Category: Audio System Repair and Service
Contents of this article
- Test procedures
- Disassembling procedure
- Air leak test procedure
BOSE LS235
System Level Test
Test setup procedure
Set up the bass module to receive TAP commands. Reference “Setting up a Computer to Issue TAP Commands” and “Issuing TAP Commands to the Bass Module”. A digital audio input is required. Connect the analog output of an oscillator to the left analog input of an Analog to Digital (A-D) converter. Connect the test cable’s RCA connector to the A-D converter S/PDIF output. (The TAP command “SO ALL DL” issued in the omnibus.ttl macro set the system to send left channel information to all outputs) Using a system array cable part number 331294- 0010 or -0020, create the cube output test cable.
1. Check for S/PDIF, EQ Setting, Software Version
1.1 Issue the TAP command “ST S”. The bass module should respond similar to the following.
>ST S
SAMPLE RATE: 44102.34
SPKR TYPE :02
LCRB_MUTE :0
LSRS_MUTE :0
SPDIFE# :00000000
SERIAL# :1234567890ABCDEFG
>
Sample Rate: 44100 Hz + 2%
1.2 Issue the TAP command “TN 4”. The bass module should respond similar to the following. 012345678,010201
The first number is the checksum and the second is the firmware version. The latest software version is posted on serviceops.bose.
2. Thermistor Test
2.1 Issue the TAP command “ST T”. The bass modules should respond similar to the following.
>ST T
Rev : 010100
BassThrm : 0.6992
PS Thrm : 0.6914
BasAThrm : 0.4961
Rate : 192012.56
SPDIFE# : 00000000
Set up the bass module to receive TAP commands. Reference “Setting up a Computer to Issue TAP Commands” and “Issuing TAP Commands to the Bass Module”. A digital audio input is required. Connect the analog output of an oscillator to the left analog input of an Analog to Digital (A-D) converter. Connect the test cable’s RCA connector to the A-D converter S/PDIF output. (The TAP command “SO ALL DL” issued in the omnibus.ttl macro set the system to send left channel information to all outputs) Using a system array cable part number 331294- 0010 or -0020, create the cube output test cable.
1. Check for S/PDIF, EQ Setting, Software Version
1.1 Issue the TAP command “ST S”. The bass module should respond similar to the following.
>ST S
SAMPLE RATE: 44102.34
SPKR TYPE :02
LCRB_MUTE :0
LSRS_MUTE :0
SPDIFE# :00000000
SERIAL# :1234567890ABCDEFG
>
Sample Rate: 44100 Hz + 2%
1.2 Issue the TAP command “TN 4”. The bass module should respond similar to the following. 012345678,010201
The first number is the checksum and the second is the firmware version. The latest software version is posted on serviceops.bose.
2. Thermistor Test
2.1 Issue the TAP command “ST T”. The bass modules should respond similar to the following.
>ST T
Rev : 010100
BassThrm : 0.6992
PS Thrm : 0.6914
BasAThrm : 0.4961
Rate : 192012.56
SPDIFE# : 00000000
2.2 Verify the results are within the following limits.
BassThrm: Limit: 0.65+/- 0.08
BassThrm : 0.6992 Limit: 0.3< BassThrm< 0.8
PS Thrm : 0.6914 Limit: 0.3< PS Thrm < 0.8
3. PSC Test (Power Supply Control)
3.1 Issue the TAP command “PS MAX”. Wait 250ms. Issue the TAP command “TN5”.
3.2 Verify the response is “PS Passed”.
4. Bass Module Frequency Sweep Test
4.1 Apply a 200mVrms, 100 Hz signal to the bass module.
4.2 Sweep the oscillator from 40 Hz to 300 Hz.
Note: No extraneous noises such as rubbing, scraping or ticking should be heard. To distinguish between normal suspension noise, rubs and ticks, displace the woofer cone with your finger. If the sound can be made to go away or get worse, it’s a rub or tick and the woofer should be replaced. If the noise stays the same, it’s normal suspension noise and it will not be heard with regular program material.
