SA-GX370 Chipset

The main power amplifier IC in the SA-GX370 is the SVI3204 module, where each module provides two power output channels. Therefore two of these are used in a surround sound system, where one module manages the front channels and another module manages the rear channels. The SVI3204 modules operate on a split-rail power supply of ±28 V at pins 5 and 4. The audio output is at pin 3 and pin 6 and the voltages there should read 0 V when there is no input signal to the amplifier. Usually a shorted module will show high voltages close to supply rails through these pins. The protection circuitry prevents these high voltages passing to the speakers, as it would destroy them. The protect circuitry usually consists of an output relay which when engaged connects the speaker terminals to pins 3 and 6. A microcontroller usually runs an algorithm to determine if it is safe to engage this relay. It does so by receiving information regarding the voltage levels at pins 3 and 6 to determine whether the SVI3204 is operating within established parameters. If the DC voltages are abnormally high, then it goes into protect mode and displays "OVERLOAD".

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