Faultfinding Notes, Replacing Components

FAULTFINDING NOTES.

+/- 17V RAILS.

If one side of the +/-17V supply is not working, the mutual shutdown system will close down both sides of the supply. This makes faultfinding difficult as it is often not obvious which side has failed. The mutual shutdown can be disabled by linking pins 4 and 5 on BOTH opto-isolators

IT IS ESSENTIAL THAT THIS IS REMOVED AFTER SERVICING IS COMPLETED! FAILURE TO DO THIS MAY CAUSE SEVERE CONSOLE DAMAGE IF ONLY ONE 17V RAIL SHUTS DOWN.

If there is no power to the 723 IC (eg if R1 or R2 is open- circuit) the output will remain low, but no damage occurs.

+8V SUPPLY.

This is a completely standard IC regulator circuit. The regulator REG3 is the only part that is likely to fail.

REPLACING COMPONENTS

Replacement of any components should be undertaken only after switching the power supply unit OFF and disconnecting the mains supply lead from the power supply unit.

Replacement of any of the fuses in the power supply units is possible without the removal of the circuit board.

The fuses are held in open fuseholders on the top of the board. These can be carefully removed by hand. Ensure that the insulating fuse covers are replaced with the new fuses.

Various components are mounted along the heatsink extrusion. The extrusion/pcb assembly must be removed from the case to gain access to the underside of the pcb in order to unsolder and/or undo the appropriate component. They can be removed by desoldering the pins, where appropriate, and unscrewing the fixing nuts or the fixing screws, taking care to retain the small insulating bush(es).

Retain carefully the mounting pads and plastic insulating bushes where fitted.

THESE MUST BE CORRECTLY REFITTED TO AVOID DAMAGE TO THE UNIT.

The correct high efficiency mounting pad must be used, and this should be replaced if it appears to be damaged (see the Parts Lists for the relevant Soundcraft Part Numbers). When refixing or replacing the device, it is important to screw the device down before resoldering the pins to avoid stressing the pads on the circuit board.

NOTE : The heatsink bracket is earthed through its mechanical contact with the rest of the chassis and so a faulty mounting pad may cause the output of its regulator to be connected to earth.

Take care not to bend the pins on the regulators, or to strain the corresponding pads on the circuit board

18	Technical Description

CPS250, CPS275 specifications

SoundCraft is renowned for producing high-quality audio mixing consoles that cater to a wide range of audio professionals and enthusiasts. Among their notable offerings are the SoundCraft CPS275 and CPS250 power amplifiers, which combine innovative technologies with reliable performance.

The SoundCraft CPS275 is a powerhouse designed to deliver a robust output with exceptional clarity. It features a dual-channel configuration, providing 275 watts per channel into 4 ohms. The CPS275 is built with a solid-state design, ensuring high efficiency and minimal distortion, making it suitable for both live performances and studio applications. One of its distinguishing features is the advanced thermal protection system, which safeguards the amplifier from overheating, ensuring longevity and reliability even in demanding environments.

On the other hand, the SoundCraft CPS250 is a slightly smaller model, ideal for users seeking a balance between power and portability. It offers 250 watts per channel into 4 ohms, making it perfect for smaller venues or monitors. This model emphasizes versatility and sound fidelity, featuring a class AB circuitry that enhances audio accuracy while maintaining low noise levels.

Both the CPS275 and CPS250 come equipped with comprehensive protection circuitry, which includes short-circuit, overload, and DC protection. This guarantees that both amplifiers will perform consistently without risking damage to connected equipment.

In terms of connectivity, these amplifiers feature XLR and 1/4-inch TRS inputs, allowing seamless integration with a wide array of sound systems. Additionally, the CPS series employs efficient cooling systems, ensuring optimal performance without the risk of overheating even during prolonged usage.

Both models are designed with rugged construction, making them suitable for the rigors of touring and live events. They are equipped with rack-mountable chassis, allowing for easy installation in professional setups.

Overall, the SoundCraft CPS275 and CPS250 amplifiers exemplify the brand's commitment to delivering high-quality audio solutions. With their advanced technologies, protective features, and exceptional sound quality, they cater to a variety of audio applications, making them an excellent choice for professionals in the music and live sound industries. Whether powering large PA systems or smaller setups, these amplifiers are engineered to meet the demands of any audio environment with impressive accuracy and reliability.