5. Air Leak Test
5.1 Apply a 200mVrms, 40 Hz signal to the bass module. Check for air leaks from the cabinet particularly from where the SPS PCB EMI can mounts to the cabinet.
6. Cube Output Test
6.1 Apply a 1 kHz, 125 mVms signal to the bass module.
6.2 Set the bass module to bypass mode by issuing the TAP command “BY ALL”. This bypasses the system signal processing.
6.3 Measure each of the cube outputs and ensure they are > 1Vrms.
BassThrm: Limit: 0.65+/- 0.08
BassThrm : 0.6992 Limit: 0.3< BassThrm< 0.8
PS Thrm : 0.6914 Limit: 0.3< PS Thrm < 0.8
3. PSC Test (Power Supply Control)
3.1 Issue the TAP command “PS MAX”. Wait 250ms. Issue the TAP command “TN5”.
3.2 Verify the response is “PS Passed”.
4. Bass Module Frequency Sweep Test
4.1 Apply a 200mVrms, 100 Hz signal to the bass module.
4.2 Sweep the oscillator from 40 Hz to 300 Hz.
Note: No extraneous noises such as rubbing, scraping or ticking should be heard. To distinguish between normal suspension noise, rubs and ticks, displace the woofer cone with your finger. If the sound can be made to go away or get worse, it’s a rub or tick and the woofer should be replaced. If the noise stays the same, it’s normal suspension noise and it will not be heard with regular program material.
5. Air Leak Test
5.1 Apply a 200mVrms, 40 Hz signal to the bass module. Check for air leaks from the cabinet particularly from where the SPS PCB EMI can mounts to the cabinet.
6. Cube Output Test
6.1 Apply a 1 kHz, 125 mVms signal to the bass module.
6.2 Set the bass module to bypass mode by issuing the TAP command “BY ALL”. This bypasses the system signal processing.
6.3 Measure each of the cube outputs and ensure they are > 1Vrms.
PCB Level Performance Verification Tests
Test Setup
Set up the bass module to receive TAP commands. Refer Setting up a Computer to Issue TAP Commands and Issuing TAP Commands to the Bass Module. Remove the DSP and SPS PCB from the cabinet. Reconnect the DSP PCB and SPS PCB while outside the cabinet. Leave the DSP assembled to the heat sink. Refer to the disassembly procedures.
1. DSP Status Check
Issue the TAP command “ST S” . Typical response shown below.
>ST S
SAMPLE RATE: 192015.67
SPKR TYPE :02
LCRB_MUTE :0
LSRS_MUTE :0
SPDIFE# :00000000
SERIAL# :1234567890ABCDEFG
Issue the TAP command “ST T”. Typical response
shown below.
>ST T
Rev : 010100
BassThrm : 0.6992
PS Thrm : 0.6914
BasAThrm : 0.4961
Rate : 192012.56 (S/PDIF Sample Rate)
SPDIFE# : 00000000 (S/PDIF Error Rate)
Rev : 010100 (Software version)
BassThrm: Limit 0.65 + 0.8 (A/D converters)
PS Thrm: Limit 0.65 + 0.8 (A/D converters)
BasAThrm: Limit 0.60 + 0.13 (A/D converters)
Rate : (S/PDIF Sample Rate)
SPDIFE#: should be 0 - error count reset during
“STS” command (S/PDIF Error Rate)
Verify the results are within the following limits.
BassThrm: Limit 0.3 <Bass Thrm <0.8
PS Thrm: Limit 0.3 <PS Thrm <0.8
Set up the bass module to receive TAP commands. Refer Setting up a Computer to Issue TAP Commands and Issuing TAP Commands to the Bass Module. Remove the DSP and SPS PCB from the cabinet. Reconnect the DSP PCB and SPS PCB while outside the cabinet. Leave the DSP assembled to the heat sink. Refer to the disassembly procedures.
1. DSP Status Check
Issue the TAP command “ST S” . Typical response shown below.
>ST S
SAMPLE RATE: 192015.67
SPKR TYPE :02
LCRB_MUTE :0
LSRS_MUTE :0
SPDIFE# :00000000
SERIAL# :1234567890ABCDEFG
Issue the TAP command “ST T”. Typical response
shown below.
