23
TROUBLE SHOOTING
AMPLIFIER ACTIVATES THE PROTECTIVE CIRCUIT / THE PROTECT LED ILLUMINATES
Check the following steps:
Short circuit on the speaker cables
• First disconnect all speaker cables from the amplifier. Use a multimeter to check the ohmic impedance of each
loudspeaker by measuring between its plus and minus lines. With standard loudspeakers the value fluctuates
between 3 and 5 ohms. The values for low-resistance subwoofers can be lower.
• The measurement shows a resistance value of less than 0.5 Ohms
Then there is a short circuit. Remove the wiring of the affected loudspeaker at its connections. Now use the
multimeter to check the ohmic impedance directly at the loudspeaker connections by measuring between the
plus and minus connections.
The measurement shows a resistance value of more than 0.5 Ohms
• The speaker is fine, so the speaker wire appears to be defective and causing a short circuit.
Replace the defective speaker cable.
The measurement shows a resistance value of less than 0.5 Ohms
• The speaker appears to be defective and is shorting out. Replace the defective speaker.
The load impedance of the loudspeakers or the subwoofer is too low
• Compare the ohmic impedance of the connected loudspeaker or subwoofer with the technical specifications of the
amplifier. For example, if the amplifier is only designed for 2 or 4 ohm operation, no loudspeaker with less than 2
ohms may be connected.
The cross-section of the power cables is too small
• If the cable cross-section is too small, this leads to an increased ohmic resistance and thus to a voltage drop (volt-
age loss). This indicates that the amplifier consumes more power. The increased power consumption results in a
significantly higher heat development and the amplifier switches to thermal protection mode. Therefore, observe
the recommended cable cross-sections in these instructions and, if necessary, lay power cables with a larger
cable cross-section.
The amplifier is overheated
• The heat sink of each amplifier requires sufficient air circulation to be able to dissipate the heat generated during
operation. If necessary, change the installation position in favor of better cooling of the amplifier or ensure better
air circulation at the installation location.
• Turn off the sound system and wait about half an hour for the amplifier to cool down again. With very hot outside
temperatures and strong sunlight, enormous heat develops inside the vehicle. The amplifier then activates its
thermal protection circuit to prevent damage. After cooling down, the amplifier works properly again.
All instructions in this troubleshooting refer to the entire sound system and its individual components. The
features of your device may not match the functions described in the notes. Then skip this point and move
on to the next one.
NOTE
Summary of Contents for QS-TWO
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