Range : 200Ω-2000KΩ, Accuracy Level : ±(1.2%+2dgt)
After a couple quick tests (measuring a couple resistors and reading DC voltages off of a power supply), it seems to measure within about 1-2% of my Fluke. I was honestly expecting worse, and I've still got my expensive meter for when I need accuracy.

...
Overall, I was disappointed but not exactly surprised to see that they had left out the fuse. ...I won't feel too bad if I blow one up by accident.
Quite frankly, one doesn't exactly need a high-quality multimeter to measure whether a power supply has voltage at the output, whether a resistor is 1k or 10k, or whether two points on a board have continuity.:p The only part of these meters I definitively do not like is the hFE tester-- the socket is horrible and you have to press it down far too hard in order to get a reading.
 
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tcmtech

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it seems to measure within about 1-2% of my Fluke. I was honestly expecting worse, and I've still got my expensive meter for when I need accuracy.
LOL. Fluke accuracy. :rolleyes:
Fluke hasn't made a decent multimeter in 30+ years and has been riding on what their name once stood for for just as long. :oops:

Heck most of their stuff is made in China now to the same specs most mid and decent grade chinese multimeters are made to that cost 1/10th or less as much. :facepalm:
 

nsaspook

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LOL. Fluke accuracy. :rolleyes:
Fluke hasn't made a decent multimeter in 30+ years and has been riding on what their name once stood for for just as long. :oops:
The top end field meters like the Fluke 289 made in the USA meter are still great. It's the only thing I buy for new techs for official ISO logged electronic machine maintenance with the Fluke 87 for general electrical maintenance.
 

tcmtech

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The top end field meters like the Fluke 289 made in the USA meter are still great. It's the only thing I buy for new techs for official ISO logged electronic machine maintenance with the Fluke 87 for general electrical maintenance.
Nope. Most of those are imported now too. Even Amazon admits to it right in their listings. :(

https://www.amazon.com/Fluke-289-FV...UTF8&qid=1472852944&sr=8-1&keywords=fluke+289

I'm assuming your techs aren't standard issue wire jockeys and the actually do know how and when to use the functions than the 289 series have? o_O

The thing is when you compare the prices Vs what they actually can do flukes top of the line meters liek the 289 are only fractions of percent better on paper specs rating and have and way less features than a good Chinese unit.

http://www.testequipmentdepot.com/fluke/pdf/289.pdf
http://www.myflukestore.com/product...MPWR1RAxPGLY8Z3Ge7_5-BsPBnK4YSDaVwaAsZR8P8HAQ
$600 - $648

Vs

http://www.dx.com/p/mastech-ms8218-...wQscUSCPbb3kA0AUsnXdsaApqK8P8HAQ#.V8n1NVsrKM8

$154.28

Sorry, but a few years ago I worked at a local retailer that sold both brands, to be honest, we saw ways less of the Mastech units regardless of their model come back for warranty than we did the flukes given percentages for numbers sold.
Heck or sales guys even pointed that out to customers and we played with them in head to head testing in our shops and couldn't find a problem with the Mastech meters that we sold for fractions of the price.
To be honest the Mastech units #1 selling points where that in fact they did everything and more than the fluke meters with near identical specs and accuracy ratings than needed for typical service work and cost a fraction as much. Plus if a guy lost one, got it stolen of just beat one up to the point he killed it he didn't get chewed out for it either.

When I started there my boss gave me choice of any meter we carried and I took the $20 Mastech over the choice of any fluke up to $500 our cost. It did more for insanely less cost and I wouldn't get chewed out for losing or wrecking it either. :p

Maybe your guys are doing some sort of specialty work but if not you're wasting your company and customers money and related paperwork trails on overpriced junk just to flash a name around. :facepalm:
 

JLNY

Active Member
$3 including shipping?
Wow.
The cardboard box where it is packed must cost more than the meter itself.
Probably not far from it haha. :D
For the life of me, sometimes I can't fathom how these Chinese sellers are making any profit at all when they have to ship a sub-$3 item halfway around the world to get it to me. Heck, even without the shipping, the idea that they can design and manufacture a board, populate it, put a custom COB controller on it, then assemble it in a case with an LCD and a pair of cheap probes, all for less than $3 per unit, just seems ludicrous to me.
 

nsaspook

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I'm assuming your techs aren't standard issue wire jockeys and the actually do know how and when to use the functions than the 289 series have? o_O

Maybe your guys are doing some sort of specialty work but if not you're wasting your company and customers money and related paperwork trails on overpriced junk just to flash a name around. :facepalm:
The primary reason is safety with long term calibration result reliability being second. I just donated some older Fluke 2x and 7x series meters to the local JC because of recent updates in local industrial safety requirements. I would use a Fluke 77 in a usec for anything at home because I don't have a need for CAT III 1000 V/CAT IV 600 V for the source side of the circuit breaker box and in industrial settings where we have power levels inputs post breaker in the 100,000 VA range and individual electronic circuit power levels in the 10,000 W level. One meter explosion that resulted in injury would cost more than any possible saving from a 100 $20 meters vs $700 units and most people here like their hands and fingers. Now, I have been looking at the Brymen BM869S meters for expendable electrician meters. :)

http://content.fluke.com/promotions...dmm/fluke_dmm-chfr/files/safetyguidelines.pdf
Where safety is a concern, choosing a multimeter is like choosing a motorcycle helmet—if you have a “ten dollar” head, choose a “ten dollar” helmet. If you value your head, get a safe helmet. The hazards of motorcycle riding are obvious, but what’s the issue with multimeters? As long as you choose a multimeter with a high enough voltage rating, aren’t you safe? Voltage is voltage, isn’t it?
 
