BOSE 266614R00 Schematic
Contents
Safety Information.............................................................................................................................2
Electrostatic Discharge Sensitive (ESDS) ......................................................................................3
Device Handling ................................................................................................................................3
Warranty Information........................................................................................................................3
Specifications................................................................................................................................ 4-9
Theory of Operation.................................................................................................................. 10-16
Disassembly/Assembly Procedures ....................................................................................... 17-19
Figure 1. Amp PCB and Heat Sink Assembly .................................................................................19
Test Procedure Setup .....................................................................................................................20
Test Procedures ........................................................................................................................ 21-23
Part List Notes.................................................................................................................................24
Figure 2. E-4 Exploded View...........................................................................................................25
Main Part List ..................................................................................................................................26
Electrical Part List..................................................................................................................... 27-60
Packaging Part List .........................................................................................................................61
Figure 3. Packaging Exploded View................................................................................................61
IC Pin Out Diagrams ................................................................................................................. 62-68
Appendix .................................................................................................................................... 69-72
PROPRIETARY INFORMATION
THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION OF
BOSE
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.
®
CORPORATION WHICH IS BEING FURNISHED ONLY FOR
1
SAFETY INFORMATION
1. Parts that have special safety characteristics are identified by the symbol on schemat-
ics 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)
6500 / IEC 60056 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 water pipe, 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 products, the resistance measured to exposed input/output connectors should be between
4 and infinite M Ohms. When testing 2 wire products, the resistance measured to exposed
input/output connectors should be between 4 and infinite M Ohms.
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 OR
MISTREATED. REPLACE ONLY WITH THE SAME OR EQUIVALENT TYPE. DO NOT RECHARGE, DISASSEMBLE OR DISPOSE OF IN FIRE.
Replace battery with Panasonic part number BR2325 only. Use of another battery
may present a risk of fire or explosion.
2
ELECTROSTATIC DISCHARGE SENSITIVE (ESDS)
DEVICE HANDLING
This unit contains ESDS devices. We recommend the following precautions when repairing,
replacing, or transporting ESDS devices:
• Perform work at an electrically grounded work station.
• Wear wrist straps that connect to the station or heel straps that connect to conductive floor
mats.
• Avoid touching the leads or contacts of ESDS devices or PC boards even if properly
grounded. Handle boards by the edges only.
• Transport or store ESDS devices in ESD protective bags, bins, or totes. Do not insert unprotected devices into materials such as plastic, polystyrene foam, clear plastic bags, bubble wrap
or plastic trays.
CAUTION: THE BOSE® FREESPACE® MODEL E-4 BUSINESS MUSIC SYSTEM CONTAINS
NO USER-SERVICEABLE PARTS. TO PREVENT WARRANTY INFRACTIONS,
REFER SERVICING TO WARRANTY SERVICE STATIONS OR FACTORY SERVICE.
Warranty Information
The Bose FreeSpace Model E-4 Business Music System is covered by a transferable 1-year
limited warranty.
3
SPECIFICATIONS
Audio input connectors:
Source 2
Page balanced 4 pin Beau style: +, -, ground and contact closure in
Aux/Mic/Line 3 pin Beau style, +, - and ground
Mic 1-4 3 pin Beau style, +, - and ground
Direct In 4 pin Beau style, +, -, ground, and contact closure in
Audio output
connectors:
MOH out unbalanced RCA, + and Ground
Amp 1-4 2 pin, Beau style, contact closure in and ground
Control connectors:
Standby In 2 pin Beau style, contact closure in and ground
Dimensions:
Weight:
AC Mains input:
Overall performance
Gain:
Dynamic range:
THD+N:
Crosstalk at 1 kHz:
Crosstalk at 10 kHz:
Frequency response:
Output noise:
Output noise
character:
Source 1
Line out
Remote 1-4 mini Din, 8 pin, ground shell
5.25"H x 16.5"W x 15.5"D (13.3 x 43.8 x 39.4 cm)
30 lbs. (13.6 kg)
IEC standard
3 pin
receptacle
Nominal Limits Conditions
0 dB +
100 dB >=96 dB measured with ADC/DAC full scale mapped to
.05% .1% at +10 Vrms output, for signal frequencies from
-80 dB <= -70 dB
-60 dB <= -50 dB
30-20 kHz +
-70 dBV <= -65 dBV channel noise measured through an A weighting
unbalanced RCA, shell is grounded through a 301Ω resistor
unbalanced RCA, shell is grounded through a 301Ω resistor
4 pin Beau style, +, -, ground, and contact closure in
user selectable 120V to 240V
1 dB at 1 kHz; input gain set to nominal 0 dB
+ 17 dBV; this is THD +N measured at FS-60,
through A weighting filter, and expressed in dB
below full scale.
30 Hz to 20 kHz
terminate unused input terminals with 100Ω
balanced-connected resistors.
terminate unused input terminals with 100Ω
balanced-connected resistors.
3 dB reference 1 kHz, measured at 0 dBV input
filter. Gain structure set to deliver rated power
and expressed in dBV
as monitored by a listener, must be free of
audible tones, whistles, birdies, demodulated RF,
TV “60 Hz” sync signal, buzz, etc.
