Bose ACM-1 User manual

©1999 Bose Corporation Service Manual
®
®
Part Number 199746 Rev. 00
ACM-1 Amplifier Control Module

2
CONTENTS
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.
CAUTION: The ACM-1 Amplifier Control Module contains
no user serviceable parts. To prevent warranty infractions,
refer servicing to warranty service centers or factory service.
Safety Information............................................................................................................................ 3
Electrostatic Discharge Sensitive (ESDS) Device Handling ........................................................ 4
Warranty Information ....................................................................................................................... 4
Figure 1. ACM-1 Audio Section Block Diagram................................................................................ 5
Figure 2. ACM-1 Monitoring Section Block Diagram........................................................................ 6
Theory of Operation.................................................................................................................... 7-10
Disassembly/Assembly Procedures ....................................................................................... 11-12
Figure 3. Input Module Screw Removal..........................................................................................11
Figure 4. ACM-1 Default Switch Settings ....................................................................................... 11
Figure 5. 1800VI Ribbon Cable Connector Location (ACM-1 J8 to 1800VI J2) ............................ 11
Figure 6. ACM-1 J1 Ribbon Cable Connection .............................................................................. 12
Test Procedures ........................................................................................................................ 13-19
Table 1. ACM-1 Input, Output, and Power Connections................................................................. 13
Table 2. PS71 Power Supply List ................................................................................................... 13
Figure 7. ACM-1 Switch Settings ................................................................................................... 14
Figure 8. 1800VI Rear Panel Switch Settings................................................................................ 14
Figure 9. ACM-1 Graphical User Interface Control Panel .............................................................. 15
Table 3. Amplifier Output Performance Tests ................................................................................. 16
Test Cable Construction ............................................................................................................... 19
Part List Notes................................................................................................................................ 19
Main and Packaging Part list, ACM-1 Amplifier Control Module (see Figure 10)..................... 20
Figure 10. ACM-1 Amplifier Control Module Exploded View .......................................................... 20
Electrical part list ...................................................................................................................... 21-25
Figure 11. Daughterboard Topside Etch Layout Diagram .............................................................. 26
Figure 12. Daughterboard Internal Etch Layout Diagram .............................................................. 26
Figure 13. Daughterboard Bottom Etch Layout Diagram ............................................................... 26
Integrated Circuit Pinout Diagrams.........................................................................................27-29

3
SAFETY INFORMATION
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
(1) 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) 1492 (71).
(2) With the unit AC switch first in the ON position and then in the 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.
(3) Any current measured must not exceed 0.5 milliamp.
(4) 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 the exposed
metallic part has a return path to the chassis, the reading should be
between 1 and 5.2 Megohms. When there is no return path to the chassis,
the reading must be "infinite". 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.

4
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.
WARRANTY INFORMATION
•The ACM-1 Amplifier Control Module is covered by a 5-year transferable limited warranty.

5
Clock Logic
U21
8VCLK
3 13 14 22
DATA I08
ENABLE I07
Buffer Driver
U8
Buffer Driver
U7
Buffer Driver
U7
Buffer Driver
U8
Protection
Circuitry
Protection
Circuitry
Protection
Circuitry
Protection
Circuitry
Digital
Attenuator
0 -100 dB
U14
Switchable
Inverter
U11
Selector
U13
Selector
U12
Selector
U10
Eq Card 2
Eq Card 1
HF Switch
SW2
Protection
Circuitry
Protection
Circuitry
Balanced
Unbalanced
Balanced
Unbalanced
Mode Switch
U16
U15
A
IN1+ IN1- GND
A
IN2+ IN2- GND
3
2
SW1B
SW2B
SW2A
SW1A
HF1
HF2
3
2
6
2
7
5
0
1
1
2
1
5
7
2
1
5
21
4
3
3
5
5
7
2
5
1
6
1
0
1
1
A A
P2
CH. 2 EQ OUTPUT
AMP IN 2
J1-20
AMP IN 1
J1-16
CH. 1 EQ OUTPUT
P3
7
7
SW1B
SW2B
SW1A SW1B MODE
0
0
1
1 1
0
don't care
don't care normal
normal
dual mono
bridged
Truth Table
J6-5
J6-4
12
Figure 1. ACM-1 Audio Section Block Diagram