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tcmtech

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Again I don't even buy the safety reasoning for buying fluke anymore being CAT IV rated and certified meters can be had for fractions of the way the flukes meters cost.

http://www.tomtop.com/digital-multi...nLqAvCScoH_699CJQAj_spcvAAIOHFsGIYaAtt88P8HAQ

Mastech 600 volt CAT IV rated $26.59.:rolleyes:

Or a CAT IV data logger with computer interface for multi operation data logging.
http://www.dx.com/p/mastech-ms8250c...l-multimeter-green-1-x-9v-6f22-148573#reviews
$55.15:rolleyes:

If fluke had a reputation for outstanding service and standing behind their products on warranty I would say maybe they are worth it for that but everyone who has ever dealt with fluke on a repair or warranty issue has said fluke they are about the worst there is for service and support behind their products. It's common knowledge that is easily confirmed. :mad:

At the business I worked at we hated dealing with fluke corp on warranty and service issues. They were all around dicks with terrible service.
If your fluke meter broke under warranty we couldn't just give you a new one and send the damaged one back for reimbursement of a new one. We had to send your meter in to be looked at (we paid shipping of course) and they determined what would be done which typically took weeks to accomplish and then most often paid the shipping to get it back too. :mad::mad:
whereas with the Mastech line we carried , no problem, here's a brand new one off the shelf and we take your broken one and send it back to the manufacturer free of charge or toss it in the garbage for you if the Mastech service department people said to. :cool:

Simply put, I don't know what's the appeal behind fluke is any more being there are countless other brands of meters that have equal to to better specs, safety ratings and certifications, warranties, more functions and far better customer support all for fractions of the cost. :(

Saddly I honestly consider them to be little more than a grossly over rated has been company riding on their name and the fact that the majority of their customers are near clueless to what's on the market to compete with them now.
 

nsaspook

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Saddly I honestly consider them to be little more than a grossly over rated has been company riding on their name and the fact that the majority of their customers are near clueless to what's on the market to compete with them now.
I respect your opinion but I specify in detail (for ISO audit trails on critical life-safety manufacturing) and buy equipment for professional 24/7 use and I've never and I mean never had a problem with Fluke quality or service. Maybe I'm just lucky.:angelic:
 

JLNY

Active Member
All,
After a bit of digging, I seem to have confirmed my theory as to why all these cheap multimeters have "830" in the model number: apparantly Mastech sells a compact, lower-end meter called the MAS830. Like the generics, there is also a MAS830L option with a backlight.

http://www.p-mastech.com/product/detail/324

http://www.p-mastech.com/product/detail/326

EDIT: now knowing this, perhaps I should edit my title and original post to refer to them as "dangerous unfused MAS830 clones" or something?
 

JimB

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OK, but do you know if the Mastech MAS830 has a "real" fuse, rather than just a skinny circuit board trace ?

JimB
 

tcmtech

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OK, but do you know if the Mastech MAS830 has a "real" fuse, rather than just a skinny circuit board trace ?

JimB
Pretty sure they do. I've had a few of their models apart before , even the low end bare basic ones, and they always gave me the impression they were well thought out and designed and they always had fuses.

Apparently their good enough designs to be mass copied and cheapened up now if their 830 model is what's being copied into every other cheapo brands 830's ! :p
 

tcmtech

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I respect your opinion but I specify in detail (for ISO audit trails on critical life-safety manufacturing) and buy equipment for professional 24/7 use and I've never and I mean never had a problem with Fluke quality or service. Maybe I'm just lucky.:angelic:
They probably know you have solid paperwork trails and can lawyer up if needed that's why they play nice with you. :p
For the average user or retailer that's generally not a option so they don't feel the need to respect them like you. :(

FWIW I have been reading up on threads and related information on fluke and their overall customer service and by far they have some pretty consistently bad ratings now for most of the reason I mentioned like the charingien for postage to and from and excessive wait times before they either honor their lifetime warranty or not and if not sticking a guy with a bill for repairs nearly equal to the cost of buying a whole new meter and worse. Apparently the little guy is not their favorite customer by any means. :(

BTW, what's up with their videos on how they design and test their own stuff? I see almost all their gear is made by other brands? o_O
To me that's like seeing a Ford service and dealership where all the company vehicles and shop machines are made by Chevy. Or going on a tour of a John Deere factory and seeing all their assembly line equipment and tooling is made by Case/IH. :confused: :facepalm:
 

JLNY

Active Member
OK, but do you know if the Mastech MAS830 has a "real" fuse, rather than just a skinny circuit board trace ?

JimB
I found this video of the inside of the MAS830. It's in Spanish, but it clearly shows fuses for both the low current and 10A ranges.


I was bit intrigued to see a ceramic fuse being used for the low current range, but a bit of googling indicates that they are likely "high rupture current" (HRC) fuses, which won't shatter explosively even if they get massively overloaded.
 

JimB

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