4
SPECIFICATIONS
Line Input Source 1 and 2
Nominal Limits Conditions
Source impedance:
Input impedance
differential:
CMRR referred to
output:
Input sensitivity for
codec FS:
Gain, all settings: 20 dB to
Maximum input level: +17 dBV > =+17 dBV THD+N <=0.3%, 30-20 kHz, 0 dB gain
THD+N: .001% .01% at +10 dBV output, 1 kHz, 20 dB gain
Crosstalk at 1 kHz: -90 dB <=-80 dB
Crosstalk at 10 kHz: -70 dB <=-60 dB
Frequency response: 30 to 20 kHz +
Page and Aux/Mic Inputs
Nominal Limits Conditions
Source impedance:
Input impedance
differential:
Equivalent input noise
at INA129 gains of 60
dB, 40 dB, 20 dB and
0 dB:
200Ω 10 to 2 kΩ
+> 50 kΩ
80 dB
-20 dBV to
+17 dBV
-20 dB
200Ω 10 to 2 kΩ
20 kΩ
at 60 dB,
-130 dBV
at 40 dB,
-127 dBV
at 20 dB,
-115 dBV
at 0 dB,
-96 dBV
+
20%
>= 74 dB
1 dB
+
1 dB
+
1.5 dB reference 1 kHz, measured at 20 dB gain and
5%
+
at 60 dB,
-127 dBV
at 40 dB,
-125 dBV
at 20 dB,
-113 dBV
at 0 dB,
-93 dBV
frequency response specification maintained with
sources over this range
at 1 kHz
at 1 kHz, 20 dB gain, 200Ω source impedance
at 1 kHz
1 kHz, 50Ω source
with 0 dBV output
frequency response specification maintained with
sources over this range
at 1 kHz
A weighted RMS, 200Ω source termination
5
SPECIFICATIONS
Page and Aux/Mic Inputs (continued)
Nominal Limits Conditions
CMRR referred to
output:
Input sensitivity for
codec FS:
Gain, all settings:
Maximum input level: +17 dBV > =10 dBV THD+N <=0.3%, 20-20 kHz, 0 dB gain
THD+N: .001% .01% at +10 dBV output, 1 kHz, 60 dB gain
Crosstalk at 1 kHz: -90 dB <=-80 dB
Crosstalk at 10 kHz: -70 dB <=-60 dB
Frequency response: 30 to 20 kHz +0/-0.5 dB Reference 1 kHz, measured at 60 dB gain and
Sense Mic Inputs
Nominal Limits Conditions
Source impedance:
Input impedance
differential:
Equivalent input noise
at INA129 gains of 60
dB, 40 dB, 20 dB and
0 dB:
CMRR referred to
output:
Phantom power: +12V +
Input sensitivity for
codec FS:
Gain, all settings: -60 dB to
90 dB
-60 dBV to
+17 dBV
20 dB to
–20 dB
200Ω 10 to 2 kΩ
20 kΩ
at 60 dB,
-127 dBV
at 40 dB,
-115 dBV
at 20 dB,
-96 dBV
90 dB
-60 dBV to
+20 dBV
+20 dB
>= 70 dB
1 dB
+
1 dB
+
5%
+
at 60 dB,
-125 dBV
at 40 dB,
-112 dBV
at 20 dB,
-93 dBV
>= 60 dB
1V open circuit
1 dB
+
1 dB
+
at 1 kHz, 60 dB gain, from source of nominal
200Ω
at 1 kHz
1 kHz, 50Ω source
with 0 dBV output
frequency response specification maintained with
sources over this range
at 1 kHz
A weighted RMS, 200Ω source termination
at 1 kHz, 60 dB gain, from source of nominal
200Ω
at 1 kHz
1 kHz, 50Ω source
6
SPECIFICATIONS
Sense Mic Inputs (continued)
Nominal Limits Conditions
Maximum input level: +10 dBV > =7 dBV THD+N <=0.3%, 20-20 kHz, 0 dB gain
THD+N: -84 dB <=-80 dB at +10 dBV output, 1 kHz, 60 dB gain
Crosstalk at 1 kHz: -90 dB <=-80 dB
Crossalk at 10 kHz: -70 dB <=-60 dB
Frequency response: 20 to 20 kHz +0/-0.5 dB reference 1 kHz, measured at 60 dB gain and
with 0 dBV output
Direct Input
Nominal Limits Conditions
Source impedance:
Input impedance
differential:
CMRR referred to
output:
Input sensitivity for
codec FS:
Gain: 0 dB +
Maximum input level: +17 dBV > =+17 dBV THD+N <=0.3%, 30-20 kHz, 0 dB gain
THD+N: .001% .01% at +10 dBV output, 1 kHz, 20 dB gain
Crosstalk at 1 kHz: -90 dB <=-80 dB
Crosstalk at 10 kHz: -70 dB <=-60 dB
Frequency response: 30 to 20 kHz +0/-0.5 dB reference 1 kHz, measured at 20 dB gain and
200Ω 10 t0 2 kΩ
20%
+> 10 kΩ
92 dB
-20 dBV to
+17 dBV
+
>= 60 dB
1 dB
+
1 dB from input connector to amplifier input stage
Line Output
Nominal Limits Conditions
Output impedance:
Maximum output
level:
200Ω
+17 dBV
1% impedance at 1 kHz, each output terminal
+
>=+17 dBV
frequency response specification maintained with
sources over this range
at 1 kHz
at 1 kHz, 20 dB gain, 200Ω source impedance
at 1 kHz
with 0 dBV output
1 kHz, THD less than 0.1%, load 10 kΩ,
differential
7
SPECIFICATIONS
Line Outputs (continued)
Nominal Limits Conditions
CMRR referred to
output:
Output noise: -90 dBV <=-85 dBV A weighted, set for 0 dB gain
THD+N: .001% .01% at +10 dBV output, 1 kHz, 20 dB gain
Crosstalk at 1 kHz: -90 dB <=-80 dB set for 0 dB gain, no limiting, terminate the
Crossalk at 10 kHz: -70 dB <=-60 dB
Frequency response: 30 to 20 kHz +0/-1.0 dB reference 1 kHz, measured at 20 dB gain and
Turn on/off pop: 10 mV peak <=+
92 dB
>= 60 dB
50 mV
peak
at 1 kHz, 20 dB gain, 200Ω source impedance
unused input with a 50 Ω resistor
with 0 dBV output
as monitored by a listener, set for maximum gain,
with an 802
audible, must be a muffled thud or thump, not a
pop, click or static.