>ST T
Rev : 010100
BassThrm : 0.6992
PS Thrm : 0.6914
BasAThrm : 0.4961
Rate : 192012.56 (S/PDIF Sample Rate)
SPDIFE# : 00000000 (S/PDIF Error Rate)
Rev : 010100 (Software version)
BassThrm: Limit 0.65 + 0.8 (A/D converters)
PS Thrm: Limit 0.65 + 0.8 (A/D converters)
BasAThrm: Limit 0.60 + 0.13 (A/D converters)
Rate : (S/PDIF Sample Rate)
SPDIFE#: should be 0 - error count reset during
“STS” command (S/PDIF Error Rate)
Verify the results are within the following limits.
BassThrm: Limit 0.3 <Bass Thrm <0.8
PS Thrm: Limit 0.3 <PS Thrm <0.8
The bass module requires a digital audio input. Connect the analog output of an oscillator to the analog input of an Analog to Digital (A-D) converter. Connect the test cable’s RCA connector to the A-D converter S/PDIF output. Outputs are not loaded unless specified. To deliver a signal to all 6 amplifier channels the signal should be encoded on the left S/PDIF channel. Issue TAP commands
“SP 5”
“BY ALL”
“SO ALL DL”
Caution: Before handling the Power Supply PCB (SPS) PCB after power has been removed, connect a 1K, 5W resistor across C110 and then across C111 for 2 seconds to discharge the two caps. C110 and C111 must be discharged before the board can be safely handled. Failure to discharge the caps could result in electrical shock.
2. Mid Frequency Gain, All Channels
2.1 Apply a 1Vrms, 400 Hz SPDIF signal to the bass module.
2.2 Measure the amplifier outputs according to the following table.
“SP 5”
“BY ALL”
“SO ALL DL”
Caution: Before handling the Power Supply PCB (SPS) PCB after power has been removed, connect a 1K, 5W resistor across C110 and then across C111 for 2 seconds to discharge the two caps. C110 and C111 must be discharged before the board can be safely handled. Failure to discharge the caps could result in electrical shock.
