A TESMEN TSM-522S was provided free of charge to the channel for review. This multimeter is commonly sold on Amazon for $24.99.
What is the TESMEN TSM-522S?
This is a stylish compact handheld smart multimeter which has basic measurement functions and a simple-to-use interface. Household use for all age groups. It has 4,000 counts and true RMS, with automatic ranging on all modes.
Features:
Volts AC, Volts DC, Resistance, Continuity (These fall under the "Auto" Smart Mode)
Frequency, Capacitance, Diode, NCV, Live.
Auto Power Off, Low Battery Indicator, Hold, Bar Graph, Flashlight
3 Years Warranty
Missing Features:
No Current (Amperes), no Temperature, No REL (relative), No LED test, No Battery test
No tilt stand, no mounting options, no TESMEN online information, no PDF manual.
What comes with the unit?
The multimeter, test leads, 2 AAA alkaline batteries, Zipper carry pouch, user manual, all inside a nice shipping box. The multimeter, batteries, test leads are all individually wrapped in plastic. The multimeter also has a removable screen protector from the factory.
How is the construction?
Everything inside the package has high quality finish. The multimeter itself has a separable green (or blue) boot, for high grip and access to the batteries. Honestly, the case underneath the boot is gorgeous, so the the multimeter has a finished look with or without it. The molding is top notch and feels durable.
The boot wraps around the edges to the same height as the push buttons on the front, helping to protect against inadvertent activation. The buttons are easy to see and use. The battery bay access is good, however requires a (+) tip screwdriver. This one screw goes into a brass threaded insert for long life. The battery bay itself is well marked.
The 2.56 inch screen is backlit reverse LCD with colored backgrounds for different regions. Near the top there is a bar which lights green or red for different scenarios such as NCV and continuity. Strangely, this LED indicator bar is missing from some of the stock images. The screen has great contrast at all viewing angles except from the top-down angle, which is unlikely angle to be viewing from. Outdoors the visibility is acceptable but could be better. It would be nice if they had used a photocell to detect ambient brightness and adjust accordingly.
The test leads are above average construction. They are the high quality PVC with appropriate protection for CAT III 600V rating. Without the push-on caps, a CAT II 600V rating. I measured both leads, they were a consistent 50 milliohms. The tips are medium sharp and plated nickel (not gold). The grooves near the end of each tip are designed to help reliably seat on wires or leads, in case you didn't know.
The User Experience
The unit has snappy performance, from the time it is turned on, through the measurements. The auto mode features an animated needle, indicating it's ready to measure just about anything in the blue portion of the dial. A press of the FUNC will enable you to manually select all ranges from left to right. Holding the FUNC button will return you to the Auto mode. A pleasure to use.
Auto power-off happens after 15 minutes of inactivity. It can be disabled by holding the FUNC button while powering the unit on. When APO is enabled, the Ø is displayed at the top left. If the battery voltage is getting low, a low battery icon will appear at the top right. You'll always have this icon if you decide to use rechargeable 1.2V cells. The unit is happy running all sorts of battery chemistries from low voltage NiMH to higher voltage Lithium Primaries. The long spring terminals accommodate all sizes.
Current consumption: 31 mA in auto mode, 48 mA with flashlight engaged. Quiescent current (device off) 21 μA.
Screen refresh time is around 3 times per second. If you are using a manual mode, removing the test leads from the circuit has an immediate effect on the displayed reading. However, if you are in the auto mode, the last reading will persist on the screen for a second or more. I like this generally, might be a matter of preference.
The lack of tilt stand is a bit disappointing. It's only for hand-held or table-top use. You might use a cell phone holder or something else creative. The test leads they provide you have a right angle exit, so there are possibilities to prop the unit up by a random object.
The input jacks are not color coded - only gray plastic. However, the colors marked on the unit above the jacks are very clear and difficult to miss.
Those words silkscreened on the face are large and uncomplicated. The screen digits are all large too. As a result, it's easy to read EVERYTHING at a glance - perfect for those with aging eyes.
Voltage Measurements
If the voltage is below 0.8V, you'll need to switch out of the AUTO mode, and into the manual voltage mode. In the DCV range, there is wide coverage of voltages: from 0.1 millivolts to 600 volts. I measured 11 milliohm input impedance. The accuracy specification is 0.5% +3 counts, I found my test unit used all of that range, but only on the high side.
As for AC voltage, I found the measurement 0.9% high compared to my calibrated meters, they promise 0.8% +3 counts.
Resistance Measurements
There is also a wide range of resistance measurements from 0.1 Ω to 40 MΩ. An accuracy of 1% +5 counts was promised. I found it delivered on that. The test current is safe for testing low-current fuses: On a short circuit, the test current was only 0.1 mA.
Diode Measurements
This meter puts out only 1.84 volts in the diode mode, up to 0.7 mA. Therefore, it's only capable of measuring standard diode junctions. LED's were barely lit, with no voltage measurement appearing on the screen for any color I tested. A 0.19V Schottky diode measured 0.166V, a 0.60V silicon diode measured 0.579V.
Continuity
This worked acceptably fast in the manual continuity setting. In the auto mode, there is the typical pause. Immediately upon recognition, the beeper sounds and the bar above the display turns green. After another half second, the display starts indicating the resistance reading.
The loudness of the beeper is OK for quiet indoor space. I suspect many people would find it too quiet for loud areas or outdoor spaces.
