Bose FREESPACE 4400, Service Manual

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9. Short Circuit Protection Test
9.1 Connect a 2 ohm, 250 Watt load resistor to the Zone 1 output.
9.2 Apply a 1 kHz, -18 dBV (126 mV) signal into the Direct Input connector pins 1, 2 and 3.
Connect the plus side to pin 1 (+). Connect the minus side to pins 2 (-) and 3 (GND).
9.3 Verify that the amplifier goes into Protect mode.
Note: When the amplifier goes into protect mode the speakers are immediately disconnected,
and the amplifier is shut down for approximately 3.5 seconds. It is then restarted and checked
again after a 1 second stabilization period. If everything is not OK, 6 more off-wait-stabilize-reset
cycles are attempted. If after 6 retries within 1 minute, everything is still not OK, the amplifier is
returned to a state that requires a “Standby-On” cycle, a “hard power down” or some other form
of user intervention to restart.
9.4 Repeat steps 9.1 to 9.3 for the Zone 2, 3 and 4 outputs.
10. Code Revision Level Check
This test displays the code revision levels for the various microcontrollers used in the 4400
amplifier. This will tell the repair technician whether or not he needs to update the code before
returning the unit.
10.1 Launch the Bose ® Installer TM software, if not already open. Click on the “Service Hardware”
tab and read the installed code revision levels for:
Host Microcode, DSP code, Peripheral PIC code, Lower Amplifier PIC code, & Upper Amplifier
PIC code.
10.2 Update code revision levels as needed. Refer to the appendix of this service manual for
update procedures.
11. Input Default Configuration
Reset the unit to the default settings by completing the steps below. This will ensure that the unit
is in the proper state when installed after a repair.
11.1 With the unit in STANDBY or ON status, launch the Installer software.
11.2 Verify the following factory default settings; Line 1A and 1B Inputs mapped to Zone 1,
Zone 2, Zone 3 and Zone 4 outputs.
11.3 Save settings to flash memory. Power down the unit once the flash update is complete.
TEST PROCEDURE