6
Rectification
Rectification
Mean
Peak
Mean
Peak
Current
Sense Rectification Mean
Divider
Current
Sense Rectification Mean
Divider
Rectifier
Regulator
Wired 'OR'
A
D
Gnd.
+5Vdc
Standby
Network Power (dc / dc)
Adapter Power (ac / dc)
Amplifier Power (dc)
Jumper
I Out +1
I Out +2
V2_Peak
V2_Mean
V1_Peak
V1_Mean
I1_Mean
I2_Mean
I Out 1+
I Out 1-
I Out 2+
I Out 2-
Thermal
Sensor
Neuron
Micro-
processor
Level Shifting
Multiplexer
Analog to Digital
Converter
10-bit Serial
Therm 1
Therm 2
106 dc
Standby
Protect 1
Protect 2
Aux 1
Aux 2
V1_Mean
V1_Peak
V2_Mean
V2_Peak
I1_Mean
I2_Mean
Amplifier
Data
Activity
LED
Service Pin
Service LED
Gnd.
Network Power
Power-up
Network (LonWorks ® )
Signals to Amplifier
Amp In 1
Amp In 2
Power-up
LED
Data Bus
Signals from Amplifier
Therm 1
Therm 2
Rail Voltage
+I Out 1
-I Out 1
+I Out 2
-I Out 2
Protect 1
Protect 2
Figure 2. ACM-1 Monitoring Section Block Diagram

7
THEORY OF OPERATION
G
eneral Description:
The Bose
®
ACM-1 Amplifier Control Module is an optional replacement for the standard
Input Module that is delivered with the Bose 1600 and 1800 Series VI Power Amplifiers.
This module, which installs into the back of the amplifier in place of the standard input
module, adds a network interface to the power amplifier; allowing the user to control and
monitor the amplifier(s) remotely and simultaneously. This can be done only when the
amplifier is in standby or 'sequence' mode, which is set on the front of the amplifier. The
network topology used by the ACM-1 Amplifier Control Module is the LonWorks
®
network
standard which is a registered trademark of Echelon
®
Corporation. The device controlling
the amplifier(s) may be a personal computer or any other 'smart' device that incorporates
a LonWorks
Neuron
®
module.
The Bose ACM-1 uses a LonWorks Neuron module to translate network polls into
addressing, reading and writing commands used to control the amplifier. This device
contains a network transceiver and a micro-controller interacting with on-board flash-
memory. On the main PCB of the ACM-1, an Analog to Digital Converter (ADC)
translates amplifier operating conditions such as output level, temperature and clipping
level inside the amplifier to digital information to be passed to and from the Neuron module
and ultimately, the network. This information can be monitored with a computer either
locally, tied directly to the control network of the installation, or remotely, provided that the
remote computer has a network connection such as a modem (Internet), Ethernet, or LAN,
and the required software. The amplifier itself is controlled by setting a digital/analog signal
attenuator to manipulate volume level, as well as to switch the amplifier from stand-by
mode to operate mode and vice versa.
The ACM-1 is normally fed stand-by power by an external 12 Vrms AC power adapter
when the amplifier is off or in stand-by (sequence) mode. This allows the amplifier to be
turned on remotely by providing a constant power source to the Neuron module and the
Analog to Digital Converter. The amplifier cannot supply power to the Neuron module
when the amplifier is switched off, which is why the AC adapter is required. Without this
keep-alive voltage, the amplifier would not be able to be powered up remotely. Once the
amplifier is operating, the keep-alive voltage could fail and still have the amplifier operate.
Once the amplifier is shut off again, however, the keep-alive voltage must again be
present to allow remote turn-on of the amplifier. The recommended AC power adapter is
the Bose PS71. See Table 2 on page 12 for part numbers for the various models.
The keep-alive voltage input circuitry of the ACM-1 is designed to also allow the use of a
DC external stand-by power source. The nominal power requirements for a DC source
are +12 Vdc at 100 mA. Furthermore, it is also possible to power the ACM-1 via the
network cable. This must be a DC source. Although this mode of powering has its
limitations due to wire length and thickness, this option might be very useful in smaller or
highly segmented applications. To use network power, jumpers at JB1 on the daughter-
board must be set. Place jumpers across pins 1 & 2 and across pins 5 & 6 at JB1. Refer
to sheet 2 of the schematic diagram at coordinates [D5]. The daughterboard is the small
board mounted to the faceplate with the RJ45 connectors on it. Refer to the daughterboard
layout diagrams on page 23. The ACM-1 is shipped with the jumpers uninstalled in order
to avoid RFI noise coupling onto the network wire, which may degrade amplifier
performance when this mode is not used.
Refer to the ACM-1 Schematic Diagram, Sheet 2 of 2, for the following information.
Note: The designators inside the brackets "[ ]" are the schematic grid coordinates which
are provided in order to make it easier to locate components on the schematic sheet
indicated in the description.

