Yokogawa 205120 is the compact catalog form of Yokogawa 2051 20. It is a discontinued, permanent-magnet moving-coil analog DC voltmeter—not a modern digital multimeter. Its ranges are ±3, ±10, ±30, ±100 and ±300 V DC, with 10 kΩ/V nominal sensitivity. Yokogawa lists the TY520 digital multimeter as its replacement.
What the Yokogawa 2051 20 is
Yokogawa’s official product page formats the model as 2051 20; listings that concatenate the family and suffix may show 205120. The instrument belongs to the discontinued 2050 Series of miniature portable ammeters and voltmeters. Model 2051 20 is specifically a DC-voltage instrument. Other 2050-Series models covered current or AC measurements, so the family name should not be used to imply that every variant is a general-purpose multimeter.
It uses a permanent-magnet moving-coil movement, a mirrored scale and a red bladed pointer. Models 2051 and 2052 use taut-band suspension in the moving parts to reduce friction and improve shock resistance. See Yokogawa’s discontinued-product page and the 2050 Series brochure.
Yokogawa 2051 20 specifications
| Specification | 2051 20 |
|---|---|
| Instrument type | Analog DC voltmeter |
| Movement | Permanent-magnet moving-coil |
| Maximum scale values | ±3, ±10, ±30, ±100 and ±300 V DC |
| Nominal sensitivity | 10 kΩ/V |
| Approximate full-scale movement current | 100 µA |
| Accuracy classification | JIS C 1102:1997 Class 1.0 |
| Operating position | Horizontal |
| Scale length | Approximately 135 mm |
| Deflection angle | 90° |
| Pointer | Red bladed needle |
| Operating environment | 0 to 40 °C; 30% to 75% RH |
| Storage environment | −10 to 50 °C; 25% to 80% RH |
| Approximate dimensions | 113 × 106 × 46 mm |
| Approximate mass | 0.35 kg |
| Optional carrying case | 2291 02; brochure references also include B9604WM and 93042 |
| Status | Discontinued December 27, 2019 |
| Yokogawa-listed replacement | TY520 digital multimeter |
Class 1.0 is Yokogawa’s classification under the cited Japanese standard; it should not be restated as a universal ±1% digital-meter accuracy specification under every condition.
#1 Best Overall
- Various Monitoring Parameters: The power meter plug can monitor the power (W), energy (kWh), volts, amps, hertz, power factor, cost, minimum and maximum power (W), cumulative days and time of your appliances. By switching 7 display modes, you can easily know the various parameters while the appliance is working. The home energy monitor can also calculate and display how much power your appliance uses and how much electricity bill it cost in cumulative time
- Upgraded LCD Display: With large screen size 2.36 inch x 1.85 inch, clearer monitor backlit, our electrical usage monitor can display the data clearer and more visible no matter day or night. 180°full wide viewing angles is great for reading and recording the data in any angles. No need to stand on the front of the display and bend over to read the numbers
- Adjustable Backlight Time: Our upgraded watt meter has 5 options of backlight time. The default backlight time duration is 10 minutes(bL-0). If you want to change the backlight time, you can press and hold "UP" and "DOWN" button at the same time to enter backlight time setting, then press "UP" and "DOWN" to select the backlight time (bL-0 =10 minutes, bL-1=1 hour, bL-2=4 hours, bL-3=8 hours, bL-4=always on), finally press the "COST" to save the backlight time settings
- Overload protection: When the power of the appliance exceeds the overload power, the LCD will display “OVERLOAD” to warn the user. All the buttons will quit working and can only be workable when you lower or remove the load power. The default overload power is 3680W and is adjustable from 0 to 3680W. In general, you need to set the overload power to 1800W before using. Just press the "function" button for more than 3 seconds to enter the setting
- Data Memory Function: The wattage meter will record your power consumption data when you remove it from socket, or remove appliances from the electricity monitor. You can directly see the last data when you use it next time. This function can also automatically save the data when there is a sudden power failure
What 10 kΩ/V means
The sensitivity specifies the approximate input resistance per volt of selected range. Values below are calculated from Yokogawa’s 10 kΩ/V figure:
| Selected range | Approximate input resistance |
|---|---|
| 3 V | 30 kΩ |
| 10 V | 100 kΩ |
| 30 V | 300 kΩ |
| 100 V | 1 MΩ |
| 300 V | 3 MΩ |
That resistance can load a high-impedance circuit and pull its voltage down. A modern electronic DMM usually disturbs such circuits far less. The 2051 20 is therefore most suitable where the source impedance is low enough, a pointer display is wanted, and DC-only measurement is acceptable.
