How it Works
Klipsch
Loading...
SW-12-I
Service manual
21 pgs534.04 Kb0

Klipsch SW-12-I, SW-15-I Service manual

SERVICE MANUAL
Subwoofer Amplifier Model:
SW12-I SW15-I
KLIPSCH, INC.
Klipsch Subwoofer Amplifier Service Manual KSAMM-002a
TABLE OF CONTENTS
SPECIFICATIONS .......................................................................................................................................2
Model: SW12-I ...........................................................................................................................................2
Model: SW15-I ...........................................................................................................................................2
INPUTS ...................................................................................................................................................... 3
SIGNAL CONDITIONING ......................................................................................................................... 3
COMPRESSION......................................................................................................................................... 3
DRIVER CIRCUIT ..................................................................................................................................... 3
OUTPUT .................................................................................................................................................... 3
OTHER FEATURES................................................................................................................................... 4
Model: SW12-I .......................................................................................................................................... 5
Model: SW15-I .......................................................................................................................................... 6
SW15 PARTS LIST.................................................................................................................................... 12
SCHEMATICS ........................................................................................................................................... 15
Model: SW12-I ........................................................................................................................................ 15
Model: SW15-I ........................................................................................................................................ 18
Page 1
Klipsch Subwoofer Amplifier Service Manual KSAMM-002a
Specifications
Model: SW12-I
Input Sensitivity for max Rated Output: Line input 60mVrms @ 30Hz. Speaker input 700mVrms @ 30Hz. Maximum Rated Output: 150 Watts into 8 ohms. Max. Hum: 3.5mV @ 60Hz. Max. Distortion: 4% At Full Rated Output. Freq Response: 27 to 120Hz +0/-3dB w/12dB per Octave Rolloff. Bass Boost: +6dB Boost @ 30Hz. Low Pass Crossover: Variable from 40 - 120 Hz. 24 dB/Octave slope above 120 Hz. High Pass Crossover: Line outputs fixed at 80 Hz, 6dB/Octave slope. Speaker outputs fixed at 120 Hz, 6dB/Octave slope.
Model: SW15-I
Input Sensitivity for Max Rated Output: Line input 33mVrms @ 30Hz. Speaker input 900mVrms @ 30Hz. Maximum Rated Output: 200 Watts into 4 ohms. Max. Hum: 3.5mV @ 60Hz. Max. Distortion: 4% At Full Output. Freq Response: 27 to 120Hz +0/-3dB w/12dB per Octave Rolloff. Bass Boost: +6dB Boost @ 30Hz. Low Pass Crossover: Variable from 40 - 120 Hz. 24 dB/Octave slope above 120 Hz. High Pass Crossover: Line outputs fixed at 80 Hz, 6dB/Octave slope. Speaker outputs fixed at 120 Hz, 6dB/Octave slope.
Page 2
Klipsch Subwoofer Amplifier Service Manual KSAMM-002a
THEORY OF OPERATION
SW12, & SW15 Series I Amplifiers
INPUTS
There are two types of inputs and passive outputs. Four RCA jacks for LINE LEVEL left and right inputs and outputs and a panel of SPEAKER LEVEL inputs and outputs for left and right stereo channels. The SPEAKER LEVEL inputs have a high pass filter on each channel that allows frequencies above 120 Hz to go directly to the main speakers of the system. Frequencies below 120 Hz go through the subwoofer amplifier and on to the woofer. The LINE LEVEL inputs also use a high pass filter that allows frequencies above 80 Hz to go back out to a system amplifier. Frequencies below 80 Hz go through the subwoofer amplifier and on to the woofer. Both filters have a 6dB per octave rolloff.
SIGNAL CONDITIONING
The first op-amp of U1, a quad op-amp IC, is a summing amp for the RCA and SPEAKER level inputs. The LEVEL adjustment is located between the first and second op-amp stages of U1. The second op-amp of U1 is a buffer stage with a gain of 1. The third op-amp of U1 is a High pass filter configuration. The fourth op-amp of U1 is used to adjust phase from 0° to 180°. The next circuit is an adjustable RC filter for low pass filtering from 40Hz to 120Hz consisting of U2 and U4.
COMPRESSION
The compression circuit consists of U5, U6, and Q28 and is adjusted via R30. If adjusted correctly, this circuit will limit the amplitude of the signal so the minimum amount of distortion in the form of clipping will occur at the output of the amplifier. R34 is used to set the maximum output level for the amplifier so it doesn’t underamplify or clip. Next, the signal goes through a buffer amplifier U2, which provides a gain of 4. Then the signal goes on to the driver circuits.