8
THEORY OF OPERATION
Power
S
upply
S
ection:
The required keep-alive voltage for the ACM-1 enters the unit at J11 [C7] as V_IN. This
input voltage is rectified, if necessary, by D32 and C44 [C7]. The DC voltage is regulated
by the +5V regulator U18 [C7]. This keep-alive power is required by the components that
allow the amplifier to be powered up remotely, the Neuron
®
module [not shown on
schematic], and the Analog to Digital Converter U9 [Sheet 1, B3]. D31 and D30 [C7]
together form a wired 'OR' gate. This means that if the amplifier is powered-up, the ACM-
1 receives power from it, which is +15 Vdc regulated down to +5 Vdc by U18. If not, the
ACM-1 is powered from the standby power source, which could be an AC adapter, a DC
adapter, or a DC voltage supplied through the network cable. STANDBY [B4] is the
network power source which is passed through R97 [B4] to make STBYOK, which is
passed on to the ADC Multiplexer U17 [Sheet 1, C1/2], and is used to detect if there is
adapter power available, even when the amplifier is turned on. Note that digital ground is
used for the power supply reference in order to keep the analog ground after the +5V
regulator as clean as possible.
The ACM-1 consists of a power supply section, an analog section, which is the audio
signal path to the power amplifier, and a digital section which controls and monitors the
amplifier.
Note: The schematics and theory of operation of the neuron module will not be covered in
detail in this section.
Refer to the ACM-1 Schematic Diagram, Sheet 1 of 2, for the following information.
Audio signal path:
The input stage is a balanced input receiver composed of U15 and U16 [C/D7]. The input
is taken from either the combi input connectors [D2/3] or the euro screw terminal inputs at
J4 and 5 [Sheet 2, B7]. The shield ground is decoupled from the analog ground by
capacitors C14 and C15. All inputs have spark gaps to avoid possible damage due to
static electricity. All input legs have RFI low-pass filters [C/D 7/8] and diode clamps to
protect the op-amps against overload. The input impedance in each leg is approximately
25k Ohms and is laser trimmed for good common-mode rejection.
After the input signal is converted from balanced to unbalanced, the signal enters
switchable op-amps U10 and U12 [C/D6]. These op-amps are used to route the signal
through the optional loudspeaker equalizer cards that can be installed on the ACM-1
motherboard. The presence of the EQ cards is detected automatically. If the EQ card is
plugged into its socket, the EQ1USED or EQ2USED at J6-6 or J7-6 [Sheet 2, B7] signal
is grounded causing U10 and/or U12 to route the audio signal through the EQ-cards, by
pulling the SW1A and SW2A signals at U10 or U12 low. Also, the appropriate section of
the green dual LED D50 [Sheet 2, A4] will be turned on to indicate the card is installed.
Further, the high-pass filter available on the EQ cards can be activated by setting switch
SW2 [Sheet 2, D7] to the correct position. This causes signal HF1 and HF2, which are
routed to the EQ cards via J6 and J7 [Sheet 2, B7] to be grounded.
After the signal is equalized, the audio signal is passed on to a second set of switchable
op-amps, U11 and U13 [C/D6]. The function of this op-amp pair is to set the mode of
operation of the amplifier: normal (stereo) mode, bridged mode or dual-mono mode. If
SW2B is high, the amplifier is in normal mode regardless of the state of the SW1B signal.
SW2B basically routes the signal of channel 1 into channel 2 if it is pulled low. By doing
this, the amplifier is configured in bridged mode or dual mono mode, depending on SW1B,
which inverts the signal going into channel 2, or not. When SW1B is high, the signal is not
inverted and the amplifier is in dual mono mode; if it is pulled low, the amplifier is in bridged
mode. The configuration of the mode of the amplifier is done by setting the SW1 to the
correct position [Sheet 2, D7].

