Bose | 301 Series III | User manual | Service Manual 301® SERIES IV DIRECT

301

®

SERIES IV DIRECT/REFLECTING

®

SPEAKER SYSTEM

®

© 1996 Bose Corporation

Service Manual

P/N 181850 REV 1

Table Of Contents

BOSE ® 301 ® SERIES IV TECHNICAL DESCRIPTION ............................................................................... 2

SPECIFICATIONS ......................................................................................................................................... 2

DISASSEMBLY/ASSEMBLY PROCEDURES .............................................................................................. 3

1. Grille Removal ........................................................................................................................................... 3

2. Woofer Removal/Replacement ................................................................................................................. 3

3. 3" Tweeter Removal/Replacement ............................................................................................................ 3

4. 2" Tweeter Removal/Replacement ...

....................................................................................................... 3

5. Remounting the Grille ............................................................................................................................... 4

TEST PROCEDURES .................................................................................................................................... 5

1. Woofer Rub and Tick Test ......................................................................................................................... 5

2. Woofer Sweep Test ................................................................................................................................... 5

3. Tweeter Sweep Test .................................................................................................................................. 5

4. Air Leak Test ...

............

.........

.................................................................................................................... 5

5. Woofer Phase Test .................................................................................................................................... 5

6. Tweeter Phase Test ................................................................................................................................... 6

7. Crossover Testing ..................................................................................................................................... 6

Figure 3: 301 Series IV Main Assembly Drawing ........................................................................................ 7

Figure 4: 301 Series IV Packaging Parts Drawing ...................................................................................... 8

TABLES

301 Series IV Main Assembly Parts List .................................................................................................... 9

301 Series IV Crossover Parts List .......................................................................................................... 10

301 Series IV Main Packaging Parts List ................................................................................................. 10

PROPRIETARY INFORMATION

THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION

OF BOSE CORPORATION WHICH IS BEING FURNISHED ONLY

FOR THE PURPOSE OF SERVICING THE IDENTIFIED BOSE

PRODUCT BY AN AUTHORIZED BOSE SERVICE CENTER OR

OWNER OF THE BOSE PRODUCT, AND SHALL NOT BE RE-

PRODUCED OR USED FOR ANY OTHER PURPOSE.

1

BOSE

®

301

®

SERIES IV TECHNICAL DESCRIPTION

The BOSE 301 Series IV speaker is a replacement for the 301 Series III and 4.2

® Series II speakers. It is a passive, two-piece (mirror image stereo pair) home loudspeaker in a bookshelf configuration. The 301 Series IV is designed for use with standard amplifiers, receivers and other related home audio components.

The 301 Series IV speaker utilizes separate inward and outward firing tweeters to achieve consistent stereo imaging over a broad listening area (Stereo Everywhere ® performance), while maintaining a spacious sound stage.

Asethetically, the 301 Series IV speaker features molded plastic right and left side caps mounted to a vinyl covered, particle board enclosure. This construction eliminates the use of edgebanding, and maintains differentation with competitors due to horizontal placement on the bookshelf.

The sum of all these unique features makes the 301 Series IV speaker capable of reproducing the wide dynamic range demanded by today’s advanced recordings without strain or loss of clarity.

SPECIFICATIONS

Speaker Compliment:

Nominal Impedance:

IEC Power Rating:

Cabinet:

Shipping Weight:

Speaker Dimensions:

One 8" (20 cm) woofer

One 3" (7.6 cm) tweeter

One 2" (5.08 cm) tweeter

8 Ohms

Min: 10 Watts per channel

Max: 75 Watts per channel

All Black, all Warm Gray or Rosewood finish w/Black End Caps

27.7 lbs. (12.6 kg) per pair

10.25"H x 16.38"W x 9.5"D

2

DISASSEMBLY/ASSEMBLY PROCEDURES

Note: Refer to Figure 3 for the following procedures.

tweeter from the molded bracket portion of the endcap.

1. Grille Removal: Both the front grille (1) and the side grille (3) are held in place by a snap-fit and are easily removed by hand. To remove,

CAREFULLY pull the grille away from the speaker.

2. Woofer Removal/Replacement:

3.4 Cut the wires connected to the tweeter as close to the tweeter terminals as possible.

3.5 Strip the wires and connect the replacement tweeter. Make sure the Yellow wire is connected to the positive (+) terminal and the Black wire is connected to the negative terminal (-).

2.1 Remove the front grille as indicated in Procedure 1.

3.6 Remount the tweeter using the #8-32 screw.

2.2 Remove the 4 screws (11) holding the woofer

(9) in place.

