Protek D620: 100,000 count forgotten multimeter. - Page 1
Forum section: electronics / testgear

author: jchw4
author_rank: Regular Contributor
timestamp: May 15, 2023, 12:21:46 pm
content: I got my hands on a very unusual 100,000 count multimeter with trend capture: Protek D620.The information on the web is very scarce: I was able to find only a few datasheets, User Manual in Polish (only!) and a Calibration Manual.This site has some data and photos:https://www.gotronik.pl/multimetry/protek_D620.HTMLWeb archive has only a single partial capture of the product pagehttps://web.archive.org/web/20040811163957/http://www.protektest.com/ProdInfo.asp?prodId=620.I could not find a software for this meter in any "Download Software" captureshttps://web.archive.org/web/20080129111348/http://www.protektest.com/ProdDnLd.asp?type=SW.If somebody has software or a user manual, please share!Somebody on this forum mentioned that there was a protocol description somewhere. Anyone?

author: jchw4
author_rank: Regular Contributor
timestamp: May 15, 2023, 12:23:19 pm
content: The meter was dead, consuming 100mA at 3V from my power supply even when off.After disassembly, the damage was clear.U11 mark was difficult to read, but it turned out to be TPS763 5.0V LDO (SOT-23-5 marked PBGI). Replaced with recommended TPS709.R3 was nearly unreadable too, but turned out to be marked "10R0" and still measured 10 Ohm!

author: jchw4
author_rank: Regular Contributor
timestamp: May 15, 2023, 12:24:56 pm
content: The meter looks very nice, has 100,000 counts in all ranges, live trend capture and glowing buttons! Not really as sci-fi looking as my phone decided to present, but still nice.Meter seems to be in spec compared to my DMMCheck+ except 100k ohms range, which is significantly off. Did not investigate this yet.My main concern was about pretty long whiskers that grew out of the fuse holders. Most of them fell off before I was able to capture them but here is a photo.

author: jchw4
author_rank: Regular Contributor
timestamp: May 15, 2023, 12:26:50 pm
content: Meter PCBs.

author: Gyro
author_rank: Super Contributor
timestamp: May 15, 2023, 01:20:29 pm
content: That looks like a nicely featured meter for decent resolution, display functionality and data logging.Treat the indicated CAT ratings with utmost suspicion though, there's no way that they align with the PCB photos.

author: coromonadalix
author_rank: Super Contributor
timestamp: May 15, 2023, 02:44:27 pm
content: the meter chipset must be hidden under the lcdi see a nec mcu but ??Oh sorry there is another piggyback pcb it seemsNice find loll lucky you lollI do remember one other meter / brand who had 80,000 count display,but cant recall the modelEDIT Protek 6800

author: Kleinstein
author_rank: Super Contributor
timestamp: May 15, 2023, 03:37:01 pm
content: I don't think this meter is using a normal DMM chip set. There is a 24 Bit SD ADC (CS5522) and lots of CMOS switches. So chances are this is more like a µC (the large NEC part), ADC chip and range and function switching with the CMOS switches. The 100000 counts may still be quite conservative for the ADC, but the reference could well be limiting.

author: coromonadalix
author_rank: Super Contributor
timestamp: May 15, 2023, 04:15:09 pm
content: yeah damn eyes, the row connectors are between the front panel and meter section ...Some APPA metres go to 100k countshttps://www.eevblog.com/forum/testgear/rs-pro-dmm-the-idm505-100-000-counts-0-015-dc-v-accuracy/

author: johansen
author_rank: Super Contributor
timestamp: May 15, 2023, 04:18:56 pm
content: I have one of these, but need a high voltage source to calibrate it..it reads about 15% high on all ranges as my friend didn't get all the way through the procedure.

author: NoisyBoy
author_rank: Frequent Contributor
timestamp: May 15, 2023, 06:33:43 pm
content: Odd choice for button backlight, when each button looks the same without any writing on it. They must assume the user would remember the function of each button.

author: jchw4
author_rank: Regular Contributor
timestamp: May 21, 2023, 12:04:54 pm
content: I placed a thermistor on top of LT1004, fired up air con and did some logging of a LM399A-based 10V reference.(Extracting data from the screen photo is pretty painfulCould somebody share the orifigal communication software and a user manual? Anyone?)Playing with numbers I created a pretty close approximation of the value based on temperature (see PPM graph). So it seems like my meter has about 90 PPM/C.It certanly worth improving. Install MAX6325 instead of LT1004? But I don't have equipment to calibrate it later, so it's probably not going to happen.Upd: reattached the photos.

author: jchw4
author_rank: Regular Contributor
timestamp: May 21, 2023, 12:09:01 pm
content: Quote from: NoisyBoy on May 15, 2023, 06:33:43 pmIt's not backlight. It's glow-in-the-dark plastics

author: CHIMVO
author_rank: Newbie
timestamp: July 17, 2025, 12:51:22 am
content: The original software for the PROTEKD620 meter comes on a CD with the multimeter; I'll have to find the manual.Does anyone have any calibration information or the .bin file for the EPROM?

author: JoeyP
author_rank: Frequent Contributor
timestamp: July 17, 2025, 01:01:28 pm
content: Seeing your photo of whiskers reminded me that I recently came across the worst case of tin whiskers that I've ever seen. This was inside of a cheap TV coax splitter that had been sitting dormant for a number of years. I know this doesn't help you calibrate your meter, but thought some might find it interesting

author: CHIMVO
author_rank: Newbie
timestamp: July 17, 2025, 02:50:14 pm
content: I found the Protek D620 manual. The software is for Windows XP or earlier. I tested it on Windows 7, and it doesn't work.Can anyone help me calibrate the D620 multimeter?Does anyone have the .bin file for the U5 and U7 Eproms?Thanks.