BOSE ACM-1 Service Manual
ACM-1 Amplifier Control Module
®
®
©
1999 Bose Corporation
Service Manual
Part Number 199746 Rev. 00
CONTENTS
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
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.
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.
2
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.
3
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.
4
GND
IN1+
IN1-
IN2+
IN2-
GND
A
Circuitry
2
Unbalanced
Figure 1. ACM-1 Audio Section Block Diagram
Mode Switch
SW1A SW1B MODE
0
011 1
don't care
don't care
Truth Table
bridged
0
dual mono
normal
normal
SW2B
SW1B
Protection
3
Balanced
U16
6
A
Protection
Circuitry
HF Switch
5
2
0
U10
Selector
2
3
U15
Balanced
Unbalanced
6
1
SW1A
SW2
HF2
Eq Card 2
2
7
0
1
Selector
U12
5
2
U13
1
7
Selector
SW2A
1
Switchable
Inverter
U11
5
1
SW1B
SW2B
HF1
J6-4
Eq Card 1
J6-5
7
1
2
A
5
Buffer
Driver
U7
7
Protection
Circuitry
CH. 2 EQ
OUTPUT
5
21
U14
22
5
Buffer
Driver
U8
7
Protection
Circuitry
P2
J1-20
AMP IN 2
ENABLE I07
Attenuator
0 -100 dB
Digital
12
14
8VCLK
Clock Logic
U21
4
3
13
A
3
Buffer
Driver
U7
1
Protection
Circuitry
CH. 1 EQ
OUTPUT
P3
DATA I08
3
Buffer
Driver
U8
1
Protection
Circuitry
J1-16
AMP IN 1
5
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
I Out +1
Rectification
Network Power (dc / dc)
Adapter Power (ac / dc)
Amplifier Power (dc)
Mean
Peak
V1_Mean
V1_Peak
Jumper
Standby
Wired 'OR'
D
Rectifier
Thermal
Sensor
Therm 1
Therm 2
106 dc
Standby
Protect 1
Protect 2
Regulator
A
Multiplexer
+5Vdc
Gnd.
V1_Mean
V1_Peak
V2_Mean
V2_Peak
I1_Mean
I2_Mean
Aux 1
Aux 2
Signals to Amplifier
Amp In 1
Amp In 2
Power-up
LED
Analog to Digital
Converter
10-bit Serial
6
I Out +2
I Out 1+
I Out 1-
I Out 2+
I Out 2-
Rectification
Current
Sense
Divider
Current
Sense
Divider
Mean
Peak
V2_Mean
V2_Peak
Rectification Mean
Rectification Mean
Figure 2. ACM-1 Monitoring Section Block Diagram
I1_Mean
I2_Mean
Level Shifting
Power-up
Data Bus
Neuron
Micro-
processor
Network (LonWorks®)
Service LED
Service Pin
Amplifier
Data
Activity
LED
Network Power
Gnd.
G
eneral Description:
THEORY OF OPERATION
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
standard which is a registered trademark of Echelon
the amplifier(s) may be a personal computer or any other 'smart' device that incorporates
a LonWorks
Neuron® module.
®
Corporation. The device controlling
®
network
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 flashmemory. 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 daughterboard 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.
7
THEORY OF OPERATION
Power Supply Section:
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
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 ACM1 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.
®
module [not shown on
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].
8
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
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 attenuator is
The monitoring and control of the amplifier is performed by the plug-in LonWorks
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
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.
®
part number 199747, for more information on
®
Neuron
9
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