Page 1
2
CONTENTS
Safety Information ............................................................................................................................. 3
Warranty ............................................................................................................................................. 4
Product Description .......................................................................................................................... 4
Specifications .............................................................................................................................. 5-10
Electrostatic Discharge Sensitive (ESDS) Device Handling ....................................................... 11
Part List Notes ................................................................................................................................. 11
Product Variations .......................................................................................................................... 11
Accessories..................................................................................................................................... 12
Packaging Part List, FreeSpace
® 4400 System ............................................................................ 13
Figure 1. FreeSpace 4400 System Packaging View .........................................................................13
Packaging Part List, Rack Ear / Connector Kit ............................................................................ 14
Figure 2. Rack Ear / Connector Kit Packaging View ........................................................................14
Main Part List, FreeSpace Model 4400 Amplifier ................................................................... 15-16
Figure 3. FreeSpace Model 4400 Business Music System Exploded View ......................................16
Electrical Part Lists ................................................................................................................... 17-59
Front Panel PCB Assembly ...................................................................................................... 17-18
Digital Signal Processor PCB Assembly ................................................................................ 19-33
Digital Signal Processor Flash Memory PCB Assembly ............................................................. 33
Mic Sense PCB Assembly ........................................................................................................ 34-38
Power Supply / Power Amplifier PCB Assembly .................................................................... 39-56
Power Amplifier Driver PCB Assembly ................................................................................... 57-59
Disassembly Procedures .........................................................................................................60-62
Test Procedure Setup ..................................................................................................................... 63
Test Procedures ........................................................................................................................ 64-67
Troubleshooting ........................................................................................................................ 68-75
Theory of Operation .................................................................................................................. 76-83
Microcontroller Code Update Procedure ...................................................................................... 84
Circuit Board Layout Diagrams ............................................................................................... 85-93
Figure 4. Mic Sense PCB Top Etch Board Layout Diagram ..............................................................85
Figure 5. Mic Sense PCB Bottom Etch Board Layout Diagram ........................................................85
Figure 6. Flash Memory PCB Top Etch Board Layout Diagram ........................................................85
Figure 7. Flash Memory PCB Bottom Etch Board Layout Diagram ..................................................85
Figure 8. Wallplate Sense PCB Top Etch Board Layout Diagram ....................................................86
Figure 9. Wallplate Sense PCB Bottom Etch Board Layout Diagram ...............................................86
Figure 10. AC Power Selector PCB Top Etch Board Layout Diagram ..............................................86
Figure 11. AC Power Selector PCB Bottom Etch Board Layout Diagram .........................................86
Figure 12. DSP PCB Top Etch Board Layout Diagram .....................................................................87
Figure 13. DSP PCB Bottom Etch Board Layout Diagram ...............................................................88
Figure 14. Front Panel PCB Top Etch Board Layout Diagram ..........................................................89
Figure 15. Front Panel PCB Bottom Etch Board Layout Diagram ....................................................89
Figure 16. TriPath Module PCB Top Etch Board Layout Diagram ....................................................89
Figure 17. TriPath Module PCB Bottom Etch Board Layout Diagram ..............................................89
Figure 18. Amplifier Upper PCB Top Etch Board Layout Diagram ....................................................90
Figure 19. Amplifier Upper PCB Bottom Etch Board Layout Diagram ..............................................91
Figure 20. Amplifier/Power Supply Lower PCB Top Etch Board Layout Diagram .............................92
Figure 21. Amplifier/Power Supply Lower PCB Bottom Etch Board Layout Diagram .......................93
Integrated Circuit Diagrams ................................................................................................... 94-105
Service Manual Revision History ................................................................................................. 106
Page 2
3
SAFETY INFORMATION
CAUTION: The Bose ® FreeSpace ® 4400 Business Music System
contains no user-serviceable parts. To prevent warranty infractions,
refer servicing to warranty service stations or factory service.
PROPRIETARY INFORMATION
THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION OF
BOSE CORPORATION WHICH IS BEING FURNISHED ONLY FOR
THE PURPOSE OF SERVICING THE IDENTIFIED BOSE PRODUCT
BY AN AUTHORIZED BOSE SERVICE CENTER OR OWNER OF
THE BOSE PRODUCT, AND SHALL NOT BE REPRODUCED OR
USED FOR ANY OTHER PURPOSE.
1. Parts that have special safety characteristics are identified by the symbol on schematics
or by special notes on the parts list. Use only replacement parts that have critical characteristics
recommended by the manufacturer.
2. Make leakage current or resistance measurements to determine that exposed parts are
acceptably insulated from the supply circuit before returning the unit to the customer.
Use the following checks to perform these measurements:
A. Leakage Current Hot Check-With the unit completely reassembled, plug the AC line cord
directly into a 120V AC outlet. (Do not use an isolation transformer during this test.) Use a
leakage current tester or a metering system that complies with American National Standards
Institute (ANSI) C101.1 "Leakage Current for Appliances" and Underwriters Laboratories (UL)
UL6500 / UL60065 / IEC 60065 paragraph 9.1.1. With the unit AC switch first in the ON position
and then in OFF position, measure from a known earth ground (metal waterpipe, conduit, etc.)
to all exposed metal parts of the unit (antennas, handle bracket, metal cabinet, screwheads,
metallic overlays, control shafts, etc.), especially any exposed metal parts that offer an electrical
return path to the chassis. Any current measured must not exceed 0.5 milliamp. Reverse the
unit power cord plug in the outlet and repeat test. ANY MEASUREMENTS NOT WITHIN THE
LIMITS SPECIFIED HEREIN INDICATE A POTENTIAL SHOCK HAZARD THAT MUST BE
ELIMINATED BEFORE RETURNING THE UNIT TO THE CUSTOMER.
B. Insulation Resistance Test Cold Check-(1) Unplug the power supply and connect a jumper
wire between the two prongs of the plug. (2) Turn on the power switch of the unit. (3) Measure
the resistance with an ohmmeter between the jumpered AC plug and each exposed metallic
cabinet part on the unit. When testing 3 wire products, the resistance measured to the product
enclosure should be between 2 and infinite MOhms. Also, the resistance measured to exposed
input/output connectors should be between 4 and infinite MOhms. When testing 2 wire prod-
ucts, the resistance measured to exposed input/output connectors should be between 4 and
infinite MOhms. If it is not within the limits specified, there is the possibility of a shock hazard,
and the unit must be repaired and rechecked before it is returned to the customer.
CAUTION
Danger of explosion if battery is incorrectly replaced.
Replace only with the same or equivalent type.
