Mastech MS8050 Digital Bench Multimeter - Page 1
Forum section: electronics / testgear

author: pascal_sweden
author_rank: Super Contributor
timestamp: January 08, 2017, 09:43:14 pm
content: I found this nice looking digital bench multimeter on Aliexpress:https://www.aliexpress.com/store/product/MASTECH-MS8050-Professional-Desktop-Digital-Multimeter-Auto-Range-Bench-Top-Multimeter-High-Accuracy-True-RMS-RS232C/1181986_2043897747.htmlDid not find any comments about this digital bench multimeter on the EEVBlog forum, except for the following comment:https://www.eevblog.com/forum/testgear/uni-t-utd2102cel-vs-rigol-ds1102e/msg17920/#msg17920Could this remark just be a one time-bad luck issue? Or do all Mastech multimeters have quality issues?Any other forum user out here with a Mastech MS8050, who is willing to share how good the unit performs, and possibly also take apart the unit to check the PCB quality?I think that this digital bench multimeter is looking very nice!Below are the specs. Is this in line with Rigol and Siglent DMMs?http://www.p-mastech.com/product/detail/459

author: enut11
author_rank: Super Contributor
timestamp: January 10, 2017, 12:49:48 am
content: Hi pascal_swedenI do not own a Mastech MS8050 but I have had an MS8040 since June 2016.https://www.eevblog.com/forum/testgear/mastech-ms8040-true-rms-dmm-teardown/msg953583/#msg953583My unit has good accuracy, has performed well on all ranges and lived up to my expectations for a GP bench meter. I also have a Mastech MS8211 Pen Meter which also performs as intended.Based on my experience so far I would not hesitate to recommend Mastech DMMs as good value for money.enut11

author: klunkerbus
author_rank: Unknown
timestamp: January 10, 2017, 01:30:26 am
content: I've been quite happy with the used RSR rebranded version of the MS8050 that I grabbed on eBay a year ago for <$100 USD. My only gripes are I could do without the green case wrap, and what's with all four banana jacks being red color? Label on the back of my RSR unit is purple! (EDIT: Oops, I see the one in your link is purple, too). What was some product designer thinking?Hmm. Pulled the unit apart to look at the quality. I'd say mixed results on my main board, artwork dated 2006. I don't see any solder splashes as mentioned in the other thread, but yeah, there are some interesting SMD component installations. I see four capacitors that are formed from more than one part. One appears to be two capacitor chips in parallel. Two are formed from three chips in parallel. One, possibly the same as the pyramid one mentioned in the other thread, is three SMD chips soldered in a semicircle and the semicircle then soldered in parallel with another cap on the board. There's flux remaining on these areas, so it might be part of final tweak adjustments in manufacture or due to a recalibration.I'll see if I can get a pic taken for another post.

author: klunkerbus
author_rank: Unknown
timestamp: January 10, 2017, 01:46:12 am
content: Here's a pic showing the capacitors formed from more than one component. I see a few other areas where the SMD parts maybe weren't aligned all that well, but all in all I'm not sure I'm complaining about what I see.

author: pascal_sweden
author_rank: Super Contributor
timestamp: January 10, 2017, 02:29:07 am
content: Why didn't they solve this through 3 additional SMD footprints in series on the PCB board which are in parallel with the existing SMD footprint?I have never seen anything like this. Unbelievable!Hopefully this was a temporary workaround and has been addressed in the mean time through a new PCB revision. Maybe I will try to contact the manufacturer to verify this, if I get hold of their contact details.BTW: The orange capacitor doesn't look too well either

author: Lightages
author_rank: Unknown
timestamp: January 10, 2017, 02:51:55 am
content: The three capacitors in series and in parallel with the other cap looks like bodged trim for whatever reason. More likely they ran out capacitors they needed and hacked in whatever they had on hand to make the production go. I have never been impressed with Mastech. The one I own is a piece of garbage sitting in the corner.

