FNIRSI® Portable CNC DC Power Supply - Review

In this article we’re reviewing an unusual mini power supply FNIRSI®.

1. Unboxing & First Look

Pic 1 Packaging

We’re unboxing a new power supply.

The packaging is very nice, and the device itself is quite unique. It consists of two parts — the control and display unit, and the power unit. The power unit looks very much like a large smartphone adapter.

Pic 2 Power supply adaptor

2. Specifications & Limitations

According to the advertisement, this device should output 30 volts and up to 5 amps — that’s 150 watts. But in reality, we’re seeing only 100 watts (see pic 2). So, 30 volts and 5 amps won’t happen. That’s just physics. Let’s plug in the adapter and turn the unit on.

Pic 3 Interface and Settings

The screen is beautiful and elegant. There are five control buttons and one side encoder. However, the control system isn’t very intuitive — you need to move a marker to select values, which isn’t the most convenient method. The menu includes various settings, including a screen displaying the manufacturer's logo.

3. Voltage Test

It’s not possible to set 30 volts and 5 amps. The adapter provides only 20 volts input, and under load, even less. Obviously — it’s a 100-watt adapter. So, the output tops out at around 18 volts (see pic 3). That’s a problem for our work, where we need at least 24 volts — for example, when repairing LEDs or blinds motors.

4. Current Limiting Test

Pic 4 Current Limiting Mode with Electronic load

Let’s test the current limiting mode. We set the limit to 4.1 amps and gradually increase the load starting from 3 amps. Once we exceed 4.1 amps, the power supply switches to constant current (CC) mode — great result. Now let’s see what current the power supply can actually deliver. We connect the 3715 electronic load and activate the power supply output (see pic 4). The backlit terminals look great. The current reading is nearly 5 amps on both the power supply and the load, with only a small voltage drop due to the wires.

First impression: a very stable output current.

5. Thermal Test

Pic 5 Temperature reading

Let’s check how the unit heats up, using a thermal camera. The images show a non-critical temperature — about 48°C or 118°F (See pic 5). That’s quite good.

6. Reliability (Burn-In) Test

Pic 6 PS shuts down by itself

Now for the reliability test. We set maximum voltage and current — about 19 volts and nearly 5 amps — and let it run continuously. After an hour or two, we expect to see if it holds up. But in this case, after just a few minutes, the power supply shuts down by itself, then restarts, then shuts down again (see pic 6). That’s a serious problem.

7. Conclusion

• Excellent design and compact size.
• But the advertised 30 volts are not available without a better adapter.
• Parameter controls are not very user-friendly.
• And worst of all — it’s unreliable under continuous load. In our test, the time to failure was less than 30 minutes. Whether it’s due to adapter overheating or cable contact issues doesn’t really matter.

Maybe your experience has been better — if so, let us know.