Rank #2
- CAT III 600V Safety Rating: Ensuring your safety when working on electrical systems in common residential, commercial, and industrial settings.
- AC/DC Voltage and Current Measurements up to 1000V and 10A: Allowing you to get accurate readings for a variety of electrical applications.
- Resistance, Continuity, Capacitance: Essential measurement functions for troubleshooting electrical issues in a wide range of systems, allowing you to quickly diagnose and repair problems.
- Diode Test: Allows you to quickly and accurately identify faulty diodes, saving you time and money on repairs.
- Temperature measurement: Provides easy monitoring of heating and cooling systems up to 400C with included type K thermocouple.
Using the meter correctly
- Inspect and zero-check: with no applied voltage, confirm that the pointer returns smoothly to zero. Do not use a sticking or damaged movement.
- Start on the highest suitable range: connect across the circuit, then select a lower range only when the reading is safely within it. Never exceed the selected full-scale value.
- Observe polarity: a moving-coil meter is polarity-sensitive. Reverse leads can drive the pointer in the wrong direction.
- Read the matching scale: use the scale corresponding to the selected range and read the mirror image straight-on to reduce parallax.
- Keep it horizontal: Yokogawa specifies horizontal operation; position affects the movement and indication.
- Allow the pointer to settle: record the value after mechanical motion has stopped, and compare questionable readings with a calibrated reference.
These are general moving-coil meter practices. For terminal details, connection diagrams and model-specific precautions, use the instruction material linked from Yokogawa’s product page rather than assuming a generic terminal layout.
Safety limitations
A 300 V scale marking is a measurement range, not proof of a modern 300 V safety rating. The discontinued 2051 20 is not documented on the cited product page with CAT II, CAT III or CAT IV protection. Yokogawa’s 250 V “linemax” statement applies to ammeters in the series and must not be transferred to this voltage-meter variant.
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Rank #3
- CAT III 600V Safety Rating: Ensuring your safety when working on electrical systems in common residential and commercial settings
- AC/DC Voltage Measurement up to 1000V: Quickly and accurately measure both AC and DC voltage in a wide range of applications, from automotive systems to electrical panels to commercial equipment.
- AC/DC Current Measurement up to 10A: Accurately measure AC and DC current for diagnosing electrical problems such as overloading, short circuits, and faulty wiring.
- Voltage, Resistance, Continuity, Capacitance: Essential measurement functions for troubleshooting electrical issues in a wide range of systems, allowing you to quickly diagnose and repair problems.
- Input Terminal for AC/DC Current Measurements to 10A: Allowing you to get accurate readings for a variety of electrical applications.
- Do not connect an unknown or modified unit directly to energized mains.
- Inspect insulation, terminals, enclosure, selector parts, movement, corrosion and evidence of liquid ingress.
- Verify lead integrity and the correct terminal arrangement from the applicable documentation.
- Use a known low-voltage DC source for an initial functional check, increasing voltage gradually.
- Have a used instrument assessed and calibrated before safety-critical work.
For comparison, the current TY520 is explicitly specified as 1000 V CAT III and 600 V CAT IV. Those ratings do not apply retroactively to the 2051 20.
Datasheet, brochure and support documents
The primary specification and discontinuation reference is Yokogawa’s 2051/2052/2053 product page. The family overview and model tables are in the BU2000-E brochure. Yokogawa’s support area separates product specifications, brochures, instruction manuals, drawings and discontinued-product resources. A service manual or calibration certificate should not be assumed to be publicly available unless Yokogawa confirms it directly.
Rank #4
- Accurately Test Full Features: Accurately measures AC/DC voltage, DC current, resistance, continuity test, diode and batteries.
- High Quality & Safety :Our multimeter is designed to safely and accurately troubleshoot a variety of automotive and household electrical problems. Overload Protection on all ranges to ensure long-term service life,Low Battery Indication, Audible continuity sensor checks that the circuit or wires conduct electricity. Double insulation with a good angled stand for hand free use.
- EASY TO USE: 2.7"Large Backlit LCD Display, Data Hold, Easy to Read Large Back-light Screen forvisibility in dimly light areas. Our mutimeter tester is widely used in Car repair, Homeuse, Schools, laboratories, Families and factories, suitable for Car Drivers, Beginners,Professional Electricians, Housewives, Students Use.
