Test E: No Sound From All Speakers - THX(R) Audio System
PINPOINT TEST E: NO SOUND FROM ALL SPEAKERS - THX(R) AUDIO SYSTEMNormal Operation
The audio control module (ACM) enables the audio digital signal processing (DSP) module through circuit CME31 (BU/GN). The DSP module receives voltage through circuits SBP38 (BN/RD) and SBP40 (VT/RD), and ground through circuit GD114 BK/BU).
Left and right channel audio signals are sent from the ACM to the DSP module through circuits VME07 (WH), RME07 (WH/BN), VME10 WH/VT), and RME10 (WH/OG). If there is a fault on one of these circuits, the audio quality will be reduced by approximately 25% for all speakers.
To enable the DSP module, the ACM sends voltage through the enable/clip circuit CME31 (BU/GN). The circuit acts as both an output (to enable the amplifier) and an input (to detect an amplifier overload condition). A variable resistor in the DSP module modifies the voltage signal from the ACM. In the event of an overload, the ACM clips the audio output signal to the amplifier (heard as distortion), in order to prevent damage to the amplifier and speakers.
The clip/enable status is based on the following voltages, as detected by the ACM:
- Less than 0.4 volts: amplifier disabled
- Between 3.8 and 6.7 volts: amplifier enabled
- Greater than 8.5 volts: amplifier clipped
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- DSP module
- ACM
E1-E4:
E4-E7:
E7-E9:
