SRS Labs SR560 manual Calibration and Repair, Offset Adjustment, Front END Replacement

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CALIBRATION AND REPAIR

OFFSET ADJUSTMENT

The SR560's front-panel offset adjustment provides an easy way for the user to null the amplifier's DC offset. Use the COUPLING pushbutton to light the GND LED. Now, regardless of the SOURCE setting, the input to the amplifier is grounded internally. Insert a small screwdriver through the front- panel OFFSET hole and adjust the offset potentiometer until the DC offset of the amplifier (e.g. as viewed on a DVM) is zero. Finally, return to the desired coupling.

CALIBRATION

There are four pots, which are used to calibrate the instrument. The pots adjust the front-end CMRR (Common Mode Rejection Ratio) and offset. These pots are located close to the front of the instrument, and may be accessed by removing the bottom cover.

These pots should be adjusted to optimize the CMRR or null the offset when the front- end FET is replaced. Two of the pots adjust the CMRR and offset when the front-end gain is x10, and two adjust the CMRR and offset when the front-end gain is x2. The x10 gain pots must be set first, followed by the x2 gain pots.

First, the front panel offset pot must be set to zero:

•Adjust front panel Offset pot to read 0 VDC on pin 14, U407.

Next adjust the offset and CMRR for the case where the front-end gain is x10. View the amplifier output on a scope and perform the following adjustments:

•Couple = GND, Gain = 5 k, LOW NOISE: adjust P103 to null DC and output.

Now use a function generator as the source of a common mode signal:

•Apply 1 kHz 1 Vpp sine to both the A and B inputs.

•Couple = DC, source = A - B: adjust P102 to null sine wave output.

Now adjust the offset and CMRR for the case where the front-end gain is x2. View the amplifier output on a scope and perform the following adjustments:

•Couple = GND (remove signal from A and B inputs), Gain = 5 k, HIGH DR: adjust P104 to null DC and output.

•Apply 1 kHz 1 Vpp sine to both the A and B inputs.

•Couple = DC, source = A - B: adjust P101 to null sine wave output.

NOTE: In the above procedures, the gain of the front-end (x10 or x2) is determined by the selection of LOW NOISE or HIGH DYNAMIC RESERVE.

FRONT END REPLACEMENT

The most commonly damaged component is the front-end FET (U106, National Semiconductor Corp. P/N NPD5564). It is located in an 8-pin DIP socket behind the relays near the input BNCs. If the instrument exhibits a constant overload, excessive drift or noise, or large input bias currents, it is likely that this component has been damaged.

When replacing the FET, be certain that all eight pins are inserted into the socket, and observe the orientation of pin #1. After replacement adjust the CMRR and offset per the calibration procedure. More severely damaged front-ends may require replacement of op-amp, U102.

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Contents Model SR560 Page Table of Contents Calibration and Repair PCB SR560 Revision F 9/89 SchematicsAppendix a Appendix BInstrument Overview Introduction and SetupPreparation for USE Repackaging for Shipment Accessories FurnishedUse in Biomedical Applications Environmental ConditionsPage SR560 LOW-NOISE Preamplifier Specifications Chart SpecificationsSpecifications Operation and Controls PowerFront Panel Operating Summary SourceFilters Reset Gain ModeGain OutputAmplifier Power Output AC Power InputBattery Charger Rear Panel Operating SummaryBattery Care Battery Care and UsageBlanking Input RS-232 InterfaceAvoid Deep Discharge Circuit Description Configurable Filters and GainDifferential LOW-NOISE Front END Output StagesBattery Charger and PRE-REGULATORS Overload DetectionMicroprocessor Rear Panel Interfaces Power RegulatorsFront Panel Batteries and P.E.MFront END Replacement Offset AdjustmentCalibration and Repair CalibrationSR560 Offset Adjustment Procedure Battery ReplacementFuse Replacement Noise Contours Dynamic Reserve Input Voltage NoiseMaximum Calibration and Repair Appendix a CommandsRemote Programming IntroductionAppendix a Noise Sources and Cures Appendix BIntrinsic Noise Sources Non-Essential Noise SourcesInductive Coupling Capacitive CouplingResistive Coupling or ‘Ground Loops’ MicrophonicsThermocouple Effect Appendix B Front Panel Parts List SR560 Component Parts ListMain Board Parts List 22U MIN 01U Axial 804 00225-548 Insl MTP5N05 SR560 Component Parts List SR560 Component Parts List PIN Mach SR566 Assy Adhes Tape Miscellaneous Parts List SR560 Component Parts List

SR560 specifications

SRS Labs SR560 is a cutting-edge audio enhancement technology that has gained recognition for its ability to deliver an immersive sound experience. Built upon years of research, the SR560 utilizes proprietary algorithms to achieve high-fidelity sound output while maintaining an incredibly dynamic range.

One of the most notable features of the SR560 is its adaptive audio processing, which adjusts sound dynamics based on the content being played. This means that whether one is listening to music, watching a movie, or playing video games, the sound quality is optimized in real-time to provide the best listening experience. The SR560 excels at enhancing dialogue clarity in films, ensuring that important audio elements are never lost amidst background sounds.

Another key characteristic of the SR560 is its support for multi-channel audio. With the rise of surround sound systems, the SR560 is designed to integrate seamlessly with 5.1 and 7.1 speaker setups. This ensures that users can enjoy a true surround sound experience, where each audio channel is processed independently to create a lifelike auditory environment. The SR560’s processing capabilities allow it to convert standard stereo audio into multi-channel output, enriching the listening experience for any audio format.

SRS Labs has equipped the SR560 with advanced bass optimization technology. This feature enhances low-frequency sound, providing deep, rich bass without distortion. Whether it’s the thumping beats of music or the rumble of action-packed movies, the SR560 ensures that users can experience the full spectrum of audio without compromising on quality.

Furthermore, the SR560 showcases state-of-the-art sound management features that provide users with customizable audio profiles. This allows users to tailor their audio experience according to personal preferences, whether they prefer a more balanced sound, enhanced bass, or boosted treble frequencies. The intuitive interface ensures that adjustments can be made effortlessly.

In conclusion, the SRS Labs SR560 stands out as a versatile audio enhancement technology that caters to the needs of various audio consumers. By combining adaptive processing, multi-channel support, bass optimization, and customizable profiles, the SR560 ensures a rich and immersive audio experience. As the demand for high-quality sound continues to rise, the SR560 is poised to remain a significant player in the evolution of audio technology.
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