- Nice Protective Orange Shell with Stand Built: Our digital multimeter can be hand held or stood using its fold out stand. Removable thick rubber cover is made of kind of non-slip slightly soft plastic that will help with drop protection & minor bumps protection.
- 2 YEARS Quality Guarantee & Included 9V Battery: The compartment lid at the back is easy to remove. Battery/Set of Test Leads/User Manual are Included.They guarantee against faulty materials and workmanship for 2 years-giving you total peace of mind. If there is any issue within24 months of your purchase, we will replace it for vou with no doubt.
Is it discontinued?
Yes. Yokogawa records the 2050 Series as discontinued on December 27, 2019. New supply is therefore likely to mean old stock, while most marketplace examples will be used equipment. No current official public price for the 2051 20 is established; value depends on condition, calibration, accessories and provenance.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.TY520 replacement: successor, not equivalent
Yokogawa designates the TY520 as the replacement, but it changes the instrument fundamentally:
Best Value
- Additional Tips - The following incorrect operations may cause the multimeter not to show results: Firstly, the plugs of test leads are not fully inserted or not inserted into the correct sockets. Secondly, the manual rotary switch is not placed in the correct position. In addition, this meter can not test all AC Current and below 100mV AC Voltage. Please check the user manual carefully before measurement.
- Versatile Digital Multimeter - Accurately measures AC/DC Voltage, DC Current, Resistance, and Diode. This Multimeter is a really useful tool for solving industrial and household electrical issues. Suitable for Household Outlets, Fuses, Batteries (including Vehicles), Automotive Circuit Troubleshooting, Charging Systems, Testing electronics in Cars etc.
- Troubleshooting with Accuracy - This Multimeter has a sampling speed of 2 times per second; Built-in a backlight LCD display with 3 ½ digits (1999 count) 0.6”, and high polarity including negative and positive readings.
- Ensures Safety - Double fuse is anti-burn and protects from overloading. The silicone cover can protect the multimeter from failing damage and prevent electric shocks. And low battery indication will be displayed when battery power is low.
- Ease of Use - Support Data Hold and Continuity Buzzer. Includes Convenient feature like LCD Backlit Screen makes it easy to use in dimly light areas. Batteries/Set of Test Leads/User Manual are Included.
| Consideration | 2051 20 | TY520 |
|---|---|---|
| Display | Analog pointer and mirror scale | 3.5-digit, 6000-count LCD with 31-segment bar graph |
| Core measurement | DC voltage | DC/AC voltage and current, resistance, frequency, capacitance, temperature, continuity and diode test |
| Voltage capability | Up to ±300 V DC scale | Up to 1000 V, function-dependent |
| Input behavior | 10 kΩ/V loading characteristic | Modern electronic DMM input circuitry |
| Safety classification | Do not assume a modern CAT rating | 1000 V CAT III; 600 V CAT IV |
| Status | Discontinued | Current product page |
The TY520 includes true-RMS measurement, automatic and manual range features, hold functions, relative/percentage calculations, backlight and auto power-off. Detailed function-by-function ranges and accuracy are in Yokogawa’s DMM specification document; “0.09%” should not be treated as a single accuracy figure for every function.
When another meter is better
Choose the 2051 20 when
- You specifically need an analog pointer response.
- You are restoring legacy equipment or demonstrating analog measurement.
- You only need DC voltage and understand circuit loading.
- The unit’s condition and calibration can be verified.
Choose a modern DMM when
- You need AC, resistance, continuity, capacitance, frequency, temperature or current measurements.
- You need high input impedance, autoranging, logging or digital resolution.
- You require explicit CAT safety ratings, current support and calibration services.
TY530 and TY700 options
The TY530 adds features such as maximum/minimum/average values, memory, communications and logging of up to 1600 data points. It is useful when those functions matter, but unnecessary for basic voltage troubleshooting. Yokogawa’s TY700 series is a higher-end family rather than a form-fit or behavior-equivalent replacement; compare the exact model, safety rating, availability and required functions.
Quick Recap
Used-equipment buying checklist
- Request a clear photograph of the actual model marking and scale face; sellers often merge “2051” and “20” or confuse nearby variants.
- Check smooth pointer travel, zero return, taut-band movement, mirror, window, case, feet, terminals and selector mechanism.
- Look for corrosion, cracks, impact damage, liquid ingress, altered wiring and non-original repairs.
- Confirm test leads and carrying case rather than assuming accessories are included.
- Test first on a known low-voltage DC source and compare with a calibrated reference.
- Do not treat a visual pass or a seller’s “working” claim as proof of calibration or mains safety.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