author: klunkerbus
author_rank: Unknown
timestamp: January 10, 2017, 03:03:50 am
content: Quote from: pascal_sweden on January 10, 2017, 02:29:07 amActually, it looks like they tried. Looking at the photo again, I see C4, C5, C6 and C7 all have two sets of pads that are in parallel. You can see the traces joining the two sets of pads, and the same reference designator is on both sets of pads. Apparently the flexibility they could obtain with two capacitors in parallel didn't quite cut it.I'm not trying to defend what I caught in the picture, but I assume this is some sort of select-in-test tweaking that occurred in manufacturing. If so, the final capacitor values the units needed could have varied from unit to unit, and the number of parts involved could vary depend on what standard values were on hand and how closely the tech was trying to hit the optimum value.

author: klunkerbus
author_rank: Unknown
timestamp: January 10, 2017, 03:29:28 am
content: A bit more info, FWIW. I won't risk damage by probing, but C4-C7 appear to all connect to the pin 17-32 side of a FS9704B-PCE DMM analog front end chip. The typical application circuit for an FS9704 (page 10 ofhttp://www.ic-fortune.com/upload/Download/FS970X-DS-42_EN.pdf) actually shows variable trimmer caps on some of the pins. I didn't read through more of the datasheet to see if it explains how sensitive the part values are or what the calibration process is.

author: Rippey574
author_rank: Newbie
timestamp: March 02, 2019, 07:00:36 pm
content: Hate to resurrect this old post, but was wondering if the OP or any one else has the values for R1-R4, blew mine out and now the color bands are BL,BL,BL,BL.

author: ModemHead
author_rank: Frequent Contributor
timestamp: March 03, 2019, 04:44:51 am
content: Quote from: Rippey574 on March 02, 2019, 07:00:36 pmDoes this help?https://www.eevblog.com/forum/repair/if-you_ve-got-a-mastech-ms8050/

author: Rippey574
author_rank: Newbie
timestamp: March 04, 2019, 12:33:48 am
content: Perfect thank you!Quote from: ModemHead on March 03, 2019, 04:44:51 am

author: coromonadalix
author_rank: Super Contributor
timestamp: August 13, 2020, 11:24:06 pm
content: Reviving this thread ...Just found thisIt's a rebranded PeakTech 4000 meter and a service manual is availableyou'll be / should be able to repair the input resistors when they blow ??

author: coromonadalix
author_rank: Super Contributor
timestamp: August 14, 2020, 09:00:27 am
content: Calibration manual PeakTech 4000 same as the Mastech Ms8050Not sure if all meter based on the FS970X chipset can be calibrated the same way ??will be pushed to Ko4bb website

author: uargo
author_rank: Regular Contributor
timestamp: August 14, 2020, 02:17:38 pm
content: Quote from: pascal_sweden on January 08, 2017, 09:43:14 pmDon't buy a ms8050 for € 250 + € 50 shipping, it's not bad but it's quite old.Today buy a multimeter that has (AC + DC True Rms) not only (TrueRms)Buy a Vici or VICHY VC8145 is more modern, cheaper and people speak well of it, it is not the quality of a Fluke but it does not have the price of a Fluke either.The VC8145 costs € 133 + € 6 shipping, much better price and better features.https://es.aliexpress.com/item/32562456178.html?spm=a2g0o.productlist.0.0.45bc2165aPlhJ1&algo_pvid=202b7608-58d8-42a4-a746-b39c780a6a47&algo_expid=202b7608-58d8-42a4-a746-b39c780a6a47-23&btsid=0b0a050115974141973414935e56c3&ws_ab_test=searchweb0_0, searchweb201602_, searchweb201603_Or ET3240 in 182€ + 0€https://es.aliexpress.com/item/4000251706618.html?spm=a2g0o.detail.1000014.7.270878eeUdRcD0&gps-id=pcDetailBottomMoreOtherSeller&scm=1007.13338.177933.0&scm_id=1007.13338.177933.0&scm-url=1007.13338.177933.0&pvid=36c45c8a-5acd-4306-ae76-d8f9a27c732b&_t=gps-id:pcDetailBottomMoreOtherSeller,scm-url:1007.13338.177933.0,pvid:36c45c8a-5acd-4306-ae76-d8f9a27c732b,tpp_buckets:668%230%23131923%230_668%23808%234094%23730_668%23888%233325%2310_3338%230%23177933%230_3338%233142%239890%2310_668%232846%238110%23364_668%232717%237559%2366_668%231000022185%231000066059%230_668%233422%2315392%23999