Capacitance Measurements
Simply stated, the meter struggled to measure large capacitances. Near the upper limit, it took a very long period of time to display the reading. It appears 4 mF is the limit for this meter. I tried multiple capacitors above 4 mF and they all resulted in OL.
Strangely, all tables in the user manual have a "4" in the range. 4V, 4Ω, etc. So it seems the table in the owner's manual seems to be for another meter.
With further investigation, I found the GVDA GD136B is it's fraternal twin with a standard black-on-white LCD, and it's limit on capacitance specified as 4 mF max. Same with HABOTEST HT125B.
Even so, the accuracy met the rating in general. I think most people will be OK with the range but a little disappointed in the speed of measurement.
NCV/Live Functionality
NCV means Non Contact Voltage. Test leads should not be inserted. Instead, the upper region of the meter needs pointed in the direction of the live circuit. As you approach an insulated wire or socket that has live AC voltage, the unit will firstly display a green LED near the top, and the screen will display "---L" for low. As you get closer, the beeps will get faster, the LED indicator will change from green to red, and the display will show "---H" for high.
I brought the unit up to a 2-wire AC line for the differentiation test. Almost all meters I have pass this test, beeping fast on the hot side and slowly or not at all on the neutral side. The TESMEN unit was too sensitive to pass this test because it displayed "---H" for both wires. Therefore, it will indicate AC voltage is present but is too saturated to be able to distinguish which wire is the hot one.
Live is used by inserting the red lead into the receptacle socket until there is metal-metal contact. Unfortunately, this means you'll need to take the high voltage cap off of the tip to insert it. So be careful! "Lose the Cap, Lose a CAT"
When touching the prong to Neutral or Ground, there is no change to the display. When touching Live, the display will show "---H", the LED bar will light up red, and the beeper will beep rapidly. I found this worked very well - a black & white result happens every time.
Frequency
Reportedly, this meter covers 1.00 Hz - 200 kHz. However, it's fraternal twins promise up to 4 MHz. Perhaps another specification error? I will test this in the future and include my results here as I expand my test coverage across the devices I own.
Flashlight
The location of the flashlight is the top of the back side of the unit, not the end. This enables the manufacturer to place the white LED on the PCB, instead of being attached as a secondary operation. The lens focuses the light from the rectangular surface-mount cool white emitter onto whatever you have it aimed at. It works OK, the beam and intensity are typical for these types of devices. I chose an almost dark room for the following image:
The Teardown
Well, I opened the back, that's as far as I think I needed to go. You can see those flashlight features. Also, you can see how the front of the unit nests into the perimeter of the back. I think this is "blast" proof design, and helps to keep out the elements. No shielding.
The screw standoff posts are buttressed by extra plastic webs and by the surround from the back side. I think this unit would survive more drops than it's competitors at a similar price point. The battery bay is almost fully closed and isolated from the inside, distanced away from the PCB enough that a leaky alkaline battery will cause negligible damage.
Above the battery bay is the bump where the bay screw insert is installed. Interestingly, the bump appears to pass through the PCB to touch off at the front molding at the center of the buttons, adding strength should the unit be squeezed hard. It should make the user experience better, because pressing the buttons on the front side won't make the face flex.
The four assembly screws aren't using threaded inserts, but there should be no reason you need to access the inside of the unit due to no fuses. Instead, protection comes from of a PTC thermistor, MELF resistors, and "Zener clamp" transistor pairs.
A close-up image of the internals show a COB processor, TM1621B LCD display driver, a solid state relay, and integral NCV detector on the PCB. The loudness of the beeper and brightness of the LEDs are potentially altered by changing some of the resistors along the top side. The beeper excitation is probably creating the proper volume, it's just not getting outside the case to your ears because the entire unit is sealed up to the environment so well.
In case you didn't notice, the PCB is marked with the HABOTEST HT125B model number.
Split terminals are mechanically decoupled away from the PCB with excellent HV separation.
In Summary
The TESMEN TSM-522S is a good buy. It comes with plenty of quality and no bad behaviors. I didn't see any abhorrent shortcuts or engineering flaws.
I hope I've made it clear what the unit will and will not do. To emphasize them, let's do pros and cons.
Pros
Easy to use, easy to read. Small, grippy, modern. Gorgeous display.
Looks good with or without the silicon wrap. Nice body to look at.
Superb quality case and boot material, sturdy mechanical design elements
Better-than-required flexible 10A test leads.
Smart mode and auto ranging works without errors, last reading persists on screen.
Very good voltage and resistance range and performance.
CAT III 600V seems legit.
NCV very sensitive (some will like this); Live works perfectly.
Has a flashlight.
Batteries Included, various 1.2-1.7 V cells also work and fit just fine.
A leaky battery is mostly contained; not likely to migrate to the functional area.
3 year full warranty.
Nice Multilanguage user manual.
Cons
Truncated capacitance range 1nF - 4 mF. Owners manual promised 0.001nF - 60 mF.
Slow getting a capacitance result.
Over-sensitive NCV mode doesn't help differentiation.
Beeper is somewhat quiet inside the nearly-sealed case.
Display is one brightness only, same with flashlight.
No tilt stand (but could be propped)
No current testing
No LED testing
No REL feature, no min/max.
No temperature reading
No battery test mode
No user calibration
No online product information from TESMEN
No electronic user manual (PDF)
Battery changes could be easier, requires pulling off a tight boot and use of screwdriver.
Hope you liked this review and you found it worth your time to read. Keep On Testing!
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