loudspeaker 3 feet from listener, if
Music on Hold (MOH)
Nominal Limits Conditions
Output impedance:
Maximum output
level:
Output noise: -90 dBV <=-85 dBV A weighted, set for 0 dB gain
THD+N: .001% .01% at +17 dBV output, 1 kHz, 0 dB gain
Crosstalk at 1 kHz: -90 dB <=-80 dB set for 0 dB gain, no limiting, terminate the
Crosstalk at 10 kHz: -70 dB <=-60 dB
Frequency response: 20 to 15 kHz +0/-1.0 dB reference 1 kHz, measured at 0 dB gain and with
400Ω
+17 dBV
1% impedance at 1 kHz
+
>=+17 dBV
1 kHz, THD less than 0.1%, load 10 kΩ,
differential
unused input with a 50 Ω resistor
0 dB output
8
SPECIFICATIONS
Power Amplifier
Nominal Limits Conditions
Power bandwidth:
Frequency response:
THD+N@ 70.7 Vrms
200W:
THD+N@ 70.7 Vrms
400W:
THD+N@ 100 Vrms
200W:
THD+N@ 100 Vrms
400W:
Sensitivity@ 70V:
Sensitivity@ 100V:
Gain:
Output noise:
Crosstalk at 1 kHz:
Crosstalk at 10 kHz:
Turn on/off pop:
30 Hz to 20
kHz
30 Hz to 20
kHz
.05%
.5%
.05%
.5%
11 dBV +
14 dBV +
26 dB +
-70 dBV -65 dBV A weighted with a 20 kHz filter
-90 dB <=-80 dB set for 0 dB gain, no limiting, terminate the
-70 dB <=-60 dB
10 mV peak <=+
1% THD
+ 3 dB output voltage of 10 Vrms over a load impedance
.1%
1%
.1%
1%
1 dBV
1 dBV
0.5 dB
50 mV
peak
loaded at 25Ω
of 12.5Ω to 1000Ω
30 Hz to 20 kHz, 25Ω load, A weighted
7 kHz, 12.5Ω load, A weighted
30 Hz to 20 kHz, 25Ω load, A weighted
7 kHz, 12.5Ω load, A weighted
unused input with a 50 Ω resistor
as monitored by a listener, must be inaudible at
full gain with an 802
listener.
loudspeaker 3 feet from
9
THEORY OF OPERATION
Power Section Overview
CAUTION: There are dangerous voltages present on most of the power supply and amplifier
circuitry. Under normal conditions, it can take 3 to 5 minutes after power is removed for these
voltages to discharge to a safe level. Please use extreme caution and resist the temptation to
probe during this period.
The FreeSpace® E-4 is a complex system that employs high-voltage direct-coupled Class-D
switching power amplifiers, four separate microcontrollers (uCs), and numerous DSP, interface,
memory, logic, analog and communication devices. The accompanying software includes error
flagging and logging features that will usually help you isolate the cause of any failures.
Included in this manual are block diagrams of the complete E-4 unit and a power amplifier
channel. These provide a simplified view to help you find the related area in the detailed
schematics.
Power Supply
The E-4’s power supply section consists of four sections. First is the main high-voltage DC
supply formed by the toroidal 50/60 Hz transformer, bridge rectifier (BR1) and filter capacitors
(C1-C4). This is a conventional unregulated split supply (the only addition is SW1 to change
transformer secondary taps). The raw DC output is about + 130VDC when SW1 is set for 70
volt output, and + 170VDC when SW1 is set for 100 volt output. At full power output and nominal line voltage, these sag to about + 110V and + 150V respectively. Fuses F1-F4 provide “fire
protection” in the event of a catastrophic power amplifier failure.
The next power supply section, formed around TOPswitch® regulator U2 and transformer TR2,
is referred to as the “Standby Supply” because it is operational whenever power is applied to
the unit and the rear panel power switch is on. Its purpose is to supply approximately 9 volts
(locally regulated to 5 volts) to several microprocessors and other circuitry. These microprocessors respond to turn-on stimuli, i.e. power-up via the E-4’s real-time clock, computer control or
user intervention via standby switch or wall plate. The TOPswitch IC performs all the functions
of a complete 130 kHz SMPS flyback-mode controller and switch, i.e. slow-start, current limit,
overvoltage lockout, fswitch dither, low current skip-cycle, etc.
The other, large TOPswitch section formed around U1 and TR1 response to “wakeup” commands from the E-4’s main host processor, which operates from the standby supply. It provides
+ 22 volts (locally regulated to + 15V) and +10 volts (locally regulated to + 5V and + 3.3V)
which powers multiple analog, DSP, communications and indicator sections throughout the E-4.
The forth output from U1 and TR1 (labeled -160) is more accurately described as “180 volts
above the minus rail”. This voltage is locally regulated to 12 volts, and provides the gate-drive
current for the main output FETs.
Also included on the power supply schematic sheet are two other ancillary circuits. U3A is a
resettable one-shot whose output is normally high with AC power applied. If there is an AC line
dropout exceeding approximately 2 cycles, a logic 0 from U3A is used to immediately shut
down the amplifiers and DSP in time to save all current configuration data and prevent any
spurious thumps etc. from appearing at the speaker outputs.
Q1 and Q2 form a simple buffer that switches the cooling fan from low to high speed if either of
the Fan-U or Fan-L signals are at logic 0. This occurs when the power amplifier thermal sensors report a heatsink temperature of over 160oF.
