Bose 251 Manuel utilisateur
1
251 Environmental Speaker 256033
CAUTION:The Bose®251™ Environmental Speaker contains
no user serviceable parts. To prevent warranty infractions,
refer servicing to warranty service centers or factory service.
PROPRIETARY INFORMATION
THIS DOCUMENT CONTAINS PROPRIETARY INFORMA-
TION OF BOSE CORPORATION WHICH IS BEING FUR-
NISHED 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.
WARRANTY INFORMATION
The Bose 251 Environmental Speaker is covered by a five year transferable limited warranty.
Contents
Product Description..........................................................................................................................2
Disassembly/Assembly Procedures ...............................................................................................2
Specifications....................................................................................................................................2
Disassembly/Assembly Procedures ...............................................................................................3
Figure 1. Wiring Diagram ....................................................................................................................3
Test Procedures ................................................................................................................................4
Figure 2. Schematic Diagram ..............................................................................................................4
Part List..............................................................................................................................................5
Figure 3. Exploded View ......................................................................................................................5
Packaging Part List ...........................................................................................................................6
Figure 4. Packaging View ....................................................................................................................6
2
251 Environmental Speaker 256033
SPECIFICATIONS
PRODUCT DESCRIPTION
The Bose®251™ Environmental Speaker is a premium environmental loudspeaker. Each loud-
speaker contains one 5.25” environmentally resistant woofer in a two-chamber configuration, two
2.5” environmentally resistant Twiddlers™ vertically stacked and angled for maximum horizontal
dispersion and a crossover including system protection. The system is packaged with mounting
brackets.
DISASSEMBLY/ASSEMBLY PROCEDURES
1. Grille and Baffle Removal
1.1 Grasp the edge of the grill (5) and pull it
off.
1.2 Remove the six screws (13) that secure
the baffle to the cabinet and then pull off the
baffle.
2. Grille and Baffle Replacement
2.1 To prevent air leaks, apply a new baffle
woofer mount gasket (10). To prevent wire
buzzes, insert the wires into the cabinet’s wire
channel. Line up the baffle so that the baffle’s
woofer mount fits into the groove in the
cabinet. Replace the six screws (13) that
secure the baffle to the cabinet.
2.2 Align the grille (5) with the cabinet so that
the logo (6) is over the Twiddlers (2). Press
the grille into place.
3.TwiddlerRemoval.
3.1 Perform procedure 1.1.
3.2 Remove the four screws (12) that secure
the Twiddler (2) to the cabinet.
3.3 Lift the Twiddler out and cut the wires as
close as possible to the wire terminal.
Note: Make a note of the wiring configuration.
4.Twiddler Replacement
4.1 Referring to the note taken in 3.3, attach
the wires to the Twiddler (2).
(Refer to Figure 3)
Transducers: One 5.25" environmental woofer per enclosure
Two 2.5" environmental resistant Twiddlers per enclosure
Impedance: 6 Ohms nominal (4.8 Ohms minimum) 20-20 kHz
Power Handling: 100W (24.5 Vrms) continuous per IEC 268-5
Recommended amp/receiver power 10-200W per channel.
Crossover Assembly: Crossover frequency: 250 Hz, 10% at 6 dB/octave
System Protection: System protection: PTC device.
Sensitivity: >82 dB SPL (1W, 1M) 400 Hz octave band limited pink noise
Flux Leakage: NA, not shielded; not for use near a video monitor
External Dimensions: 13.5" x 5.75" x 8.34" (34.3 x 14.6 x 21.2) cm
Weight: 7.75 lb. (3.5 kg)
3
251 Environmental Speaker 256033
DISASSEMBLY/ASSEMBLY PROCEDURES
9.2 Remove the four screws (12) that secure
the Twiddler panel (15) to the baffle. Pry off
the panel.
9.3 Cut the wires as close as possible to the
terminals of the capacitor (4).
10. Crossover Capacitor Replacement
10.1 Connect the leads of the capacitor (4) to
the wires and solder the connections. The
capacitor is wired in series with the woofer’s
(1) negative terminal and the Twiddler’s (2)
positive terminal. Refer to Figure 1.
10.2 To prevent air leaks, replace the Twiddler
panel (15) and gasket (9). Line up the
Twiddler panel (15) with the cabinet and
replace the four screws (12) that secure it to
the baffle.
(Refer to Figure 4)
4.2 Line up the Twiddler™ in the cabinet and
replace the four screws (12) that secure the
Twiddler in place.
5.Woofer Removal
5.1 Perform procedure 1.
5.2 Cut the wires as close as possible to the
woofer’s (1) wire terminal.
5.3 Remove the four screws (12) that secure
the woofer to the baffle. Lift the woofer out.
6.Woofer Replacement
6.1 To prevent air leaks, apply a new gasket
(11) to the woofer. Line up the woofer (1) in
the baffle so that the wire terminal is facing
toward the Twiddlers (2). Replace the four
screws (12) that secure the woofer to the
baffle.
6.2 Attach the green and black wires to the
negative terminal and the red and yellow
wires to the positive terminal of the woofer.
6.3 Place the foam tape gasket (10) around
the edge of the baffle’s woofer mount where it
contacts the cabinet.
7. Protection Circuit Removal
7.1 Perform procedure 1.
7.2 Cut the wires as close as possible to the
leads of the polyswitch (3).
8. Protection Circuit Replacement
8.1 Connect the leads of the polyswitch (3) to
the wires and solder the connections. The
polyswitch is wired in series with the
speaker’s positive terminal and the woofer’s
(1) positive terminal. Refer to Figure 2.
