Case Study of AC/DC Power Adapter for Electronic Musical Instruments, Audio, and Video Equipment

We introduce custom development examples of AC/DC Power Adapter specialized for electronic musical instruments, audio equipment, and video devices. At UNIFIVE, we have received high praise from many major manufacturers in fields that demand advanced quality and technical expertise, including noise countermeasures and compliance with various safety standards.

About AC/DC Power Adapter Used in Electronic Musical Instruments

Safety Standards Applicable to Electronic Musical Instruments

AC/DC Power Adapter for electronic musical instruments, audio equipment, and video devices must comply with international safety standards such as IEC/EN 60065. This standard applies to both linear and switching types and serves as an important benchmark to ensure the safety and reliability of Products.

Main Differences from IEC60950 (Comparison with Telecommunications Equipment)

• LPS requirements: Evaluation testing is mandatory for telecommunications equipment (IEC60950), but not required for audio equipment (IEC60065).
• X electrolytic capacitors: For telecommunications equipment, residual voltage must be <37% 1 second after power-off; for audio equipment, peak voltage must be 60V or less 2 seconds after power-off.
• Leakage current: Telecommunications equipment: 0.25mA; Audio equipment: 0.5mA.
• Operating temperature: Telecommunications equipment: 35°C; Audio equipment: 45°C (in both cases, minus 10K from component specifications).
• Oil test (Softening Test): A test specific to audio equipment, in which materials are immersed in oil and the temperature is gradually increased up to 175°C for verification.

Oil Test Method and Evaluation Criteria

Test method (reference):
Immerse the target part in an oil bath starting at an initial temperature of 100°C. Then increase the temperature by 50°C every hour, heating up to 175°C for final evaluation.

Pass criteria: The case indentation thickness must be less than 0.1mm.

Four different methods may be used for this test.

*This information is based on past results as of December 1, 2020.

Case Study: Recovery from Safety Standard Non-Compliance

Contributing to Mass Production Through Flexible Response and Technical Proposals

In a development project for AC/DC Power Adapter for radio Products requested by a major manufacturer, Company S, an issue arose in the initial stage when the Products failed safety standard testing. The main cause was that the polycarbonate (PC) resin used for the case did not pass the UL oil test requirements.

To address this issue, UNIFIVE worked closely with Company S to analyze the root cause in detail. As a result, without changing the overall design, we proposed a highly effective improvement by switching only the limited resin area around the AC pins to a different material. With this measure, the product successfully passed the retest and smoothly transitioned to mass production.

Through this case, we deepened our understanding of thermal effects and deformation risks associated with using the same resin material and established a method to ensure reliability by appropriately combining different types of resins. This know-how now enables us to respond quickly and accurately to similar cases.

UNIFIVE provides not only custom development of AC/DC Power Adapter and power supplies, but also solutions based on proven experience for safety standards and design challenges. Even if you are at the stage of "just wanting to consult," please feel free to contact us. With solid experience and responsiveness, we strongly support your problem-solving efforts.

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