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The other day I looked at a $25 USB meter that was perfect for those who want to test if USB ports and devices such as chargers and power banks are working properly. It's a great tool for those dabbling with gadget repairs.
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But if you're more serious about diagnostics and repair, and have a slightly bigger budget, then you should get your hands on a full-blown USB multimeter packed with all sorts of features, from the ability to log data to identifying whether your cables support high-power charging.
This tool is the Fnirsi FNB58 USB tester.
The FNB58 is an all-in-one USB tester for USB-A, microUSB, and USB-C ports. You can plug into a USB-A port directly, and to microUSB and USB-C using cables.
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The display is a bright, crisp, clear 2.0-inch TFT LCD display, beating hands-down many other USB multimeters on the market, and making it much easier to read the information being displayed.
With a built-in orientation sensor, the FNB58 automatically adjusts the display to accommodate the device's orientation. The tester features an intuitive rocker switch and a back button for straightforward navigation.
But this simplicity hides a lot of power, and I suggest downloading and getting real familiar with the user manual, because there's a lot to this gadget and it's easy to find yourself facing some scary-looking warnings.
One feature of the FNB58 that I really like is the real-time voltage and current waveform screen that gives me an at-a-glance idea of what the meter is sensing, which can dramatically speed up a diagnosis. For intermittent faults, the meter can log up to 9 hours of waveform data.
Another useful feature is the ability to read E-mark chip data found in higher-quality USB-C cables. This chip allows the cable to communicate with the devices it connects to, providing information about the cable's capabilities, power capacity, and supported features.
The Fnirsi FNB58 is a powerful, versatile, and, at just over $50, affordable USB test meter. Not only does it give you the usual volts/amps power information, but can see this information as a waveform, and even do multi-hour data logging. It can read E-mark and DASH cable data, carry out cable resistance tests (this can uncover internal cable damage that is otherwise invisible), display what charge protocols are being used, and much more.
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That's quite a list of features, and it's far from complete.
The display is one of the best I've seen on a USB meter, and the user interface is simple. But there's a lot more to this meter, and I recommend reading, re-reading, and then reading again the manual, and spending time experimenting with the meter to get used to what it can do and what to expect from it.
If you want a cheap meter, the KJ-KayJI 2 in 1 USB tester is a good, sub-$25 option, but if you want more functionality and capability, the Fnirsi FNB58 is a huge step up for little more than double the money.