Mastech MY68 multimeter

[Hydrawerk]

Do you have any opinion on Mastech / Sinometer MY68? It probably used to be a popular autoranging multimeter back in 1990s. It is still sold. http://www.amazon.com/Sinometer-MY68-Autorange-Digital-Multimeter/dp/B000J40T3U
Some of the units have bar graph, while others do not. There is probably only a little input protection. Maybe it was added in newer units.

[Hydrawerk]

Some teardown photos were found here. http://www.ebastlirna.cz/modules.php?name=Forums&file=viewtopic&t=46678
Photos made by 100upa and CZJKP1. The schematic looks like it was hand-drawn.

[wraper]

Mastech is original one. Others are clones even crappier than mastech. It's okayish meter for the price (have seen for EUR 14 here, hmm, no those were Lats which we no longer have, so about EUR 20), basically next step after M890 series. Hardware has gone thru many iterations and current MY-68 from mastech is very different inside compared to 90's or 2000's MY-68.

[wraper]

Some teardown photos were found here. http://www.ebastlirna.cz/modules.php?name=Forums&file=viewtopic&t=46678

Looks like one I had in 2000's

[Hydrawerk]

Another unit. Design looks like early 1990s.

[Hydrawerk]

More pics.

[Hydrawerk]

current MY-68 from mastech is very different inside compared to 90's or 2000's MY-68.

Mastech seems not to produce MY68 nowadays. http://www.p-mastech.com/product/category/79

[wraper]

current MY-68 from mastech is very different inside compared to 90's or 2000's MY-68.

Mastech seems not to produce MY68 nowadays. http://www.p-mastech.com/product/category/79

They were available 2 years ago. Probably they phased them out recently.

[Hydrawerk]

This looks like a new design of the PCB. http://ru.aliexpress.com/item/MASTECH-MY68-Electronic-measuring-instrument-handheld-multimeter-3-3-4-LCD-3999-Counts-Auto-Ranging-AC/32346197324.html

[wraper]

Dunno if this is genuine Mastech. At least old revision had 3260 counts and had a bargraph. All those sold under Mastech name on Aliexpress claim 3999 counts, and don't have a bargraph. That on the picture in that aliexperss listing is old revision, I know for sure newer ones had one additional dial position.

[Mkrtich]

Forgive me if I have duplicated this REPLY - my first posting . Having trouble with uploading photos. Will send text only to see if it gets through and will try sending photos separately if successful.

 Hello - I recently acquired a used Kincrome K8014 in Australia for $45 from Gumtree which actually is the Sinometer Mastech MY68. Bursons sell them new for $99.00. https://www.kincrome.com.au/pro-digital-multimeter-k8014#

Not knowing much about multimeters, I didn't realise it was faulty until I took it apart - weak piezo buzzer, slow start up time, faint display at times and both fuses blown, but started to get rudimentary education by watching David Jones and Martin Lorton You Tube video sessions - both guys I very much admire for their unique ability to communicate complex topics with great ease and entertainment. It was due to their knowledge that I became intrigued about what a marvel these multimeters are inside.

I eventually found what I call a loose tooth component (X-TAL Crystal Oscillator - schematic diagram also found on Google) that had no solder on one leg holding it to the PCB and accidently fixed all three problems it by soldering it on the board (my first use of a soldering iron but now more knowledgeable about soldering after watching David Jones's three video sessions on soldering) and cleaning off the white powder crystals on many solder pins on the underside with isopropyl alcohol. The 11 position multifunction dial has some marginal problems locating the correct reading for the function you require, but if you tweak it by a marginal half a mm movement the display shows the correct measuring unit and sits where it should - I have taken the function dial apart and cleaned the internal circular tracks a few times but made no difference. I know its peculiarities now and am comfortable with it. I have used it as my learning tool for multimeters education and maintenance. I am not a serious user of it just household tasks of battery tests and occasional power supply tests. The leads although not silicone are good and rated at 1000v CAT III - protected with plastic covers at both the meter connector and test lead point ends.

It is marketed by Kincrome as a Professional Series - and yes, it is OK to use - IEC 1010 rating, but not in the class of a Fluke or even the Brymen BM 257 or BM235 which I think are superior in technical design and construction. The MY68 is good for general use around the home and designed to their price point. I use my Fluke 77 Series 1, circa 1984 as a benchmark - although older than the Mastech  MY 68, it has the appeal of its original design simplicity. The Mastech MY 68 uses surface mounted technology, so I would say that it is still being manufactured by Sinometer - here is their web site link http://www.sinometer.com/?Digital-Multimeters-DMMs-category171-------12-sort-asc--4.html - it is the Mastech MY68N. This company also makes the UNI-T Range and the ever promoted, under $10.00,  DT830 series of multimeters and a whole lot of other well known labels. 

