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9BSST FIVE CHANNEL POWER AMPLIFIER
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Front Panel
1. 'SST POWER' switch
The front panel label 'ST POWER', is a touch sensitive membrane switch used to apply or remove A/C line power to the
9BSST circuitry. Push firmly the center of the switch until the power-up sequence begins. Push again and the 9BSST will
power-down. ( Note: the rear circuit breaker must be on for the 9BSST to power-up)
2. LED Indicators
Each 9BSST channel has a LED indicator to monitor the following conditions:
Unlit - indicates channel has no power.
Red - indicates channel is muted (power-up-down sequence)
GReen - indicates channel operation is normal.
FlashinG Red - indicates channel clipping.
ORanGe - indicates channel thermal shutdown.
Power up sequence
After pushing the 'SST POWER' switch, each channel led will turn from unlit to red (mute). When the power supplies
have stabilized the channel will come out of mute and the led will change to green (normal operation).
Unlit led ( No power )
The 9BSST channel led when unlit indicates no A/C mains power is present at the channel. If all channel led indicators
are unlit the 9BSST probably needs only to be powered on. A single led not lighting possibly indicates blown channel
fuses.
When checking fuses switch off the circuit breaker on the rear panel, or unplug the power cord. Use only the specified
quick-acting 4 amp 250V 5mm x 20mm fuses. See page 6 for the fuse locations.
Clipping ( flashing red )
Clipping occurs when the channel output level no longer can follow the level increase at the input (Over driven input con-
dition). When a 9BSST channel is driven into clipping the channel led will change from green to red then back to green
when the level is reduced ( Flashing Red ). Momentary clipping can be tolerated, however it indicates that maximum un-
distorted power has been surpassed and potential speaker damage may result if overload conditions persist. Any ampli-
fier that is constantly operated into clipping indicates a more powerful amplifier is needed for that application.
Thermal Shutdown ( orange )
The 9BSST channel has thermal shutdown circuitry to prevent damage due to overheating.
Should thermal shutdown occur, the channel will mute, and the channel led will turn orange indicating this condition.
When the channel has cooled to a safe operating condition the channel will return to normal operation.
Persistent Thermal shutdown indicates steps need to be taken to increase airflow across the channel or channels heat
sink. ( Also see installation section on ventilation ).
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