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Specifies requirements for warranty claims, including proper usage and authorized repairs.
Requirements for qualified technicians and suitable working environments.
Accessing technical data and critical mains power safety procedures.
Safe methods for opening, servicing, and reassembling the equipment.
Procedures for verifying service work and guidelines for safe transportation.
Ensuring correct operation and methods for diagnosing equipment issues.
Information on obtaining replacement parts through distributors or service centers.
Visual guide to external components and their part numbers.
Visual guide to internal circuit boards and modules with part numbers.
Identification of specific screws used for panel, fader, side moulding, and base.
Details on nominal and maximum input/output levels for various channels.
Technical data on the frequency response characteristics of the audio mixer.
Information on Total Harmonic Distortion plus Noise for different signal paths.
Details on analogue headroom, USB connectivity, and audio codec specifications.
Measurements for mix noise and microphone pre-amplifier EIN.
This document serves as a service manual for the ZED 4 bus series of mixers, specifically covering models ZED 420, ZED 428, and ZED 436. It provides essential information for servicing, maintaining, and understanding the internal and external components of these audio consoles.
The ZED 4 bus mixers are designed for professional audio applications, offering a comprehensive set of features for mixing multiple audio sources. They are equipped with various input and output channels, including mono and stereo inputs, auxiliary sends, and group outputs, allowing for flexible signal routing and processing. The consoles feature a robust construction suitable for both studio and live sound environments. Key operational elements include gain controls, frequency equalization (boost/cut), auxiliary sends, pan controls, and faders for precise level adjustments. The presence of a talkback system and headphone output further enhances their utility in monitoring and communication during live performances or recording sessions.
For usage, the ZED 4 bus mixers are intuitive, with clearly labeled controls for each channel and master section. Users can connect a variety of audio sources, such as microphones and line-level instruments, to the mono and stereo input channels. The gain controls allow for proper input level staging, while the frequency equalization section provides tools for shaping the tone of individual channels. Auxiliary sends enable the creation of monitor mixes or effects sends, and the pan controls allow for positioning sounds within the stereo field. The faders provide fine control over channel and master output levels. The master section includes controls for the main stereo output, group outputs, and a matrix output for additional routing flexibility. The headphone output allows for private monitoring of the mix, and the talkback system facilitates communication with performers or other crew members.
Maintenance of the ZED 4 bus mixers is detailed in this service manual, emphasizing the importance of qualified service personnel for any repair work. The manual outlines several servicing precautions and general notes to ensure safety and proper repair procedures. Service personnel are advised to be technically qualified, especially when dealing with mains power supplies or surface mount circuit assemblies. Adequate service facilities, including a clear work surface, proper lighting, and correct tools, are essential. Before starting any service job, technicians should ensure they have all necessary information, which can be found on the Allen & Heath website or by contacting technical support.
Regarding mains power, it is crucial to connect the equipment only to the specified power type and ensure a good ground connection. An isolation transformer should always be used when working on any mains power supply unit. The correct power cord, as supplied with the equipment, must be used, and the ground connection should never be tampered with. Fuses must always be replaced with the correct type and rating. When opening the unit, the mains power cord must be switched off and removed. All power supply covers and safety shields must be in place before applying power for diagnostic fault finding.
The manual also provides guidance on closing the unit, stressing the importance of checking the quality and accuracy of the service work, removing any dirt or debris, and ensuring all assemblies, harnesses, and connectors are correctly aligned and plugged in. Jumper settings and control configurations must be correctly set according to customer requirements. Testing the unit after service is critical to ensure that the repair work has been successfully carried out and that the equipment operates according to the Important Safety Instructions in the user guide. For shipping, adequate packing, such as the original packaging or a purpose-designed flight case, is recommended to prevent damage.
Fault finding is facilitated by tracing the signal flow through the circuit path, with reference to the system block diagram. Replacement circuit assemblies are available from Allen & Heath. The manual includes detailed parts identification, categorizing components into exterior and interior parts. Exterior parts include various knobs (red, blue, black, grey), fader knobs (grey, blue, black, red), switch caps (rectangle black, white, grey; square grey; round grey), plastic side moldings (left and right), nut pots, and feet. Interior parts are identified by their specific circuit board assemblies, such as the PSU (Power Supply Unit), mono-R meter, stereo I/P (input), mono I/P, master out, master right, master left, distribution, and group boards (Group 1, Group 2, Group 3, Group 4 USB). The fan and various screws (for XLR, front panel, fader, side molding, and base) are also listed. Instructions on how to order parts are provided, directing users to their local distributor or an appointed A&H dealer/service center in the UK.
Development changes are noted as ongoing factory implementations that are not critical to the basic function of the unit, leaving the decision to update a unit with these changes to the owner or service engineer. This comprehensive approach ensures that the ZED 4 bus mixers can be effectively maintained and repaired, extending their operational lifespan and ensuring continued high performance.
General| Type | Analog |
|---|---|
| Channels | 28 |
| Mic Inputs | 8 |
| Line Inputs | 16 |
| Stereo Inputs | 4 |
| Aux Sends | 6 |
| Subgroup Outs | 4 |
| Matrix Outs | 2 |
| Faders | 100mm |
| USB | No |
| Phantom Power | Yes |
| Effects | No |
| Headphone Output | Yes |
| Monitor Outputs | 2 |
| Weight | 12.5 lbs |
| EQ Bands | 3-band |
