Examples of AC adapters for electronic musical instruments, audio, and video equipment

We introduce custom development examples of AC adapters 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 high quality and technical expertise, including noise countermeasures and compliance with various safety standards.

About AC/DC Power Adapters — Desktop & Wall-Mount used in electronic musical instruments

Safety standards for electronic musical instruments

AC/DC Power Adapters — Desktop & Wall-Mount 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 is a key criterion for ensuring product safety and reliability.

Main differences from IEC60950 (compared to telecommunications equipment)

• LPS requirements: Mandatory evaluation and measurement for telecommunications equipment (IEC60950), but not required for audio equipment (IEC60065).
• X electrolytic capacitors: For telecommunications, residual voltage < 37% one second after power-off; for audio equipment, peak voltage must be below 60V two seconds after power-off.
• Leakage current: Telecommunications: 0.25mA, Audio equipment: 0.5mA.
• Operating temperature: Telecommunications: 35°C, Audio equipment: 45°C (both subtract 10K from component rating).
• Oil test (Softening Test): Unique to audio equipment; involves immersing parts in oil and gradually increasing the temperature up to 175°C to verify performance.

Oil test methods and evaluation criteria

Test method (reference):
The target parts are immersed in an oil tank, starting at an initial temperature of 100°C. The temperature is then raised by 50°C every hour, eventually reaching 175°C for final evaluation.

Acceptance criteria: Case indentation depth must be less than 0.1mm.

Up to four different test methods may be used.

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

Case study of recovery from safety standard failure

Supporting mass production with flexible responsiveness and technical proposals

In a development project for an AC/DC Power Adapters — Desktop & Wall-Mount for a radio product requested by major manufacturer S Corporation, a challenge occurred in the early stages where the product failed the safety standard tests. The main reason was that the polycarbonate (PC) resin used in the case did not pass the UL oil test.

To address this issue, Unifive worked closely with S Corporation to analyze the root cause in detail. As a result, without changing the overall design, we proposed an improvement to switch only the limited resin parts around the AC pin to a different material, achieving maximum effectiveness with minimal changes. Thanks to this, the retest was passed successfully, and the product smoothly transitioned to mass production.

Through this case, we further deepened our understanding of thermal effects and deformation risks associated with using the same resin, while establishing a method to ensure reliability through appropriate combinations of different materials. Today, this know-how is effectively leveraged to quickly and accurately respond to similar cases.

Unifive not only handles custom development of AC/DC Power Adapters — Desktop & Wall-Mount/power supplies, but also offers proven solutions for safety standards and design challenges. Even if you're just in the early consultation stage, feel free to contact us. With solid experience and responsiveness, we strongly support solving your business challenges.

Related content