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7. Air Leak Test

NOTE: Part A. of this test can be performed with

a fully assembled module.

A. Connect an oscillator to the module's left/right

(L/R) audio input terminals. Adjust the oscillator

to 40 Hz,1 Vrms. Listen for air leaks around the

transformer cup gasket. If there is

a"whooshing"noise,there is probably an air leak

around the gasket. Refer to the Disassembly/

Assembly Procedures section for instructions

on accessing this gasket. Re-position the

transformer cup gasket under the cup to make an

airtight seal.

NOTE: In order to perform the remaining

procedures,it is necessary to disassemble the

module to the woofer level. Leave all connections

intact to perform these tests. Remove the cover

using the procedures in the Disassembly/

Assembly Procedures section. Remove 6

screws which secure the heatsink to the module.

Remove 2 screws which secure the transformer

cup to the module. Slide out the transformer cup

and PCBs carefully. Lay the module on its side to

access the woofer more easily.

B. Using the same oscillator setting as part A.,

listen for air leaks around the woofer gasket. If

there is a "whooshing" noise around the

gasket,re-position the woofer gasket behind the

woofer to make an airtight seal.

8. Woofer Rub and Tick Test

A. Connect an oscillator to the module's L/R

audio input terminals. Adjust the oscillator to 10

Hz,1.5 Vrms. 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 woofer 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 woofer should be

replaced. If the noise stays the same,it is normal

suspension noise and the woofer is fine.

Suspension noises will not be heard with

program material.

9. Woofer Phase Test

A. Disconnect the woofer (connector J4) from the

Amplifier PCB. Set a DC power supply to 8

volts. Connect the positive supply lead to the

positive (+) woofer connection (red) and the

negative supply lead to the negative (-) woofer

connection (black). The woofer should move

outwards with the application of the supply

voltage.

10. Frequency Response of Bass Channel

NOTES: Pull the heatsink away from the

Amplifier PCB to expose the board's solder side.

It will be necessary to access the woofer output

connector (J4) to perform the remaining

procedures.

Bass amplifier output measurements are made

across J4 pins 1 and 2. The amplifier uses a

bridged output. Do not connect either output to

ground. Any test equipment that will be

connected to these points must be floated,or

isolated from ground.

A. Make up a temporary set of connections to the

woofer output connector J4.

B. Connect an oscillator to the module's L/R

audio input terminals. Adjust the oscillator to 100

Hz,200 mVrms.

C. Connect a piece of test equipment capable of

measuring decibels to the woofer output

connector J4. Make sure that the meter is not

grounded. Measure the decibels at this setting

and use as a reference for all other readings.

D. Adjust the oscillator frequency and measure

the relative response according to the chart

located at the end of this procedure (next page).