10
THEORY OF OPERATION
Power Amplifier
The E-4’s power amplifier section employs a number of protective devices and communication
circuits to ensure continued reliable operation, and to enable reporting and logging of any fault
conditions. In addition, there are several measurement circuits, whose primary purpose is to
provide information to Bose® FreeSpace® Installer™ software, enabling it to verify proper
configuration of the E-4 unit itself, and the speakers connected to it. The block diagram provides a simplified view of one of the four channels, however many of the peripheral functions
are shared with one or more other channels. Refer to the detailed schematic for more information on exactly how the circuitry and functions throughout the units various PCB assemblies.
The power amplifier module itself consists of a single heatsink assembly with two circuit boards
mounted to it back-to-back. The upper PCB contains amplifier circuitry for output zones (channels) 1 and 2; the lower PCB contains amplifier circuitry for output zones 3 and 4, plus power
supply components shared by the entire unit. The power amplifier module receives analog
inputs and 2-way serial communications from the E-4’s DSP and host processor sections via a
34-pin ribbon cable. Power is also supplied from the Amp/PS module to the rest of the unit via
this cable.
Component designators in the block diagram (page 72) refer to channel 4, see the detailed
schematic diagram to find appropriate designators for other channels. The core of the power
amplifier section is a pair of high voltage MOSFETs (Q10 and Q11). These are driven by a
“Class T” hybrid control module from modulation pattern to drive Q10 and Q11’s gates. Contained in the hybrid module itself are a proprietary analog/DSP IC operating from a single +5
volt supply, and a pair of high voltage half-bridge gate drive chips including charge pumps for
high-side drive. There are also other discrete components to perform level translation, gain
scaling, buffering, etc.
The Tripath’s modulation pattern has a no-signal center frequency of about 700 kHz. The
switching frequency varies downward as the signal level increases, reaching about 100 kHz
just before clipping. Near clipping, the switching pattern is further adjusted to provide soft
clipping behavior. This appears to be oscillation when viewed on a scope, but all of the artifacts
are well above the audio band, and the “fuzz” actually helps reduce the audibility of clipping.
Choke L4 and capacitor C41 form a 2-pole low-pass filter at approximately 70 kHz to remove
the switching frequency from the audio output. C42, R84 and R85 are a Zobel network whose
main function is to damp the resonance of the L4/C41 filter with very high impedance or nonexistent speaker loads. This network also does double duty: the voltage across R84 and R85 is
rectified to determine if the amplifier is being fed a signal with too much high frequency content. You’ll notice that there is no analog feedback from the audio output. All of the feedback in
the amplifier is derived by comparing the actual FET switching transitions with the predicted
transitions, thus avoiding the inherent delay of the output LC filter. “Servo Amp” A1 provides DC
feedback to insure that the entire amplifier’s output DC offset remains very low. This is especially important in distributed sound applications, where the speakers are connected through
matching transformers that have very low impedance at DC.
The voltages across R87 and R86 are sensed differentially and level-shifted within the Tripath
module (this is how excessive current i.e. a shorted load is determined). This over-current, or
main rail voltages that are too high or too low will cause the module to shut down very quickly
and output a logic 1 on the module’s “Fault” pin.
11
THEORY OF OPERATION
Protection
PIC microcontroller, U14, monitors amplifier functions including the Tripath’s “Fault” pin (and
numerous other inputs) and responds by turning the amplifier on and off by means of the
Tripath’s “Mute” pin. The speakers are also disconnected under U14s control via relay K1. In
order for the amplifier to become fully functional at start-up, the following conditions must be
true:
1. The AC power must be OK.
2. The heatsink temperature must be below 160
3. The “Wakeup” line from the host processor must be high.
4. The “Amplifier Off” command (I2C) from the host processor must be absent, i.e. set to
“On”.
5. The main rail voltages must be within prescribed limits (
6. There must not be DC at the output (after a 1 second “servo setting time”).
7. There must not be excessive high frequency content at the output.
In addition to this series of tests at start-up, the determination is made whether the unit is set
for 70V or 100V output by measuring the + rail voltage <140V = 70V mode, >150V = 100V
mode. 70V mode causes a 1 (+5V) output on U14s “Vshift” pin. This 1 causes a small amount
of current to be sourced/sunk into Tripath pins 37 and 38. These currents cause the Tripaths
internal Overvoltage/Undervoltage limits to shift downward corresponding to the
vs. + 170V.
o
F.
+100-190V).
+ 130V rails
Once the amplifier is up and running, all of these parameters are monitored continuously, with
a few minor adaptations. If the heatsink temperature exceeds 160oF, the fan is switched from
low to high speed operation. If the power dissipation is still excessive, and the heatsink ex-
o
ceeds 210
F, the amplifier will be shut down until the temperature is under 160oF. Once the
initial voltage measurements are made, the Tripaths internal overvoltage/undervoltage sensing
is relied upon.
If anything other than a shutdown command causes the amplifier to go into protect mode (i.e.
AC dropout, overvoltage/undervoltage, short circuit, DC or high frequency), the speakers are
immediately disconnected, and the amplifier is shut down for approximately 2.5 seconds. It is
then restarted and checked again after a 600 mSec. stabilization period. If everything is not
OK, 6 more off-wait-stabilize-reset cycles are attempted, normal operation can resume after
any of these. If after 6 retries, 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.
Measurement
Measurement of the rail voltages and numerous other parameters are accomplished via an
internal 10-bit A/D converter section in PIC uC U14. Most inputs to the A/D are multiplexed
(under the PIC’s control) via 8-channel analog switch U15. The A/D’s output is truncated to 8
bits and incorporated into the I2C datasteam going to the host processor on the DSP PCB.