9
THEORY OF OPERATION
The equalized signal is also routed to U7 [
C/
D6] which forms output line drivers. The
output of the EQ card is then available to link to the next amplifier, minimizing the need for
additional EQ cards. This signal is available at the female EQ output jacks P2 and P3
[C/D4] on the frontplate of the ACM-1 module. These outputs are also equipped with RFI
low-pass T-filters, diode clamps and spark-gaps. The output impedance at audio
frequencies is approximately 400 Ohms, making it possible to drive long cable lengths
without oscillation.
After the audio signals are equalized and composed in such a way as to set the correct
mode of the amplifier, they are routed into a software controlled attenuator U14 [D5]. With
this attenuator, the level of the audio signal can be attenuated in steps of 1 dB from 0 dB
all the way down to -100 dB. The lowest attenuation level is a full mute. The attenuation
level is set by the serial data stream IO9 (DATA) from the Neuron
®
. The attenuator is
addressed with I07 (ENABLE) with the timing signal supplied by IO8 (CLOCK), which is
generated by the Neuron. The 3.16 k Ohms resistors R40, 41, and 42, protect U14 from
damage when the ACM-1 is in standby mode. In this mode, the attenuator is off, but the
Neuron is still powered. The quad-NAND U21 [Sheet 2, C4/5] generates VCLK from the
ENABLE and CLOCK signal. This logic is used by the TC9412F attenuator. After the
level is set with the attenuator, signal buffer U8 [C/D4] routes the signal out through J1
pins 16 and 20 [Sheet 2, B7] to the power stages of the amplifier.
Monitoring and control, digital section:
Refer to the ACM-1 Schematic Diagram, Sheet 1 of 2, for the following information.
The monitoring and control of the amplifier is performed by the plug-in LonWorks
®
Neuron
module (not shown on schematic) which plugs into the ACM-1 motherboard at J9 and J10
[Sheet 2, A/B7]. This module incorporates a network transceiver which is connected to the
system's control network by means of RJ-45 connectors J12 and J13 [Sheet 2, D4],
which are located on the daughterboard.
The Neuron module switches the amplifier to operate mode by pulling low the IO6 signal
on transistor Q1 [Sheet 2, A4]. This transistor causes current to flow into the opto coupler,
located inside the amplifier which fires the TRIAC in the amplifier's power supply. Refer to
the 1600VI/1800VI service manual, Bose
®
part number 199747, for more information on
the amplifiers.
Each Neuron module is assigned its own unique identification number when it is
manufactured. It can only be activated and controlled by this unique address. If the
address number for a Neuron module is lost, the unit can identify itself on the network by
toggling its service pin. This pin is connected to the momentary switch on the front-panel
of the ACM-1 module. When this switch is depressed, the SERV pin is grounded and the
yellow LED lights up. The LED is also used to indicate network activity in the ACM-1. In
this mode the LED is lit constantly. The LED blinks with a 50% duty-cycle when the
neuron module is not yet configured on the network.
The amplifier is equipped with an LED on the front of the amplifier, located in the center of
the front panel, used to indicate network activity. It is triggered by Q4 [Sheet 2, A4], which
is turned on and off via the IO5 pin from the Neuron's micro-processor.
The Neuron gets its status information via the Analog to Digital Converter U9 [B3]. This is
a serial 10-bit ADC with 8 inputs. It communicates with the Neuron on the same DATA
line. The serial timing is delivered via the IO8 CLOCK signal and the IO1 signal which
basically functions as a control signal (the control clock for successive approximation
circuitry inside the chip) for the ADC. IO0 toggles the chip select pin and the output
enable pin. When they are both low, the falling edge of the IO8 shifts out the conversion
data out of the output pin connected to IO10. IO9 shift serial data into the converter. For
detailed timing information, consult the National Semiconductor datasheet on the ADC1038.