2. Mid Frequency Gain, All Channels
2.1 Apply a 1Vrms, 400 Hz SPDIF signal to the bass module.
2.2 Measure the amplifier outputs according to the following table.
Measurement Point
|
Measurement
|
LC Output
|
8.5 Vrms ±10%
|
RC Output
|
8.5 Vrms ±10%
|
LS Output
|
8.5 Vrms ±10%
|
RS Output
|
8.5 Vrms ±10%
|
Bass Output – J108
|
8.5 Vrms ±10%
|
Note: J108 is located on the power supply PCB
3. Mute, All Channels
3.1 Apply a 1Vrms, 400 Hz SPDIF signal to the bass module.
3.2 Issue the TAP command “MU AMP ON” to place the amplifiers in the muted state.
3.3 Measure the amplifier outputs according to the following table.
3.4 When complete, issue the TAP command “MU AMP OFF” to unmute the amps.
3.1 Apply a 1Vrms, 400 Hz SPDIF signal to the bass module.
3.2 Issue the TAP command “MU AMP ON” to place the amplifiers in the muted state.
3.3 Measure the amplifier outputs according to the following table.
3.4 When complete, issue the TAP command “MU AMP OFF” to unmute the amps.
Measurement Point
|
Measurement
|
LC Output – RCA
|
< 1 mVrms
|
RC Output – RCA
|
< 1 mVrms
|
LS Output – RCA
|
< 1 mVrms
|
RS Output – RCA
|
< 1 mVrms
|
Bass Output – J108
|
< 1 mVrms
|
Note: J108 is located on the power supply PCB
4. Satellite High Frequency Gain
4.1 Apply a 1Vrms, 15 kHz sine wave audio signal via the S/PDIF input.
4.2 Measure the amplifier outputs according to the following table.
4.1 Apply a 1Vrms, 15 kHz sine wave audio signal via the S/PDIF input.
4.2 Measure the amplifier outputs according to the following table.
Measurement Point
|
Measurement
|
LC Output – RCA
|
8.0 Vrms ±10%
|
RC Output – RCA
|
8.0 Vrms ±10%
|
LS Output – RCA
|
8.0 Vrms ±10%
|
RS Output – RCA
|
8.0 Vrms ±10%
|
5. Satellite Low Frequency Gain
5.1 Apply a 1Vrms, 100 Hz sine wave audio signal via the S/PDIF input.
4.2 Measure the amplifier outputs according to the following table
4.2 Measure the amplifier outputs according to the following table
Measurement Point
|
Measurement
|
LC Output – RCA
|
8.0 Vrms ±10%
|
RC Output – RCA
|
8.0 Vrms ±10%
|
LS Output – RCA
|
8.0 Vrms ±10%
|
RS Output – RCA
|
8.0 Vrms ±10%
|
6. Bass Low Frequency Gain
6.1 Apply a 1Vrms, 30 Hz sine wave audio signal via the S/PDIF input.
6.2 Measure the bass output at J108. It should be 8.0Vrms + 10%.
7. DC Offset, All Channels
7.1 Short the analog inputs to the D/A converter.
7.2 Measure the amplifier outputs according to the following table.
6.2 Measure the bass output at J108. It should be 8.0Vrms + 10%.
7. DC Offset, All Channels
7.1 Short the analog inputs to the D/A converter.
7.2 Measure the amplifier outputs according to the following table.
Measurement Point
|
Measurement
|
LC Output – RCA
|
< 70 mVdc
|
RC Output – RCA
|
< 70 mVdc
|
LS Output – RCA
|
< 70 mVdc
|
RS Output – RCA
|
< 70 mVdc
|
Bass Output – J108
|
< 25 mVdc
|
Note: J108 is located on the power supply PCB
8. Satellite Channel Small Signal Distortion
8.1 Connect a 8 Ohm, 1/2 watt resistor to the amplifier output being tested.
8.2 Apply a 6.0 kHz signal at a level to obtain 1/10 watt output at each channel (0.89 volts measured across the 8 ohm load).
8.3 Measure the amplifier outputs with a 30 kHz LPF
8.1 Connect a 8 Ohm, 1/2 watt resistor to the amplifier output being tested.
8.2 Apply a 6.0 kHz signal at a level to obtain 1/10 watt output at each channel (0.89 volts measured across the 8 ohm load).
8.3 Measure the amplifier outputs with a 30 kHz LPF
Measurement Point
|
Measurement
|
LC Output – RCA
|
< 0.2% THD+N
|
RC Output – RCA
|
< 0.2% THD+N
|
LS Output – RCA
|
< 0.2% THD+N
|
RS Output – RCA
|
< 0.2% THD+N
|
9. Satellite Channel Large Signal Distortion
9.1 Connect a 8 Ohm, 20 watt resistor to the amplifier output being measured. Load only one channel at a time.
9.2 Apply a 1.0 kHz signal at a level to obtain 10 watt output at each channel (8.9 volts measured across the 8 ohm load).
9.3 Measure the amplifier outputs with a 30 kHz LPF.
9.2 Apply a 1.0 kHz signal at a level to obtain 10 watt output at each channel (8.9 volts measured across the 8 ohm load).
9.3 Measure the amplifier outputs with a 30 kHz LPF.
Measurement Point
|
Measurement
|
L Output – RCA
|
< 0.1% THD+N
|
R Output – RCA
|
< 0.1% THD+N
|
LS Output – RCA
|
< 0.1% THD+N
|
RS Output – RCA
|
< 0.1% THD+N
|
10. Bass Channel Small Signal Distortion
10.1 Connect a 8 Ohm, 1/10 watt resistor to the amplifier output being measured.
10.2 Apply a 300 Hz signal at a level to obtain 1/10 watt output at the bass channel output J108 (0.89 volts measured across the 8 ohm load).
10.3 Measure the bass channel output at J108. It should measure <0.2% THD+N
11. Bass Channel Large Signal Distortion
11.1 Connect a 8 Ohm, 20 watt resistor to the amplifier output being measured.
11.2 Apply a 100 Hz signal at a level to obtain 10 watt output at the bass channel output J108 (8.9 volts measured across the 8 ohm load).