Heatsink temperature is monitored via U12, which provides a calibrated output of 10mV/oF.
Several gain, precision rectifier, average circuits are provided to condition the following signals
for measurement via the MPX - A/D section (via voltage across R91):
1. Amplifier input voltage, 2. Amplifier output voltage, 3. Amplifier output current.
To provide repeatable, reliable measurements, the time constant of all these averages is
approximately 100 mSec.
12
THEORY OF OPERATION
Measurement (continued)
®
Bose
FreeSpace® Installer™ software uses these measurements to calculate answers to
questions , such as; “Is the amplifier set up and running properly, and providing adequate
output voltage?” “Is the speaker line tapped for the proper output power on this Zone?”
Fault Logging
The amplifier PIC processors are in continuous communication with the E-4’s host processor
via the I2C serial link. Pin 26 of the PIC is connected high or low on the two amplifier PCBs so
the host can distinguish between the upper or lower amplifier PCB. If any of the events mentioned in the protection section cause the amplifier to shut down, an “Amplifier Status Record”:
plus a set of amplifier measurements (V
out, Iout, TEMP, Vrail, etc.) is saved into flash memory.
Some of the more common fault conditions can be identified by careful dissection of these
status records. FreeSpace Installer software will automatically identify these, but if you are
using the E-4 Term unity, you can observe the input status and output status boxes for each
amplifier PCB. These status codes are in hex format; converting them to binary allows observation of the individual status bits.
Input Status Bits:
X = Normal Operation Output Status Bits: X = Normal Operation
0 (MSB) = Normal 1=Retry fault (6x) 0 (MSB) = Amp On 1 = Tripath mute (Off)
0 = Hi Freq. fault 1 = Hi Freq. OK 0 = Speaker relay Off 1 = Speaker relay On
0 = Wakeup Off 1 = Wakeup On 0 = Fan @ low speed 1 = Fan @ high speed
0 = Power not OK 1 = AC power OK 0 (LSB) =100V speed 1 = 70V mode
0 = Tripath module OK 1 = Tripath fault
0 (LSB) = DC fault 1 = DC sense OK
Amplifier Operating States
Pins 4, 5 and 6 on the PIC programming headers (JP1 lower) or (JP2 upper) provide a binary
indication of which one of 6 states of operation the amplifier is in. If you monitor these pins, you
can observe the states being walked though, and determine where operation is getting interrupted. The order is pin 4 = MSB, pin 6 = LSB. For example, if pins 4, 5 and 6 measured high
(+5V), high (+5V), low (0V), you would be in state 6. Some of the states are transitioned
through so quickly that you would need a storage scope to verify operation in that state (ex.:
state 4). Below is a brief description of the states:
State 0 Amps and speaker relay OFF-waiting for Wakeup and/or Amp On command.
State 1 Delay- Wakeup received, wait 1 second for rail voltages to stabilize.
State 2 Test supply rails - return to state 0 if out of range. If OK, set to 70V or 100V mode
according to rail voltages.
State 3 Un-Mute (turn-on) amplifier (speakers off). Return to state 0 if Off command
received. Wait 1 second, but go to state 6 immediately if high frequency input
detected.
State 4 Test for power OK, DC, high frequency, overheat, etc. + Tripath faults. Go to state 5
if OK. State 6 if not OK.
State 5 Normal operation - Set speaker relay On (amp still running). Reset retry count to 0.
Watch continuously for Off commands or any faults.
State 6 Retry state. If retry count = 6, go to state 0. Mute amp, set relay Off. Add 1 to retry
count. Wait 2.5 seconds, then go to state 3.
13
THEORY OF OPERATION
A
E4 DSP Theory of Operation
1. Overview
The E-4 DSP section consists of five boards manufactured as a single panel. Unregulated power
is distributed to the boards and each, except the flash card, contains its own regulators. The DSP
board contains the 56K DSP and the 80C251 host processor along with its subordinate PIC
processor for peripheral control. This board also carries the audio codecs and their associated
analog circuitry. Two audio inputs are line level and two may be configured for 0 to 60 dB of gain.
The direct input bypasses the DSP and codecs and allows a signal to directly drive the amplifier
system. A ribbon cable transports the audio output signals, various control and monitoring signals,
and raw power between the amplifiers/power supply and the DSP system.
flash memory chip that holds the host operating program and system configuration information is
mounted on a small card that plugs into the processor board. The front panel board holds the front
panel indicator LEDs, standby button, and the USB interface connector. The wall plate connectors,
contact closure input, direct audio output, and music on hold output are on the mezzanine board at
the back of the unit. The auto-volume sense microphone input board is mounted above the
mezzanine board and also contains the RS-232 connector.
When the system is on, it can be in one of two states: standby or operating. When the system is in
standby, the host and peripheral processors are powered up and functioning as are the front panel
and wall plate sense boards. The power to the amplifiers, the auto-volume microphone sense
board, the DSP section and the analog I/O circuitry and codecs is shut down. When you bring the
unit out of standby all sub-systems are powered.
2. DSP Board
Digital power on the DSP board is regulated by a 5 volt (U547) and a 3.3 volt (U550) voltage
regulator. The analog section of the board, running from plus and minus 15 volts (U548) (U549),
and 5 volts (U551), is powered only when the system is not in standby. Power on system reset is
managed by (U552).
The DSP is a Motorola 56362 (U517) running at 112.896 MHz. An internal PLL multiples the
22.579 MHz crystal oscillator (U527) frequency by five. The oscillator runs from the 3.3V supply
and also drives a D flip-flop divide by 2 and level shifter that is made from ½ of (U525). The
112.896 output drives the MCLK inputs of the audio codecs and (U526) synchronous counter that
serves as the clock divider chain to provide the 2.822 MHz SCLK and the 44.1 kHz LRCK.
