Service Manual 301® SERIES IV DIRECT

®
301® SERIES IV DIRECT/REFLECTING® SPEAKER SYSTEM
Service Manual
©
1996 Bose Corporation
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 REPRODUCED 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:
One 8" (20 cm) woofer
One 3" (7.6 cm) tweeter
One 2" (5.08 cm) tweeter
Nominal Impedance:
8 Ohms
IEC Power Rating:
Min: 10 Watts per channel
Max: 75 Watts per channel
Cabinet:
All Black, all Warm Gray or Rosewood
finish w/Black End Caps
Shipping Weight:
27.7 lbs. (12.6 kg) per pair
Speaker Dimensions:
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 3.4 Cut the wires connected to the tweeter as close
side grille (3) are held in place by a snap-fit and
to the tweeter terminals as possible.
are easily removed by hand. To remove,
CAREFULLY pull the grille away from the
3.5 Strip the wires and connect the replacement
speaker.
tweeter. Make sure the Yellow wire is connected to the positive (+) terminal and the Black
2. Woofer Removal/Replacement:
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.
3.7 Remount the woofer using the four #8-11
screws.
2.2 Remove the 4 screws (11) holding the woofer
(9) in place.
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.
4.4 Cut the Yellow wire and the lamp lead connected to the tweeter as close to the tweeter
Note: The positive terminal of the tweeter is
terminals as possible.
marked with a Red dot.
4.5 Strip the Yellow wire and connect the replace3.1 Remove both the front and side grilles as
ment tweeter. Make sure the Yellow wire is
indicated in Procedure 1.
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
Note: To replace just the lamp or both the tweeter
opening.
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
5. Woofer Phase Test:
noise can be made to go away or get worse, it
is a rub or tick and the woofer should be reNote: In this test, supply voltage should only
placed. If the noise stays the same, it is normal
suspension noise and the woofer is fine. Susbe momentarily applied to the speaker input
pension noises will not be heard with program
terminals to avoid possible damage to the
speaker.
material.
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.
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.
Test Connections, 301® Series IV Speaker
Audio Signal
Generator
Power Amplifier
Input
Output
+
+ -
+
RIGHT
Back of Speaker
Under Test
Red ( + )
Black ( - )
FIGURE 1
5
This ensures that the woofer and speaker input
terminals are wired in phase, (see Schematic
Diagram, Figure 2).
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.
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
7. Crossover Testing: The crossover is tested by
both sets of tweeter terminals against the
measuring the voltage across a 10 Ω, 5 watt
schematic in Figure 2. This ensures that both
resistor in series with the loudspeaker. See
tweeters are wired in phase.
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
Schematic Diagram
RT1
+
YEL
2" TWEETER
-
C1
RED
Z(+)
+
W
-
Y(-)
10
BLK
8" WOOFER
C2
YEL
+
-
3" TWEETER
BLK
FIGURE 2
6
10
B
A
12
C1
C2
RT1
6
11
4
5
6
8
7
9
3
See Detail A for Logo
Variations and Placement
1
2
2
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.
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
1
Description
Part Number
Qty.
Reference
Per
Speaker
Grille Assembly, Front:
Brown/Grey or
Black
181851-01
181851-00
1
1
Nameplate, Logo:
Large or
Small
122812-0
185208-01
1
1
Grille Assembly, Side:
Dark Brown or
Black
181856-01
181856-00
1
1
4
Tweeter, 3" Gasket Backed
266161
1
5
Grommet, Grille Socket
176068
2
6
Screw, Machine, 8-32 x .375, HexW, Hex
121441-06
2
7
Batting, Polyester, 12 x 2
116082
1
8
Gasket, Woofer, 8"
187395-208
1
9
Woofer Assembly, 8"
181870-001
1
10
Connector, Barrier, 2 Position
181865
1
11
Screw, Tapp, 8-11 x .75, Pan
172672-12
4
12
Tweeter, 2", Gasket Backed
181862-SP
1
2
3
Note: This item is not normally stocked as a service part.
9
11/4/2002
See Note
10/1/2002
301® Series IV Crossover Parts List (Figure 3)
Symbol
or Item
Number
Description
Part Number
Qty.
Per
See
Note
Speaker
Assy.
1
C1
Capacitor, 4.5uF, 50V, 10%, Elect.
131428
C2
Capacitor, 22uF, 50V, 10%, Elect.
184956
1
RT1
Lamp, Green dot
141989
1
A
Connector, Terminal, Wirewrap
181864
1
2
B
Tape, Foil
103597
3"
2
1
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.
301 Series IV Main Packaging Parts List (Figure 4)
Item
Number
Description
Part Number
1
Owner's Manual
181869
Qty.
Per
Carton
1
2
List, Warranty Service Stations
122766
1
3
Card, Info, Warranty, Multi Language
181460
1
4
Card, Info, Warranty, U.S.
181357
1
5
Brochure, All Products
141478
1
6
Bumper, Foot, Adhesive Backed, 8-ct
173012-08
1
7
Polybag, 14.38 x 9.87 x 2 mil
103351
1
8
Packing, Corner Post Set
181867
2
9
Polybag, 13.5 x 35 x 9.5 x 2.5, 5 mil
114522
2
10
Carton, RSC
181868-01
1
10
Reference
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