Now that I am more educated on multimeters, I would not buy the MY68 for $100 new, I would prefer to spend the additional $50 and get the EEVBlog Brymen 235 - well done Dave!

Here are some of my photos. Hope this may be interest to you both.

regards
Nik

[Mkrtich]

Discovered why photos were not being uploaded - raw file size too big - emailed photos to self from Photo Gallery - reduced each file size from 1.22Mb to under 160kb which now should upload hopefully. Having trouble with photo of screen display - if you look at the Kincrome link, it shows the second photo shows display with the bar graph. The display is very clear but not backlit. Specifications can be downloaded from the Kincrome User Guide - states 3260 counts MAX and updates 2-3/sec with DC Voltage Accuracy Range of +/- 0.3 to 0.5 % +/- 2 digit. Accuracy statistics for other functions are not as generous.

regards
Nik

[Mkrtich]

This is the screen display turned ON.

[Mkrtich]

Better resolution photo of the Kincrome K8014 PCB

[Hydrawerk]

Looks like a redesign with the same circuit, but with SMDs used.

[Mkrtich]

I now understand another peculiarity of this DMM. The Kincrome MY68 that I own looks like what Kincrome chose to bring into Australia at the time of original purchase by the previous owner - it has a 3260 count display. The Sinometer MY68N which appears to be sold in the USA, Europe, Middle East and Russia, which makes me think it is a more advanced or current model perhaps, is a 3 and 3/4 digit display with a 3999 count, so slight marginal difference in technical specifications. Specifications for MY68N attached and User Guide for Kincrome K8014 in separate post due to file size.

[Mkrtich]

Here is the link to the Kincrome K8014 webpage. https://www.kincrome.com.au/pro-digital-multimeter-k8014 The User Manual  is shown under the description. 

[Mkrtich]

In case anyone else has similar issues with the positioning accuracy of the function switch selector on the Mastech MY68/Kincrome K8014 for

" the 11 position multifunction dial has some marginal problems locating the correct reading for the function you require, but if you tweak it by a marginal half a mm movement the display shows the correct measuring unit and sits where it should - I have taken the function dial apart and cleaned the internal circular tracks a few times but made no difference."

I had a Eureka moment this morning and decided to experiment with the following fix. The plastic dial which holds the copper springs that rotate around the PCB circular tracks which define the function you select have three plastic lugs that push through the PCB and pop over the PCB edge for locking onto the PCB - one of these looked slightly deformed and therefore provided less connection strength to the half moon shaped brass spindle that is moved by the external dial. Given that a replacement wheel was not a realistic solution for me, I decided to get 100mm of white plumbing thread seal tape and wrapped this around the spindle making is marginally larger. This now gives the function dial motion a firmer movement with no variation, once a function is selected, there is no movement now - all measuring function positions align perfectly and show the correct measuring unit. Hoping it will be a long term fix. 

[AleDanie]

I have a MY-68 Multimeter but not is the same circuit,the mine uses Microprocessor FS 9922 DMM3,¿what is your opinion about this IC?,this is a A/D conversor of 4000 counts with Microprocessor.

[AleDanie]

That is exactly my DMM in a review with a Fluke 87V:
 

It`s a very good Multimeter I have it for more of 4 years and I haven`t any problem,I am a Electronic Technician and works in reparation of Color Tv,LED,LCD,Plasm,Audio,Dvd,Blu-Ray,PC,Video Games,Micro wave owens,etc.
 

[chirality]

Hi all,

I have a Mastech MY68 too. Actually branded Circuit Specialists but it's marked MY68 in the corner.

I understand that a current clamp can be used with it -- at least the manual mentions it as an optional accessory. Does anyone know which clamp model # is supposed to pair with it? I found this one, MS3302, but I don't know if it works: 

https://www.banggood.com/MASTECH-MS3302-AC-Current-0_1A-400A-Clamp-Meter-Transducer-p-911438.html?cur_warehouse=CN

Edit: There's also an MS3300 that looks slightly different: http://www.mastech-group.com/products.php?cate=95&PNo=224#_

Edit2: Appears that the MS3302 measures AC current only at two sensitivities, 1mV ~ 1A and 1mV ~0.1A  MS3300 does AC and DC current measurements but only at 1mV ~ 1A