The DSP sub-system also has flash memory (U516) and three 128K by 8 static RAMs (U513,
U514, U515) running from the 3.3 volt power supply. The host processor holds the DSP subsystem in reset with power off when the E-4 is in standby.
The host processor sub-system is always running when the E-4 is powered up. The host
processor sub-system consists of (U520), an octal D flip-flop (U519) to latch the low order address
lines, (U521) used as a memory block decoder, (U518) a 32K by 8 static RAM and (U701) the
flash memory on the daughter card. It communicates with the outside world through its RS-232
port buffered by a MAX202E (U524) or through the USB interface on the front panel board.
The microprocessor (U544) serves as a peripheral controller to extend the I/O capacity of the
(U520). The host communicates with it over the I
the USB bus interface (U106) that is mounted on the front panel board. Pressing the standby
button on the front panel sends a signal to the PIC that is relayed to the host over the I
The host then sends a wakeup signal to the power supply by lowering a port line that is buffered
by one section of (U522) that in turn drives PNP inverting transistor Q501.
2
C bus along with the real time clock (U523) and
2
C interface.
14
THEORY OF OPERATION
2. DSP Board (continued)
Strobe signals from the PIC drive three gates on (U522) to gate serial clock signals from the host
that drive the three audio attenuators (U531, U203, U211) in the system, one on the DSP board and
two on the mic sense board. These gated clocks along with the serial data line and the I/O clock for
the wall plate board then are buffered through (U553) so that drive is disabled when the unit is in
standby and power is removed from the DSP analog section and the two rear auxiliary boards.
Two serial in, parallel out shift registers (U545, U546) are driven by the PIC to provide control bits to
the gain controls on the two mic inputs. The final output bit from the second shift register, controls
NPN transistor Q503 to output a control signal.
The PIC also contains an eight input 10 bit A/D converter. The four sense lines from the auto
volume mic sense circuits drive the first four inputs and the four sense lines for the amplifier sense
circuits drive the second four inputs. Each input has a .01 uF capacitor to minimize high frequency
noise and a dual protection diode connected to ground and the 5V power rail. Header JP501 is
present to allow the PIC to be programmed on the circuit board.
The analog section of the DSP board contains the two stereo codecs (U503, U507) and their
associated analog input and output circuitry. Line 1 and 2 each have two inputs that are resistively
mixed and buffered through difference amplifiers (U529, U532). Each of the difference amplifiers
feed a channel of the volume control (U531) that in turn drives the two dual op-amps (U501, U504)
that convert the single ended signals to differential drive for the codec.
Mic in and Page in are balanced inputs, each driving an instrumentation amplifier (U537, U540).
These two channels each have a voltage regulator (U536, U539) that can be enabled by the host to
provide phantom power to external mics. The gain of the voltage regulator is controlled by the host
switching on analog switch sections (U541, U542, U543) that connect gain control resistors. The
range of gain is 0 to 60 dB in 10 dB increments.
The outputs of the instrumentation amplifiers are each served by ½ of an op amp (U538) to a fixed
DC offset of 2.5V to provide one half of the differential drive to the second codec. Each channel is
inverted by half of a dual op-amp (U505) to provide the second phase of differential drive to the
codec. Each of the four input channels is fed to a multiplexer (U535) that selects one channel under
host control for output as music on hold.
The four differential outputs of the codecs drive four identical circuits built around switchable
amplifiers (U509, U510, U511, U512). One differential input of each is configured as a low-pass filter
and differential to single ended converter and is fed from a codec output. The second input of is
connected to a common input signal, the direct input. A PNP transistor circuit (Q502) detects ground
on the PTT input and switches the switchable amplifiers to the direct input while also signaling the
PIC to inform the host that an override is happening. The four switchable amplifiers drive the power
amplifier inputs from the selected input signal path.
The outputs from the switchable amplifiers also drive four channels of amplitude sense circuitry.
Each sense path consists of an op-amp gain stage followed by a low pass filter, a high pass filter
and a precision rectifier/average circuit. The op-amps are contained in dual op amps (U700, U706)
and quad op-amps(U702, U703, U704, U705).
15
THEORY OF OPERATION
3. Front Panel Board
The front panel board contains the front panel indicator LEDs, the standby switch and the USB
connector and interface circuitry. Power is applied to this board even when the E-4 is in standby
and is regulated to 5V by U105 voltage regulator and to 3.3V by U107 voltage regulator. Serial
input from the host on the DSP board drives a sequence of three serial in, parallel out shift
registers (U102, U103, U104) to drive the LEDs. To reduce power consumption three inverters
from U101 are configured as an oscillator to multiplex the LED drive. Two more of the inverters are
used to buffer and debounce the standby switch. When the standby button is pushed the signal is
detected by the PIC processor on the DSP board, which then communicates over the I
the host processor. The I
2
C lines also come onto the front panel board to allow the host processor
to communicate with an external PC through the USB interface IC (U106).
4. Auto-volume Microphone Sense Board
The auto-volume microphone sense board contains the input and level control circuitry for four
sense mics and an RS-232 connector to allow the E-4 system to communicate with an external
PC. Power is not applied to this board when the E-4 is in standby. The board regulates analog
power supply voltages with a positive 15V regulator (U216) and a negative 15V regulator (U215).
There is also a positive 8V regulator (U204) to provide power to the external sense mics.
