Re: Victor (RuoShui) 98A+ DMM 22000 Counts - Version 2024 - Page 1
Forum section: electronics / testgear

author: jebem
author_rank: Regular Contributor
timestamp: July 25, 2025, 05:50:27 pm
content: This 22000 count version seems to be the latest iteration from 2024 of the Victor/RuoShui 98A/98A+ model.An older version was excellently covered by member HKJ here:https://lygte-info.dk/review/DMMVictor%2098A%20UK.htmlThe 2024 98A+ version is currently seen at the RuoShui Official Store on AliExpress.Following Dave Jones motto, I took it apart on arrival. Well, that was after a very brief checking in case it was DOA.Now it rest in pieces while I take pictures and try to decipher the SMD IC markings.This is a somewhat complex handheld by today's standards for low cost DMM meters IMHO.Three PCBs with a lot of active and passive components.Among them, there is one Holtek HT32F52352 MCU, one CR506A-P1 (custom marking ?) DMM in LQFP64 package with a pinout that seems a match with the popular DTM0660L, two TM1621B LCD Drivers, and three BL24C256A 256Kbit EEPROMs.Some input protection is included in the form of two MOVs (one SURGING 162 1600V, and another unmarked one), and just one PTC (SCD102R 1000R).Unfortunately one 0.2A/250V and another 10A/250V 5x20mm glass fuses are used here.They claim CAT IV 600V and CAT III 1000V as seen in the front panel.I will post pictures of the internals next.

author: jebem
author_rank: Regular Contributor
timestamp: July 26, 2025, 06:49:20 am
content: The package includes a semi-robust card box, could be better.Inside the DMM properly packed (no pouch included); a key to open the back cover by rotating the locks by 90 degrees; good test leads, very soft to the touch and maleable, probably using silicone; the user guide in English; a DVD-RW (!) with the remote control software for Windows and Android; and the two-way IR to USB adapter.The DMM cabinet is made using two color injection molding. Very solid and soft to the touch.Battery compartment, piezoelectric buzzer, TX and RX IR LEDs, and flashlight at the back.The IR to USB adapter model P070102 inserted into the IR interface slot.Battery cover exposing the 3 x 1.5V "AA" battery compartment, the 10A and 0.2A 5x20mm glass fuses, and a 4-pad terminal (for what?).

author: jebem
author_rank: Regular Contributor
timestamp: July 26, 2025, 10:42:38 am
content: Inside the DMM there are Three PCB assemblies. The Main Board assembly is a multi-layer PCB.MAIN_BOARDSIDE A: 98C+ _MA_C320023-33 PCB-AVR1 SURGING 162 MOV VARISTOR 1600VPTC1 SCD102R SCD-102-102ARNF PTC Thermistor HV 1000RR1 YE-VI-BL-BL GD 470R 5W 5%R3 YW-VT-BL-OR GD 470KR 5W 5%R24 D000020 CUSTOM MARKING SIMILAR TO TC1746 BUT DIFF PIN SPACING: R1=1K, R2=10K, R3=100K, R4=1MR, R5=10MR19 0.01R 10A CURRENT SHUNTC1 473J630 MMKP82 47nF 630V 5%SIDE B: 98C+ _MA_C320023-33 PCB-BVR3 NO ID MOV VARISTOR, NO IDR20 BR-BL-BL GR 1R 1/2W 0.05% SMDR21 BR-BL-BL-BL 100R 1/2W ?% SMDR30 BR-BL-BL-GR BL 10MR 1/2W 0.25% SMDR34 BR-BL-BL-RE 10KR 1/4W ?% SMDR39 BR-BL-BL-OR 100KR 1/4W ?% SMDR23 104 100KR SMDZ1 M7 1N4007 1A 1000V - CLAMP DIODE mA INPUT Z1 & Z2 IN SERIE NEG GNDZ2 M7 1N4007 1A 1000V - CLAMP DIODE mA INPUTZ3 M7 1N4007 1A 1000V - CLAMP DIODE mA INPUT Z3 & Z4 IN SERIE POS GNDZ4 M7 1N4007 1A 1000V - CLAMP DIODE mA INPUTZ6 A8 BAS19, SOT-23, SWITCHING DIODE 120V 200mAU1 CR506A-P1 CUSTOM MARKNG (?), LQFP64 package, 22000 counts DMM, pinout connections matches the DTM0660L DMM ICX1 4.000 YXC 4.000MHzU2 S06LH ZXRE060H5, SC70-5, 1% 0.6V ADJUSTABLE PRECISION SHUNT REGULATORU4 3001 SGM3001, SC70-6, Low ON-Resistance, Low Voltage, SPDT Analog SwitchU3 721 SGM721, SC70-5, Low Noise CMOS Operational AmplifierU5 3001 SGM3001, SC70-6, Low ON-Resistance, Low Voltage, SPDT Analog SwitchU6 M67N LDO POWER SUPPLY REGULATOR, SOT-23-5 -IN 4.5V, OUT 3.3V (TP VD+ 3.3) for Digital sectionU7 M67N LDO POWER SUPPLY REGULATOR, SOT-23-5 -IN 4.5V, OUT 3.3V ( TP VDP+ 3.3) for DisplayU8 M67N LDO POWER SUPPLY REGULATOR, SOT-23-5 -IN 4.5V, OUT 3.3V ( TP VA+ 3.3) for Analog sectionD1 HT32F52352 HT32F52352 BY HOLTEK, 64 LQFP-A, 32-Bit Arm Cortex-M0+ MCUX2 16.000 YXC 16.000MHzD2 BL24C256A 256Kbit (32768KB) EEPROMD3 BL24C256A 256Kbit (32768KB) EEPROMD4 BL24C256A 256Kbit (32768KB) EEPROMT1 Y2 SS8550, SOT-23, PNPT3 Y2 SS8550, SOT-23, PNPT6 Y2 SS8550, SOT-23, PNPT7 Y2 SS8550, SOT-23, PNPT2 Y2 SS8550, SOT-23, PNPT4 Y2 SS8550, SOT-23, PNPT5 3407 AO3407, SOT-23, P-Channel SMD Mosfet 4.5V -Battery switch ON/OFF controlT8 1AM MMBT3904, SOT-3, NPNCN4 PCOM 4-PIN PAD. Left to right: BATT(-), R52(33R) to D1(52), R2(33R) to D1(51), BATT(+)DISPLAY_BOARDSIDE A: 79+_KDIS_C310134-10 PCB-ADISPLAY NO MARKING LCD DISPLAYSIDE B: 79+_KDIS_C310134-10 PCB-BD1 CM021B CD4021B by TEXAS, 8-STAGE STATIC SHIFT REGISTERSD2 CM021B CD4021B by TEXAS, 8-STAGE STATIC SHIFT REGISTERSD3 TM1621B MEMORY MAPPED LCD DRIVERD4 TM1621B MEMORY MAPPED LCD DRIVERT1 3407 AO3407, SOT-23, P-Channel SMD Mosfet - Backlight driverPWR/IO_BOARDSIDE A: 98A+_BB_IR_C310147-01 PCB-AH1 BR-BL-OR GO 10mH 5% inductorT2 1AM MMBT3904, SOT-23, NPNT3 1AM MMBT3904, SOT-23, NPN -BB1 Buzzer driverT4 Y1 SS8050, SOT-23, NPNT5 1AM MMBT3904, SOT-23, NPNT6 2A MMBT3906, SOT-23, PNPT7 2A MMBT3906, SOT-23, PNPSIDE B: 98A+_BB_IR_C310147-01 PCB-BTXD LED_TRANSP TX IR LEDRXD LED_BLK RX IR LEDLED1 LED_TRANSP FLASHLIGHT LEDBB1 10nF Buzzer piezo, CHASSIS MOUNT

