Infinity Bu-1 (CMS-1) – Powered sub-woofer – schematic - testing

Specifications
Dimensions
Inches . . . . . . . . . . . . . . . . 11½ x 11½ x 11½"
Metric . . . . . . . . . . . . . . . . 29.2 x 29.2 x 29.2cm plus 1¼" (32mm) for feet.
Driver . . . . . . . . . . . . . . . . 8" Woofer
Nominal Impedance . . . . . . . . . . . . 4 
Enclosure Design. . . . . . . . . . . . . Tuned Port
Amplifier Power . . . . . . . . . . . . . 50 watts RMS
Frequency Response . . . . . . . . . . . 45Hz - 150Hz (± 3dB)
Crossover Frequency . . . . . . . . . . . 50 to 150 Hz Continuously Variable

1. Auto Power - This Auto On/Off switch controls whether the BU1’s Automatic turn-on circuit is active. When the switch is ON , the BU1 will turn itself on, indicated by a green LED, when it is plugged in and receiving a signal. When the BU1 has not received a signal for approximately ten minutes, the unit will revert to the STANDBY mode, indicated by a red LED. When this switch is OFF, the unit will revert to the STANDBY mode and will stay OFF, regardless of input signal. THIS IS NOT A TRUE AC POWER SWITCH AS IT DOES NOT DISCONNECT THE AMPLIFIER FROM THE 120VAC LINE.
2. High Level Inputs - These High Level Inputs are for receivers that do not have line-level “pre-amp out” or “subwoofer out” jacks. When a pair of main or satellite speakers are attached to the OUTPUT terminals, they are driven the full range of frequencies as generated by the music source (receiver, amplifier, etc.)

3. Low Level Input - These left and right Line Level Inputs are normally used when the receiver/processor has line-level “pre-amp out ” or “subwoofer out” jacks. If a single cable mono or subwoofer source is connected to the BU1, a Y-cable must be connected to the subwoofer for full output.
4. Volume Control - This controls the volume level of the subwoofer.
5. Frequency - The Frequency adjustment determines the upper corner roll-off point for the BU1.

Schematic

TEST PROCEDURE

Equipment needed: Function/signal generator/sweep generator

Integrated Amplifier

Multimeter

Cables - line level (RCA) and speaker cables

General Function UUT = Unit Under Test

1. Connect both right and left line level inputs (RCA) to signal generator and UUT. Use Y-cable if necessary from mono source. VOLUME control should be full counterclockwise.

2. Turn on generator, adjust to 25mV, 50 Hz.

3. Plug in UUT; red LED should be ON. Turn VOLUME control full clockwise.

4. LED should turn Green; immediate bass response should be heard and felt from port tube opening.

5. Turn off generator, turn VOLUME control fully counterclockwise, and disconnect RCA cables.

6. Connect one pair of speaker cables to either high level input terminal on UUT. Cables should be connected to an integrated amplifier fed by the signal generator.

7. Turn on generator and adjust so that speaker level output is 1.0V, 50 Hz. Turn VOLUME control full clockwise.

8. Green LED should light, immediate bass response should be heard and felt from port tube opening.

Sweep Function

1. Follow steps 1 - 4 above, using a sweep generator as a signal source.

2. Sweep generator from 20Hz to 300Hz. Listen to the cabinet and drivers for any rattles, clicks, buzzes or any other noises. If any unusual noises are heard, remove driver and test.

Driver Function

1. Remove driver from cabinet; detach + and - wire clips.

2. Check DC resistance of driver; it should be 3.3 ohms.

3. Connect a pair of speaker cables to driver terminals.  Cables should be connected to an integrated amplifier fed by a signal generator. Turn on generator and adjust so that speaker level output is 5.0V.

4. Sweep generator from 20Hz to 1kHz. Listen to driver for any rubbing, buzzing, or other unusual noises.