3.7 Remount the woofer using the four #8-11 screws.

2.3 Lift the woofer out and cut the wires connected to the woofer terminals as close to the terminals as possible.

4. 2" Tweeter Removal/Replacement: In order to remove the tweeter it will first be necessary to remove the woofer from the enclosure.

Note: The positive terminal of the tweeter is marked with a Red dot.

2.4 Strip the wires and connect to the replacement woofer. Make sure that the Red wire is connected to the positive (+) terminal, both Black wires are connected to the negative (-) terminal and both Yellow wires are connected to the woofer's "dummy" terminal, (no solder joint at this terminal). Dress or twist wires to prevent buzzing.

4.1 Remove the front grille only, as indicated in

Procedure 1.

4.2 Remove the 4 screws that secure the woofer to the enclosure and lift the woofer away from its opening.

2.5 Remount the woofer to the cabinet using the four screws.

4.3 Remove the #8-32 screw from the back of the gasket backed tweeter (12) and separate the tweeter from the molded bracket portion of the endcap.

3. 3" Tweeter Removal/Replacement: In order to remove the tweeter it will first be necessary to remove the woofer from the enclosure.

Note: The positive terminal of the tweeter is marked with a Red dot.

4.4 Cut the Yellow wire and the lamp lead connected to the tweeter as close to the tweeter terminals as possible.

3.1 Remove both the front and side grilles as indicated in Procedure 1.

4.5 Strip the Yellow wire and connect the replacement tweeter. Make sure the Yellow wire is connected to the negative (-) terminal and the lamp is connected to the positive terminal (+).

3.2 Remove the 4 screws that secure the woofer to the enclosure and lift the woofer away from its opening.

Note: To replace just the lamp or both the tweeter and lamp it will be necessary to remove the tweeter by following procedures outlined in section 4.

3.3 Remove the #8-32 screw (6) from the back of the gasket backed tweeter (4) and separate the

3

4.6 Remount the tweeter using the #8-32 screw.

4.7 Remount the woofer using the four #8-11 screws.

5. Remounting the Grilles: Both side and front grilles can only be mounted one way.

5.1 Side Grille: Align the feet with the fast-on grommets. Press in lightly until the grille feet are fully inserted into the grommets and the snap is engaged.

5.2 Front Grille: Align the feet with the four mounting holes on the end caps and press the grille in lightly until the snaps are engaged.

4

TEST PROCEDURES

Note: Before performing any tests, remove both grilles by following the grille removal instructions in the disassembly section of this manual.

Note: There should not be any buzzes or rattles from within the speaker cabinet. Redress any wire or component that buzzes.

1. Woofer Rub and Tick Test: Connect the output of a signal generator to the input of a power amplifier. Connect the output of the power amplifier to the input terminals of the speaker under test, (see Figure 1). Adjust the frequency of the generator to 45 Hz and the amplifier output to 8 Vrms. No extraneous noises such as rubbing, scraping or ticking should be heard.

3. Tweeter Sweep Test: Reduce the amplifier output to 3 Vrms and continue sweeping from 5 kHz to 15 kHz. Replace either of the tweeters in which buzzing or distortion occurs.

4. Air Leak Test: Using an 8 Vrms signal, set the generator frequency to 45 Hz. Listen for air leaks around the woofer, tweeters and cabinet seams (glue joints). Any air leaks will be heard as a sputtering or hissing sound. The repair of air leaks can be made by repositioning the transducer gaskets.

Note: To distinguish between normal suspension noise and rubs or ticks, slightly displace the cone of the woofer with your fingers. If the noise can be made to go away or get worse, it is a rub or 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.

5. Woofer Phase Test:

Note: In this test, supply voltage should only be momentarily applied to the speaker input terminals to avoid possible damage to the speaker.

2. Woofer Sweep Test: Sweep the signal generator from 10 Hz to 5 kHz using the 8 Vrms signal.

There should be no loud extraneous sounds. If there are any loud buzzes or distortion, replace the woofer.

Set a DC power supply to 8 volts. To ensure that the woofer is connected in phase, connect the positive lead of the supply to the positive (+) speaker input terminal and the negative lead to the negative (-) input terminal. The woofer should move outwards with the application of the supply voltage.

Test Connections, 301 ® Series IV Speaker

Audio Signal

Generator Power Amplifier

Input Output

-

+ -

+ +

Back of Speaker

Under Test

Black ( - )

5

RIGHT

Red ( + )

FIGURE 1

This ensures that the woofer and speaker input terminals are wired in phase, (see Schematic

Diagram, Figure 2).