DRIVER CIRCUIT
The driver circuit consists of Q1 through Q12 and is located on the Filter/Driver board. The driver circuit has a DC offset adjustment, R50, which should be set at 0 Vdc +/- 50mVdc. This can be measured across the + and - output wires (white & black respectively) from the amp with power on and no signal applied. The driver circuit is a Class AB amplifier.
OUTPUT
The output section of this amplifier uses discrete components Q15 through Q26 to obtain the high power output required. The output amplifier circuit is a Class AB complementary symmetry configuration with three sets of four transistors cascaded. This provides high power output into a low impedance load. The components for the output circuit is located on the Power Board.
POWER SUPPLIES
The main power supply circuit is unregulated and supplies +/- 81 Vdc for the output and driver circuits. The +/- 81 Vdc is then divided and regulated by 34V zener diodes to supply +/- 34 Vdc to bias the driver circuit. There is a second power supply which is fed by a second set of taps off of the transformer. This is the regulated +/- 15 Vdc for the op-amps on the filter board.
Page 3
Klipsch Subwoofer Amplifier Service Manual KSAMM-002a
OTHER FEATURES
This amplifier uses a control circuit to control the operation of the output relay. When power is first applied the circuit provides a delay before activating the relay. This is a protection feature to protect the speaker and amplifier from initial current surges. The circuit also provides protection from over-current conditions by de-activating the relay when excessive output current is sensed. The relay and it’s control circuitry is located on the Filter/Driver Board and consists of U11, U12, RLY 1 and R131. R131 is used to set the threshold level for over-current sensing.
Page 4
Klipsch Subwoofer Amplifier Service Manual KSAMM-002a
SW12-I AMPLIFIER ALIGNMENT PROCEDURE
CAUTION!
Lethal voltages are present and exposed when cover is off of amplifier.
1
Only qualified service technicians should attempt to repair or align subwoofer amplifiers.
Equipment required:
A signal source capable of supplying a 30Hz sine wave at 300mVrms. A true RMS Voltmeter such as the Fluke 8060B. A 16 ohm load rated for at least 200 Watts. An oscilloscope (optional).
To totally align SW12 series 1 amplifiers, follow this procedure:
1. Disconnect power from the UUT (unit under test).
2. Connect the UUT (unit under test) to a 16 ohm load.
3. Connect a signal generator to the RCA input of the amp.
4. Set all controls on the UUT to their full clockwise position.
5. Set the signal generator for 30Hz and 60mVrms output. (be sure and measure the output of the generator for 60mVrms.)
6. Connect the voltmeter leads to the output of the UUT.
7. Apply power to the UUT.
8. Adjust R34 for 33Vrms. Range is from 32.1 Vrms to 34 Vrms.
9. Change signal level to 1.5mVrms @ 30Hz .
10. Measure the output voltage. Should be between .94 Vrms and 1.06Vrms. Adjust R30 if necessary.
* NOTE: Some interaction between adjustments is common. Recheck steps 8 and 10 for
proper voltages.
11. Alignment of the UUT is now complete. Disconnect power and other connections from the UUT.
Page 5
Klipsch Subwoofer Amplifier Service Manual KSAMM-002a
SW15-I AMPLIFIER ALIGNMENT PROCEDURE
CAUTION!
Lethal voltages are present and exposed when cover is off of amplifier.
1
Only qualified service technicians should attempt to repair or align subwoofer amplifiers.
Equipment required:
A signal source capable of supplying a 30Hz sine wave at 300mVrms. A true RMS Voltmeter such as the Fluke 8060B. A 16 ohm load rated for at least 300 Watts. An oscilloscope (optional).
To totally align SW15 series 1 amplifiers, follow this procedure:
1. Disconnect power from the UUT (unit under test).
2. Connect the UUT (unit under test) to a 16 ohm load.
3. Connect a signal generator to the RCA input of the amp.
4. Set all controls on the UUT to their full clockwise position.
5. Set the signal generator for 30Hz and 33mVrms output. (be sure and measure the output of the generator for 33mVrms.)
6. Connect the voltmeter leads to the output of the UUT.
7. Apply power to the UUT.
8. Adjust R34 for 29.5Vrms. Range is from 29.1Vrms to 30.1Vrms.
9. Change signal level to 1.5mVrms @ 30Hz .
10. Measure the output voltage. Should be between 1.19 Vrms and 1.33Vrms. Adjust R30 if necessary.
* NOTE: Some interaction between adjustments is common. Recheck steps 8 and 10 for
proper voltages.
11. Alignment of the UUT is now complete. Disconnect power and other connections from the UUT.
Page 6
Loading...
+ 14 hidden pages
Buy Points How it Works FAQ Contact Us Questions and Suggestions Privacy Policy Cookie Policy Terms of Use