Each mic sense path consists of input protection circuitry and a resistor to the 8V supply followed
by a 330uF DC blocking capacitor, input protection diodes to the plus and minus 15V rails and an
op-amp serving as an input gain stage of 37dB. The output of the op-amp passes through another
DC blocking cap to ½ of a volume control IC. This output passes through another capacitor into an
op-amp gain stage followed by a low-pass filter, a high pass filter and finally a precision
rectifier/average circuit and off the board to one of the PIC A/D inputs. There are two attenuators
(U203, U211), two dual op amps (U206, U213) and four quad op amps (U207, U208, U214, U215)
on the board.
5. Wall Plate Sense Board
The wall plate sense board contains the circuitry to scan up to four wall plates that are connected
through four RJ-45 jacks and to drive the LEDs on the wall plates. In addition there are connectors
and passive protection components for the music on hold output, the line 4 expansion output and
its associated control line, and the control input to allow an external device to wake up the system.
Power is applied to the board even when the E-4 is in standby and is regulated for the board and
the external wall plates by a voltage regulator (U401). The wall plate input lines are scanned by
three parallel in, serial out shift registers (U404, U405, U406) Resistors on the wall plate sense
board pull the input lines up, switch closures on the wall plates pull the inputs down. Two serial in,
parallel out shift registers (U402, U403) apply multiplexed drive to the LEDs on the wall plates in
the interim when the switches are not being scanned.
6. Flash Memory Board
The flash memory card is powered from the main DSP board. The board contains a 2 Mb 5V flash
ROM (U701) and power supply bypass capacitor. This memory stores the system configuration
data as well as the host microprocessor operating program.
2
C bus with
16
DISASSEMBLY/ASSEMBLY PROCEDURES
Note: Refer to figure (2) for the following
procedures.
1. Top Cover Removal
1.1 Remove the eighteen screws (1) that
secure the top cover to the chassis.
1.2 Lift the rear of the top cover (2) up and
remove it from the chassis.
2. Top Cover Replacement
2.1 Place the top cover (2) onto the chassis
and secure it using the eighteen screws (1)
removed in procedure 1.1.
3. LED Display PCB Removal
3.1 Perform procedure 1.
3.2 Remove the four screws (18) that
secure the LED PCB (19D) to the front
panel and remove the PCB.
3.3 Disconnect the wire harness (23) from
the LED display PCB (19D).
4. LED Display PCB Replacement
4.1 Connect the wire harness (23) to the
LED PCB.
4.2 Secure the LED PCB (19D) to the front
panel using the four screws (18).
6. Fan Replacement
6.1 Secure the fan (3) to the chassis using
four nuts (4) removed in step 5.3.
6.2 Connect the fan harness to the power
amp/power supply PCB (27A).
6.3 Perform procedure 2.
7. Audio Source/DSP PCB Removal
Note: This is a PCB assembly. There are
three PCBs being removed in the following
procedure. The two smaller PCBs can be
removed once this procedure is performed.
7.1 Disconnect the LED harness (23) and
the power/output harness (24) from the
DSP/audio source PCB (19A).
7.2 Remove the six screws (16) that secure
the DSP/audio source PCB (19A), wall
plate PCB (19C) and the sense
microphone PCB (19B) to the rear panel.
7.3 Remove the two nuts (17) that secure
the RS232 connector to the rear panel.
7.4 Remove the two screws (18) that
secure the DSP/audio source PCB (19A)
to the bottom of the chassis and lift the
PCB out of the unit.
8. DSP/Audio Source PCB Replacement
4.3 Perform procedure 2.
5. Fan Removal
5.1 Perform procedure 1.
5.2 Disconnect the fan harness from the
power amp/power supply PCB assembly
(27A).
5.3 Using a 5/16" nut driver remove the four
nuts (4) that secure the fan (3) to the
chassis.
8.1 Place the DSP/audio source PCB
assembly (19A-C) into the chassis (This
will include the other two PCBs connected
to the audio PCB).
8.2 Secure the DSP/audio source PCB to
the chassis using the two screws (18)
removed in step 7.4.
8.3 Secure the DSP/audio source PCB
assembly to the rear of the chassis using
the six screws (16) removed in step 7.2.
8.4 Replace the two nuts (17) removed in
step 7.3.
17
DISASSEMBLY/ASSEMBLY PROCEDURES
8.5 Connect the LED harness (23) and the
power/output harness (24) to the DSP/
audio source PCB.
8.6 Perform procedure 2.
9. Power Supply/Power Amp PCB Removal
9.1 Perform procedure 1.
9.2 Disconnect the large gray wire harness
(24) from the DSP PCB.
9.3 Remove the three screws (18) that
secure the PCB to the chassis.
9.4 Remove the three 11/32" nuts (26) that
secure the heatsink assembly (25) to the
chassis.
9.5 Remove the four screws (16) that
secure the PCB (27A&B) to the rear panel.
10.6 Connect the large gray wire harness
(24) to the two power amp PCBs.
10.7 Perform procedure 2.
11. Power Amp PCB Removal from the
Heatsink (smaller PCB)
Note: Refer to figure 1 for the following
procedure.
11.1 Perform procedure 9.
11.2 Disconnect the harness going to the
smaller PCB (4B) (outputs 1 and 2).
11.3 Using a flat blade screwdriver, lift the
top of the transistor clip (3) out of the
groove on the heatsink assembly.
11.4 Remove the two screws (1) that
secure the PCB (4B)to the heatsink (2).
9.6 Slide the heatsink/PCB assembly
forward while lifting the front of the PCB up
slightly.
9.7 Disconnect the fan harness from the
bottom PCB assembly and lift the heatsink
assembly out of the chassis.
10. Power Supply/Power Amp PCB
Replacement
10.1 Place the heatsink/PCB assembly into
the chassis.
10.2 Connect the fan wire harness and
slide the assembly towards the rear panel.
10.3 Secure the rear of the PCB assembly
using the four screws (16) removed in step
9.5.
