Bose Lifestyle PS48 Servicehandleiding - Pagina 37

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3.2 Measure the gain from the input to the A-

D converter to the speaker output listed in

the table below.

Channel

Left

Center

Right

Left Surround

Right Surround

Bass

4. Speaker Output Noise

4.1 Short the right and left inputs to the A-D

converter.

4.2 Measure the output at the left, right,

center, left surround, right surround, and

bass channel output. It should be < 500

uVrms.

5. Cube Channel Large Signal Distortion

5.1 Apply a 1.0 kHz signal to the A-D con-

verter input at a level to obtain 11 Vrms

measured at the channel's resistive output

load.

Note: When measuring the left or right

channel output, apply the signal to one

channel only. When measuring the center

channel, apply the signal to the left and right

channel. When measuring the surround

channels, apply the balanced output signal to

the left and right channel with one channel

180

out of phase with the other.

5.2 Issue the TAP command: VO CB 0

(set volume output to 0dB, full output)

5.3 Measure the distortion at the left, right,

center, left surround, right surround output. It

should be <0.1% THD+N.

6. Cube Channel DC Offset

6.1 With no signal applied, measure the DC

offset at the left, right, center, left surround,

right surround, and bass channel output. It

should be <70 mVdc.

Test Procedures

Gain

8dB ± 2.0dB

16dB ± 2.0dB

8dB ± 2.0dB

16dB ± 2.0dB

22dB ± 2.0dB

PS18/28/48 Service Manual

7. Bass Channel Large Signal Distortion

7.1 Apply a 100 Hz signal to the A-D converter

input at a level to obtain 11 Vrms measured at

the bass channel resistive output load.

7.2 Measure the distortion at the bass channel

output. It should be <.2% THD+N

8. Bass Channel DC Offset

8.1 With no signal applied, measure the DC

offset at the bass channel output. It should be

<25 mVdc.

9. Place the Unit in Normal Operation Mode

9.1 Before returning the bass module to the

customer, place the unit in normal operation

mode. Place all four DIP switches into the

down position (toward RCA plugs).

10. Cube Speaker Phase Test

Note: The DC voltage should only be momen-

tarily applied to the cube speaker input to

avoid damaging the speakers.

10. 1 Observing polarity, momentarily apply 8 Vdc

to the input of the cube speaker.

10.2 The speakers should move outward with

the application of the dc voltage. Check the

cube wiring if it moves inward.

11. Cube Speaker Sweep Test

11.1 Apply an 11 Vrms, 20 Hz signal to the

input of the cube. Change the applied signal to

8 Vrms, 150 Hz. Sweep the oscillator from 150

Hz to 2 kHz.

11.2 Listen for rubs, ticks, air leaks, buzzes or

other extraneous noises.

Note: Defects such as rubs, ticks and air leaks

will typically be most audible during the 20 Hz

test. Defects such as buzzes will typically be

heard during the 150 Hz to 2 kHz sweep.

Note: The cube cubes are not repairable. The

Jewel Cube

speakers are repairable.