9. Crossover Capacitor Removal
9.1 Perform procedure 1.
Figure 1.Wiring Diagram
Wiring Diagram Table
From To Wire
Twid 1 (-) Twid 2 (+) Gray
Twid 1 (+) Woofer (-) Black
Twid 2 (-) Woofer (+) Red
Woofer (+) Terminal 1 (+) Yellow
Woofer (-) Terminal 2 (-) Green
4
251 Environmental Speaker 256033
++-
+
-
+
-
-
PTC
Woofer Twiddlers
33uF, BP
C1
Red
Black
Gray
Green
Yellow
2
1
TEST PROCEDURES
1. Woofer Rub and Tick Test
1.1 Apply a 6 Vrms, 10 Hz signal to the
speaker input terminal. No extraneous noises
such as rubbing, scraping or ticking should be
heard.
Note: To distinguish between normal suspen-
sion 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
okay. Suspension noise will not be heard with
program material.
2. Air leak Test
2.1 Apply an 8 Vrms, 65 Hz signal to the
speaker input terminal.
2.2 Listen for air leaks around the cabinet
seams, Twiddler™ panel, and the woofer and
Twiddler gaskets. Reposition or replace any
gasket that is found to leak. Repairs made to
the cabinet seam should not be visible from
the exterior of the speaker.
Note: A whooshing noise from the ports at
approximately 65 Hz and 185 Hz is accept-
able (port tuned frequencies).
3. Twiddler Phase Test
3.1 Check the wiring of the Twiddler against
Figures 1 and 2.
4. Sweep Test
4.1 Apply an 8 Vrms, 10 Hz signal to the
speaker input terminal.
4.2 Sweep the signal generator from 10 Hz to
5 kHz and then back to 10 Hz.
4.3 Apply a 3 Vrms, 5 kHz signal to the
speaker input terminal.
4.4 Sweep the signal generator from 5 kHz to
15 kHz and then back to 5 kHz.
4.5 Listen for buzzes, rattles or other noises.
Redress any wire that buzzes; replace the
woofer or Twiddler if they are found to be
defective.
5. Woofer Phase Test
5.1 Observing polarity, momentarily apply 8
VDC to the speaker input terminal.
Note: To avoid damaging the speaker, only
momentarily apply the DC voltage.
5.2 The woofer should move outward with the
application of the DC voltage.
Figure 2. Schematic Diagram
5
251 Environmental Speaker 256033
PART LIST
Figure 3. Exploded View
Item
Number
Description Part Number Qty
1 WOOFER, 5.25", ENVIRONMENTAL 289780-001 1
2 TWIDDLERTM, 60MM, ENVIRONMENTAL289783-001 2
3 POLYSWITCH, 60V, 160 190348-160 1
4 33uF, 50V, BI-POLAR, ELECTROLYTIC, AX 254351 1
5 GRILLE, METAL, BLACK
GRILLE, METAL, WHITE
250804-11
250804-12
1
6 LOGO, BLACK CABINET
LOGO, WHITE CABINET
250806-01
250806-02
1
7 CONNECTOR, ENVIRONMENTAL, BLACK 250815-01 1
8 CONNECTOR, ENVIRONMENTAL, RED 250815-02 1
9 TWIDDLER PANEL FOAM GASKET 250807 1
10 BAFFLE WOOFER MOUNT FOAM GASKET 250808 1
11 GASKET, 134MM, RD, ADHESIVE BACKED 290315-001 1
12 SCREW, TAPP, 8-11 X .5, PAN, ASY, SQ 296495-008 16
13 SCREW, TAPP, 8-11 X 1.0 PAN, ASY, SQ 296495-016 6
14 NUT, INSERT 250818 2
15 PANEL, SEALING, TWIDDLER 250820 1
16 GASKET, .725 ROUND 293936-001 1
17 TAPE, FILTER PORT 255910 1
17
6
251 Environmental Speaker 256033
PACKAGING PART LIST
Figure 4. Packaging View
Item
Number
Description Part Number Qty
1 CARTON, RSC, 15.63X11.63 X 16.06 294092 1
2 PACKING, END CAP, TOP 250809 1
3 PACKING END, CAP 250810 1
4 BAG, POLY, HDPE, 18 X 26, 1 MIL 255354-001 2
5 CREASE SHEET 15.50 X 33.25 250839 1
6BRACKET, ALUMINUM, BLACK
BRACKET, ALUMINUM, WHITE
250819-11
250819-12
2
7 KNOB, THREADED STUD, 1/4-20, BLACK
KNOB, THREADED STUD, 1/4-20, WHITE
250822-01
250822-02
1 pkg. of 4
8 HARDWARE KIT
CONSISTS OF:
SCREW,
DELETED
ANCHOR, WALL
293240-001
-
-
-
-
1 pkg.
8
-
-
8
9 FOOT, CLEAR, 250 DIAX. 085, SIX 250821-06 1 pkg. of 6
10 OWNER'S MANUAL 250811 1
11 INFO, WARRANTY, U.S. 181357 1
12 INFO, WARRANTY, MULTIPLE LANGUAGE 181460 1
13 DELETED
14 COMMITMENT LETTER 251001 1
15 BAG, POLY, 14.38 x 9.87 x 2mil 103351 1
Service Manual
©2004Bose Corporation
Bose®251™ Environmental Speaker
PartNumber 256033 REV.01
Specifications and Features Subject to Change Without Notice
Bose Corporation
The Mountain
Framingham Massachusetts USA 01701
P/N 256033 REV.013/2004
ECN 33972 - REV 00 TO REV 01
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