Bose Lifestyle PS28 Manuale di servizio - Pagina 36

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Test setup procedures

Place the bass module into TAP mode using the

procedures on page 26.

Note: Place all four DIP switches into the down

position before returning the unit to the cus-

tomer.

Test cable part number 264564, Figure 16, is

needed to test the bass module.

Connect the D-sub, 9 pin connector on the test

cable to the COM port on your computer.

Connect the RJ-45, 8 pin connector to the bass

module.

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 con-

nector to the A-D converter S/PDIF output.

1. Sweep Test

1.1 Issue the following TAP commands:

SO ALL D

(select all digital source inputs)

SP 5

(5 speaker mode)

VO CB 0

(set volume to full output, 0dB)

MU AMP OFF (unmute the amp)

1.2 Apply a 200 mVrms, 25 Hz signal to the

left and right input of the analog to digital (A-

D) converter. Listen for any extraneous noises

such as rubbing, scraping, or ticking.

Note: No extraneous noises such as rubbing,

scraping or ticking should be heard. To distin-

guish 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.

1.3 Sweep the bass module from 40 Hz to 300 Hz.

Listen carefully for any buzzes, rattles

or extraneous noises coming from the bass

module.

Note: Redress any wire or component that

buzzes.

Test Procedures

2 Bass Module Air Leak Test

2.1 Apply a 200 mVrms, 40 Hz signal to the

input of the A-D converter.

2.2 Check for air leaks from the cabinet.

Listen near the areas where the plastic seals

to the wood.

Remove the amplifier module from the bass

module assembly. Refer to the disassembly/

assembly procedures located in this manual.

Connect an 8 Ohm, 50W resistive load to the

left, center, right, left surround, and right

surround speaker outputs. Connect a 1.6

Ohm, 150W resistive load to the woofer

output, J4.

Note: Do not tie the five RCA speaker output

grounds together.

Turn the amplifier off and then place it into

TAP mode using the procedures on page 26.

Issue the TAP command: VO CB -20

(set volume output to -20dB)

Note: Because the DSP has just booted (or

rebooted) prior to being put into TAP mode

and issuing this command, the amplifier

module is now in a known state.

3. Input to Output Gain

3.1 Apply a 500 mVrms signal, at a frequency

and phase listed in the following table, to the

left and right input of the A-D converter.

Note: For a 180

positive output of a balanced output oscillator

to the negative input of the A-D converter and

the negative to the positive.

Channel

PS18/28/48 Service Manual

Test setup procedures

phase output, apply the

Frequency

Input

1 kHz

500 mVrms

1 kHz

500 mVrms

1 kHz

500 mVrms

1 kHz

500 mVrms

1 kHz

500 mVrms

50 Hz

500 mVrms

Phase

Right

Left

180