10.4 Secure the heatsink to the chassis
using the three 11/32" nuts (26) removed in
step 9.4.
11.5 Gently lift the PCB off of the two
standoffs (5). You might have to squeeze
the standoff with pliers in order to lift the
PCB off easily.
12. Power Amp PCB Replacement to the
Heatsink (smaller PCB)
12.1 Place the PCB (4B) into the slot on
the heatsink and snap it onto the standoffs
(5).
12.2 Secure the back of the PCB to the
heatsink using the two screws (1) removed
in step 11.4.
12.3 Place the transistor clips (3) onto the
transistors and push them into the groove
on the heatsink.
13. Power Amp/Power Supply PCB
Removal from the Heatsink (larger PCB)
13.1 Perform procedure 9.
10.5 Secure the PCB assembly to the
chassis using the three screws (18) removed in step 9.3.
13.2 Disconnect the harness going to the
larger PCB (4A) (outputs 3 and 4).
18
DISASSEMBLY/ASSEMBLY PROCEDURES
13.3 Using a flat blade screwdriver, lift the
top of the transistor clip (3) out of the
groove of the heatsink assembly.
13.4 Remove the two screws (1) that
secure the PCB (4A) to the heatsink (2).
13.5 Gently lift the PCB off the two standoffs (5). You might have to squeeze the
standoff with pliers in order to lift the PCB
off easily.
14. Power Amp/Power Supply PCB
Replacement to the Heatsink (larger PCB)
14.1 Place the PCB (4A) into the slot on the
heatsink and snap it onto the standoffs (5).
14.2 Secure the back of the PCB to the
heatsink using the two screws (1) removed
in step 13.4.
Note: Refer to figure 2 for the following
procedures.
15. Power Transformer Removal
15.1 Perform procedure 1.
15.2 Disconnect the power transformer
harness from the power supply/power amp.
15.3 Remove the 9/6" bolt (5) that secures
the power transformer (8) to the chassis.
16. Power Transformer Replacement
16.1 Secure the power transformer (8) to
the chassis using the 9/16" bolt (5) removed in step 15.3.
16.2 Connect the power transformer harness to the Power supply/power amp PCB.
14.3 Place the transistor clips (3) onto the
transistors and push them into the groove
on the heatsink.
2
x4
1
3
x8
4A
x2
5
4B
Figure 1. Amp PCB and Heat Sink Assembly
19
TEST PROCEDURE SETUP
Equipment Requirements
A 400 MHz, Pentium
®
- based PC.
256 MB RAM.
50 MB of available hard drive space.
800 x 600 display.
4x CD-ROM drive.
One of the following operating systems: Microsoft® Windows® 98, Windows® 98 SE, Windows
NT, Windows® 2000, or Windows® ME.
An oscilloscope.
A signal generator similar to an Audio Precision ATS-1.
A multimeter.
An RS-232 serial cable.
Four 100 Ohm, 50 Watts or greater loads, one for each output zone.
®
®
The Bose
FreeSpace® Installer™ software version 1.0 or higher.
System Setup
To connect to an E-4 system you must first have the FreeSpace® Installer™ software installed
on your PC.
1. Connect the RS-232 serial data com port of your PC to the RS-232 serial port on the rear
panel of the E-4 using an RS-232 DP9 connector serial cable.
2. Set the E-4 rear panel power switch to the on position. When the E-4 unit is powered up and
ready, the system status indicator is green and the standby indicator is amber.
3. With the unit in standby or on status, launch the Installer software.
4. If for any reason the E-4 unit will not power up, or turns on then shuts itself off, you will need
to repair the unit before proceeding. If the unit connects to the software, continue to the system
setup procedure.
20
TEST PROCEDURE
Launch the FreeSpace® Installer™ Program
Once the unit is connected and the software has been launched, the following window will
appear.
If the window below is displayed check the connections to the computer as well as the power
connection and power switch. Be sure the amber system status indicator on the front panel is
on.
Finally, once the system is connected correctly and power is restored the following window will
appear, click OK.
21
TEST PROCEDURES
System Status Conformation
Once connected to the computer you should see a window like the one below. If you do the
system is operating normally.
Service Status Conformation
Click on the service hardware box to display the screen below and scroll through the text
window for system status information.
22
TEST PROCEDURES
Line 1 Into Zone 1 Output
1. Assuming you have connected the E-4 unit to the PC using the instructions on the previous
pages, select the output gain box for zones 2 through 4 and check the mute box for each of
the zones.
2. Select the input box for Line 1 and set the gain control to 20 dB. Select the output gain box
and set the gain control to -60 dB.
3. Select the Source Assign, Auto Volume, Dynamic EQ, and EQ boxes and set them as
shown below.
4. In the source assign box, the yellow speaker indicates where the input signal is set to. For
this test we want it to come from Line 1 as shown above.
5. Apply a 630 mVrms, 1 kHz signal to the Line 1 input on the E-4. The output of all 4 zones
should be loaded with 100 Ohm, 50 Watts or greater.
6. Check the input indicator for a green, yellow and red display. Also check the small LED in
front of the input gain box. It should be green.
7. Reference a dB meter to the input. Measure the output of Zone 1. The reading should be
8.5 dB
8. Adjust the input voltage until the LED in front of the input gain box changes to red. The input
level should be < 645 mVrms.
9. Repeat steps 1 through 8 for zones 2, 3 and 4. Mute all zones that are not being tested.
10. With the applied signal set to 630 mVrms, 1 kHz select the Source Assign box for zone
2, 3 and 4. Select the Line 1 signal source.
11. Select the output gain box and unmute the output on all zones. The LED for all four zones
should be green.
12. The output reading for all 4 Zones should be 41.5 dB + 3 dB.
+ 3.0 dB.
23
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