6. Tweeter Phase Test: Remove 4 screws and lift the woofer carefully away from the speaker cabinet in order to access the terminal cup.

Check the wiring on the terminal cup and on both sets of tweeter terminals against the schematic in Figure 2. This ensures that both tweeters are wired in phase.

Note: Due to the inaccessibility of the tweeters, it may be necessary to remove the tweeters from their respective endcaps. Refer to the

Disassembly Procedures on replacing tweeters and for separating the tweeters from the endcaps.

7. Crossover Testing: The crossover is tested by measuring the voltage across a 10

Ω

, 5 watt resistor in series with the loudspeaker. See

Figure 2 and the following Table. If output voltage is not within the limits shown, check connections and component values for C1, C2, and RT1.

Crossover Measurements

Z ( + )

W

10

Y ( - )

Schematic Diagram

RT1

YEL

+

-

C1

RED

2" TWEETER

+

-

BLK

C2

8" WOOFER

6

YEL

BLK

+

-

3" TWEETER

FIGURE 2

10

A

C1

C2

RT1

6

11

B

12

4

5

3

6

7

8

9

See Detail A for Logo

Variations and Placement

Note: Exploded view of end caps is to show

relative location of crossover components as

well as the tweeters and is not intended to

represent a serviceable part.

1

2

2

Detail A

Logo Variations & Placement

( Left Speaker Shown )

FIGURE 3: 301 ® Series IV Main Assembly Drawing

7

7 1 2 3

4 5 6

8

9

8

10

FIGURE 4: 301 ® Series IV Packaging Parts Drawing

8

301

®

Series IV Main Assembly Parts List (Figure 3)

Item

Number

Description Part Number Q t y .

Per

Speaker

Reference

1

2

Grille Assembly, Front:

Brown/Grey or

Black

Nameplate, Logo:

Large or

Small

181851-01

181851-00

122812-0

185208-01

1

1

1

1

3 Grille Assembly, Side:

Dark Brown or

Black

181856-01

181856-00

1

1

4 Tweeter, 3" Gasket Backed 266161 1 11/4/2002

5 Grommet, Grille Socket 176068 2

6

7

Screw, Machine, 8-32 x .375, HexW, Hex 121441-06

Batting, Polyester, 12 x 2 116082

8 Gasket, Woofer, 8" 187395-208 1

9 Woofer Assembly, 8" 181870-0 01 1

2

1 See Note

10

11

Connector, Barrier, 2 Position

Screw, Tapp, 8-11 x .75, Pan

181865

172672-12

1

4

12 Tweeter, 2", Gasket Backed 181862-S P 1 10/1/2002

Note: This item is not normally stocked as a service part.

9

301

®

Series IV Crossover Parts List (Figure 3)

Symbol or Item

Number

C1

C2

RT1

A

B

Description

Capacitor, 4.5uF, 50V, 10%, Elect.

Capacitor, 22uF, 50V, 10%, Elect.

Lamp, Green dot

Connector, Terminal, Wirewrap

Tape, Foil

Part Number

131428

184956

141989

181864

103597

Q t y .

Per

S p e a k e r

Assy.

1

1

1

1

3"

Notes:

1. C2 is mounted to the surface of the woofer basket using foam tape P/N 118223.

2. This part is not normally stocked as a service part.

S e e

Note

1

2

2

301 Series IV Main Packaging Parts List (Figure 4)

Item

Number

7

8

5

6

9

10

3

4

1

2

Description

Owner's Manual

List, Warranty Service Stations

Card, Info, Warranty, Multi Language

Card, Info, Warranty, U.S.

Brochure, All Products

Bumper, Foot, Adhesive Backed, 8-ct

Polybag, 14.38 x 9.87 x 2 mil

Packing, Corner Post Set

Polybag, 13.5 x 35 x 9.5 x 2.5, 5 mil

Carton, RSC

Part Number Q t y .

Per

Carton

181869 1

122766

181460

1

1

181357

141478

173012-08

103351

1

1

1

1

181867

114522

181868-01

2

2

1

Reference

10

SPECIFICATIONS AND FEATURES SUBJECT TO CHANGE WITHOUT NOTICE

Bose Corporation

The Mountain

Framingham, Massachusetts USA 01701

P/N 181850 7/96 REV. 1

FOR TECHNICAL ASSISTANCE AND PARTS ORDERING, CALL 800-367-4008