author: jebem
author_rank: Regular Contributor
timestamp: July 27, 2025, 03:16:40 pm
content: When I dismantled this DMM, careless removed the Main Board assuming that the rotary selector was a self contained unit.I was wrong because the three switch contacts used in the selector are just siting there waiting to jumping around.One of them got loose and I had just left it there, so the posted pictures shows it in the wrong position.Attached is the correct position of the three switch contacts.

author: jebem
author_rank: Regular Contributor
timestamp: July 27, 2025, 04:08:47 pm
content: The calibration of this DMM is done by using its firmware calibration setup.There are no cap or pot trimers inside.No jumper soldering is required either (The three EEPROMs are controlled by the D1 MCU).A good source of voltage/current/resistance/capacitance is required to get the DMM properly calibrated.For calibration information, pls see the thread below.It is a very good information, including a full calibration document in Chinese (P021101_VC98AP2_0.docx) from what I believe is the original from the manufacturer.https://www.eevblog.com/forum/testgear/victor-98a-calibration/msg5713859/#msg5713859In my 2024 DMM version, the procedure to enter into calibration mode is similar to what is described above:1. Rotate the rotary selector to the OFF position;2. Press and hold the HOLD and RANGE keys;3. Rotate the rotary selector to the intended measurement function;4. Release the HOLD and RANGE keys.The DMM will turn ON but in CAL mode.Attached is a English translated version of the above P021101_VC98AP2_0.docx calibration instructions.

author: jebem
author_rank: Regular Contributor
timestamp: July 27, 2025, 06:30:14 pm
content: A few random measurements.98Aplus_1. European nominal 230VAC mains outlet - AC Volt reading (Comparing with a Alientek DM40C)98Aplus_2. European nominal 230VAC mains outlet - Freq.+AC Volt reading (Comparing with a Alientek DM40C)98Aplus_3. 9V battery - DC Volt reading (Comparing with a Alientek DM40C)98Aplus_4. 1KR 0.1% - R reading, Auto98Aplus_5. 0.1R 0.1% - R reading, auto, REL enabled98Aplus_6. 10MR 0.1% - R reading, Auto98Aplus_7. Two 100MR 5% HV resistors - R reading, Auto98Aplus_8. 4.5uF 5% Motor Start - Cap. reading, Auto98Aplus_9. 0.047uF 630V WIMA MKS - Cap. reading, Auto98Aplus_10. Open circuit, Cap reading, Auto - The infamous lockdown on capacitance selector that disable the use of REL to null the reading. I can only register capacitances above 300pF with a large error (20%) and good accuracy above 1nF.Besides that, the capacitance registering time seems to be proportional to the capacitance value, so very slow when reading capacitors above 1000uF.Otherwise this DMM seems to be precise and stable enough to compete against other models costing more than this one (I got it on sale for 78 EUR shipment included.