11.3 Measure the bass channel output at J108. It should measure <0.2% THD+N
Caution: Remove power. If handling the SPS PCB, connect a 1K, 5W resistor across C110 and then across C111 for 2 seconds to discharge the two caps. C110 and C111 must be discharged before the board can be safely handled. Failure to discharge the caps could result in electrical shock.
10.2 Apply a 300 Hz signal at a level to obtain 1/10 watt output at the bass channel output J108 (0.89 volts measured across the 8 ohm load).
10.3 Measure the bass channel output at J108. It should measure <0.2% THD+N
11. Bass Channel Large Signal Distortion
11.1 Connect a 8 Ohm, 20 watt resistor to the amplifier output being measured.
11.2 Apply a 100 Hz signal at a level to obtain 10 watt output at the bass channel output J108 (8.9 volts measured across the 8 ohm load).
11.3 Measure the bass channel output at J108. It should measure <0.2% THD+N
Caution: Remove power. If handling the SPS PCB, connect a 1K, 5W resistor across C110 and then across C111 for 2 seconds to discharge the two caps. C110 and C111 must be discharged before the board can be safely handled. Failure to discharge the caps could result in electrical shock.
12. Speaker Variant
A replacement DSP PCB will be set to the proper speaker variant but there will be no serial number stored. To store a serial number, perform the following.
12.1 Issue TAP command SE C,SERIAL#,ON.
12.2 Issue TAP command ST S. Ensure the speaker type is 10.
A similar reply would be:
SAMPLE RATE: 44102.34
SPKR TYPE :10
LCRB_MUTE :0
LSRS_MUTE :0
SPDIFE# :00000000
SERIAL# :1234567890ABCDEFG
Disassembly Procedures
A replacement DSP PCB will be set to the proper speaker variant but there will be no serial number stored. To store a serial number, perform the following.
12.1 Issue TAP command SE C,SERIAL#,ON.
12.2 Issue TAP command ST S. Ensure the speaker type is 10.
A similar reply would be:
SAMPLE RATE: 44102.34
SPKR TYPE :10
LCRB_MUTE :0
LSRS_MUTE :0
SPDIFE# :00000000
SERIAL# :1234567890ABCDEFG
Set up a Computer to Issue Tap Commands
1. Set up the Terminal Emulator
1.1 Download the terminal emulator TeraTerm from the Lifestyle 235 Bass Module product page located on the service web site serviceops.bose
1.2 Setup a terminal emulator.
1.1 Download the terminal emulator TeraTerm from the Lifestyle 235 Bass Module product page located on the service web site serviceops.bose
1.2 Setup a terminal emulator.
Issuing TAP Commands to the Bass Module
Items Needed
1. TeraTerm terminal emulator - download from PS18/28/35/38/48 III product page - serviceops.bose
2. PC3macro.zip files - download from PS18/28/35/38/48 III product page -serviceops.bose
3. RS232-TTL Converter - B&B electronics Model 232LPTTL or similar - bb-elec.
4. TAP cable part number 299656 - order from Bose
1. TeraTerm terminal emulator - download from PS18/28/35/38/48 III product page - serviceops.bose
2. PC3macro.zip files - download from PS18/28/35/38/48 III product page -serviceops.bose
3. RS232-TTL Converter - B&B electronics Model 232LPTTL or similar - bb-elec.
4. TAP cable part number 299656 - order from Bose
1. Download Macros
1.1 Download the file ps3macro.zip from the PS18/28/35/38/48 III product page located on the service web site - serviceops.bos. Unzip the files and place them in the folder where your terminal emulator is located .
1.2 Open TeraTerm and set it as described on the previous page - Setting up a Computer to Issue TAP Commands.
1.3 Connect TAP cable part number 299656 to a computer and the bass module. A RS232-TTL converter is needed to connect to the computer- B&B electronics Model 232LPTTL or similar -bb-elec. To simulate a turn on signal, connect a 9 Volt battery to the TAP cable’s 9 Volt battery connector.