10
THEORY OF OPERATION
The AD
C
inputs are all equipped with diode clamps to protect its inputs from damage due
to a 15V input signal. This failure could occur if one of the components connected to the
ADC fails and shorts one of the 15V rails to the inputs. The resistors on the inputs of the
ADC protect the input stages of the converter against excessive currents due to fault
signals.
Six of the inputs directly sample six status signals. The other two are connected to a dual
4 channel multiplexer U17 [C1] which makes it possible to sample eight more different
status signals. V1_PEAK, V2_PEAK, V1_MEAN, V2_MEAN, I1_MEAN and I2_MEAN are
the mean and peak voltage and current levels directly measured at the output of the
power amplifier. With these signals, output signal levels can be displayed and the load
impedances can be calculated and used in the User Interface(s) connected via the
network.
The peak and mean output voltage levels are generated with U1, U2 and U3. U1 [C7]
divides down the +IOUT1 80 Vpk signal from the amplifier's output. After this, the signal
undergoes double sided rectification. From the rectified signal, the mean voltage is created
by a RC filter section, N14 [C6] and C24 [C6] and buffered with an op-amp. The
V1_MEAN output is taken from U1 pin 14 [C6]. In another op-amp stage, U3 [C5], the
peak signal is derived with a peak-hold circuit. The peak level is stored in C28 [B5].
V1_PEAK is taken off of U3 at Pin 7 [C5]. +IOUT2 is processed in the same way using
U2 and U3.
The mean current level is generated with U4 and U5 [A5-7]. Because the output current is
measured across the 20 milliOhm resistor that is installed inside the amplifier, the signal
needs to be divided down before it is routed into the balanced input stage formed by U4
and U5. The division is done by the 5 kOhms resistor arrays N16-19 [A/B7]. After
converting the signal into an unbalanced signal, the signal is double sided rectified. RC
filters R5/C26 [A5] and R6/C27 [A5] filter the signal and produce the scaled mean of the
output current for both amplifiers. U4 and U5 buffer this signal before it is routed into the
ADC [B3].
The dual multiplexer U17 together with U6 [C1] produce two extra buffered signals which
are routed into the remaining two inputs of the ADC. With the multiplexer, the Neuron
®
can
select which parameter should be sampled. These parameters are connected to the 8
inputs of the mutiplexer and can be selected with IO2A and IO3A. These 2 signals are
level shifted to +15V and inverted with transistors Q2 and Q3 [Sheet 2, A5]. Two inputs
are selected at the same time and fed to the ADC. XTEMP is the temperature on the ACM-
1 motherboard and is generated with temperature sensor U20 [C2]. 316ADD1 and
316ADD2 are generated by the amplifier and indicate that the relays at the outputs of the
amplifier are open due to a short circuit condition or due to DC offset caused by amplifier
failure. These signals are also supplied to the User Interface(s) to indicate that impedance
measurement is then invalid due to the opened relays.
The 106VDC (1800VI), 90VDC (1600VI) signal indicates the presence of the power
amplifier rail voltage. It is a divided down version of the rail voltage, and is used by the
User Interface(s) to detect proper operation of the amplifier.
THERM1 and THERM2 are voltages generated by the temperature sensors on the power
amplifier stage's heatsinks. With these scaled voltages the temperature of these stages
can be measured and displayed on the User Interface.
STDBYOK is the voltage derived from the standby power from the mains adapter or the
network. It is used to indicate if the amplifier can be turned back on after it is powered
down.