Bose 111 Manuale di servizio - Pagina 2

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Test Procedures

NOTES: In each test procedure, it is necessary to remove the grille to access the driver.

Refer to the Grille Removal procedure.

Polarities are not marked on the input terminals of the 151™ speaker. The red terminal is

the positive (+) terminal and the black terminal is the negative (-) terminal. See Figure 1.

1. Rub and Tick Test

A. Connect a sine wave oscillator to a power amplifier. Adjust the frequency of the oscillator

to 10 Hz and the amplifier output to 6 Vrms. Connect the amplifier output to the input

terminals of the 151 speaker (see Figure 1). No extraneous noises such as rubbing,

scraping or ticking should be heard.

NOTE: To distinguish between normal suspension noise and rubs or ticks, displace the

cone on the driver slightly with your fingers. If the noise can be made to go away or get

worse, it is a rub or a tick and the driver should be replaced. If the noise stays the same, it

is normal suspension noise and the driver is fine. Suspension noises will not be heard with

program material.

2. Sweep Test

A. Sweep the oscillator from 10 Hz to 3 kHz using the 6 Vrms signal. There should not be

any loud extraneous sounds. (Note: A "whooshing" noise from the port at approximately 80

Hz is acceptable). If there are any loud buzzes or distortion, replace the driver. (See

Disassembly/Assembly Procedures for instructions on replacing the driver).

NOTE: There should not be any buzzes or rattles from within the speaker cabinet. Redress

any wire or component that buzzes.

B. Reduce the amplifier output to 3 Vrms and continue sweeping from 3 kHz to 15 kHz. If

there is any buzzing or distorting,replace the driver (see Disassembly/Assembly

Procedures for instructions on replacing the driver).