1.4 In the TeraTerm tools menu, select Control. Scroll down to Macro.
1.5 In the Open Macro window, select the omnibus.ttl macro and click Open. The bass module is now ready to receive further TAP commands.
1.1 Download the file ps3macro.zip from the PS18/28/35/38/48 III product page located on the service web site - serviceops.bos. Unzip the files and place them in the folder where your terminal emulator is located .
1.2 Open TeraTerm and set it as described on the previous page - Setting up a Computer to Issue TAP Commands.
1.3 Connect TAP cable part number 299656 to a computer and the bass module. A RS232-TTL converter is needed to connect to the computer- B&B electronics Model 232LPTTL or similar -bb-elec. To simulate a turn on signal, connect a 9 Volt battery to the TAP cable’s 9 Volt battery connector.
1.4 In the TeraTerm tools menu, select Control. Scroll down to Macro.
1.5 In the Open Macro window, select the omnibus.ttl macro and click Open. The bass module is now ready to receive further TAP commands.
Check if the bass module is ready to receive TAP by issuing the TAP command ST S.
Type:
ST S
Press Return
A similar reply would be:
SAMPLE RATE: 44102.34
SPKR TYPE :10
LCRB_MUTE :0
LSRS_MUTE :0
SPDIFE# :00000000
SERIAL# :1234567890ABCDEFG
Note: There are three files in ps3macro.zip. The macro file omnibus.ttl sends the following commands enter TAP, select 5 speaker mode, bypass all processing, send left input to all channels, set volume to max, unmute the DSP, and unmute the power amps. The two .INI files set the TeraTerm terminal emulator program. All three files should be placed in the same folder as the TeraTerm program.Type:
ST S
Press Return
A similar reply would be:
SAMPLE RATE: 44102.34
SPKR TYPE :10
LCRB_MUTE :0
LSRS_MUTE :0
SPDIFE# :00000000
SERIAL# :1234567890ABCDEFG
Disassembly Procedures
1. Front Cover Removal
1.1 Remove the four screws indicated. Pull off the front cover.
Note: The DSP PCB is attached to the front panel. Cables from the Power Supply (SPS) PCB attach to the DSP PCB.
1.1 Remove the four screws indicated. Pull off the front cover.
Note: The DSP PCB is attached to the front panel. Cables from the Power Supply (SPS) PCB attach to the DSP PCB.
1.2 Remove the connectors from the DSP PCB.
Important Note: When replacing the front cover, twist the foam wrapped cable as shown to ensure when assembled, the cable is poistioned away from the area of the PCB where the MOV is located.
Important Note: When replacing the front cover, twist the foam wrapped cable as shown to ensure when assembled, the cable is poistioned away from the area of the PCB where the MOV is located.
2. DSP PCB Removal
2.1 Perform procedure 1.
2.2 On the front cover connection panel, remove the three screws indicated.
2.3 Remove the three screws indicated securing the outputs to the heatsink. Lift out the DSP PCB.
2.1 Perform procedure 1.
2.2 On the front cover connection panel, remove the three screws indicated.
2.3 Remove the three screws indicated securing the outputs to the heatsink. Lift out the DSP PCB.
3. Steel Baffle Plate/ SPS Removal
3.1 Remove the six screws that secure the baffle to the cabinet.
Note: The SPS module is attached to this plate.
3.1 Remove the six screws that secure the baffle to the cabinet.
Note: The SPS module is attached to this plate.
4. Cube Grille and Twiddler Removal
4.1 At the points indicated, use the tips of your fingers to release the Bose® logo and slide it off.
4.1 At the points indicated, use the tips of your fingers to release the Bose® logo and slide it off.
4.2 Remove the screw indicated.
4.3 Using a pointed tool, pull outward on the side of the grill to release the grill tabs from the cube housing. Once the side is released, the front grille tab can be released from the cube housing.
4.4 Remove the four screws from the driver you wish to remove.
4.5 Lift the driver out of the cabinet.
4.6 Record the color of the wires and terminal.
4.5 Lift the driver out of the cabinet.
4.6 Record the color of the wires and terminal.
