Daisy Ding(Ms.) Mob/Whatsapp/WeChat：+86 180 3022 1782 Email: sales3@nseauto.com
"Effective Troubleshooting Techniques for Power Supply Input and Output Issues"
Time:Jan 15,2026
Perform the test using a voltmeter
The first step is to use a voltmeter to test the power terminals. But is it more reasonable to test the input terminals or the output terminals first? The answer may depend on the nature of the fault.
If we observe that all the devices powered by this power supply are in the "off" state, then the power supply is likely the main fault point. Here is a key symptom that can help us diagnose the problem. Most power supplies have a "DC normal" or "power" indicator light. If the power supply is working properly, this indicator light will be on. If the indicator light is on, we can proceed to the second step, which is the load test.
If the indicator light goes out, it indicates that the power is not working. At this point, you should first check the input terminals. If the input terminals are receiving normal power supply, we can rule out the problem in the upstream circuit. Most power supplies provide alternating voltage, which can be single-phase or three-phase. Therefore, the voltmeter should be set to the AC voltage mode. If no voltage is detected, check the upstream fuses, circuit breakers or branch circuit breakers.
If the input voltage is within the acceptable rated range, the output voltage becomes the primary factor determining whether the equipment can receive normal power supply. The output terminal should be tested to obtain a value very close to the rated output voltage. When conducting this test, please use the DC voltage mode of the multimeter.
Voltage regulation
Industrial power supplies can sometimes perform voltage regulation within a small range to fine-tune the output. However, this is intended to compensate for load effects rather than to address faults that occur after long-term use. You should adjust the voltage at the time of system startup and installation after all devices are running. If the voltage drops suddenly after the power supply has been in operation for many years, the voltage regulation function should not be used to increase the voltage.
Line board test
Almost all control cabinets use terminal blocks to distribute power and control signals. The positive and negative poles of the power supply are usually transmitted through wires to these distribution points. If the power supply is difficult to access, find these terminal blocks to conduct voltage output tests.
Sometimes, the output voltage is too low to conduct the test, such as the USB data cable of a mobile phone charger. Sometimes, the connection terminals are extremely difficult to reach and are blocked by the cables. If the test is crucial, a splitter board can be purchased. These splitter boards can convert the thin or hard-to-reach cables into a larger circuit board with easier-to-operate connection terminals. I usually keep several of these splitter boards in my workshop.
Summary
A coherent multi-step process can isolate power failures. First, test the input voltage. Then, verify the output under no-load conditions and after connecting the load separately, so that the source of the fault can be traced. Finally, repair the fault or replace the power supply as needed. Power tests usually do not include tests on internal components, but for high-performance linear power supplies, testing of internal components can be useful. For switching power supplies, component-level tests are almost never conducted.
Blog
26 Dec,2025
Discussion on "How to choose the right industrial power supply for a server rack"
Almost all control cabinets require a DC power supply. Some control cabinets only use alternating current for motor control, but except for these exceptions, control cabinets also require direct current power to supply power to PLCS, Hmis, digital and analog I/O devices, relays and contactor coils. It is precisely the responsibility of industrial power supplies to provide these DC power sources.
16 Dec,2025
"PLC Fundamentals: Distinguishing Between Controller and Program Scope"
Each PLC manufacturer and each text-based code language developer defines variables in ladder diagram logic or code in a slightly different way.
11 Oct,2025
Learn About Bently Nevada 3500 Series Machinery Protection System
In the field of machinery monitoring, the Bentley 3500 Series has established itself as an industry benchmark for its exceptional performance, demonstrating irreplaceable advantages across the board, from core functions to application scenarios.
06 Oct,2025
"Exploring the Values and Culture of Sumset International Trading Co., Ltd."
At Sumset International Trading Co., Ltd., we believe a fulfilling career is inseparable from vibrant personal time.
15 Jan,2026
"Effective Troubleshooting Techniques for Power Supply Input and Output Issues"
Power supply testing is usually a relatively quick process, but without the correct information, the test results may be misleading. The difficulty of repairing different types of power supplies also varies. In many cases, once the faulty power supply is identified, replacing it is the most effective solution.
13 Jan,2026
Precision Performance with Accelerometer Acceleration Transducers for Advanced Condition Monitoring
Accelerometer Acceleration Transducers play a vital role in modern industrial diagnostics, enabling engineers to capture accurate vibration data and protect critical assets from unexpected failure.
About Us
Sumset International Trading Co.,Ltd
We are a supplier of automation spare parts and components from reliable and well-known brands. We mainly provide PLC modules, DCS control cards, ESD control cards, turbine monitors, vibration monitoring and asset protection systems.
Address:
Room 1904, Building B, Diamond Coast, No. 96 Lujiang Road, Siming District, Xiamen, China
Copyright @ 2025 Sumset International Trading Co.,Ltd. All Rights reserved