Bowers & Wilkins 704 S2 User manual

The contents of this document and associated files contain confidential information that is propriety to B&W
Group Ltd., and are intended solely for the purpose of servicing the product. The information is intended for use
by service technicians familiar with electronic products. No part of the contents should be supplied or published
elsewhere.
Page 1 © B&W Group Ltd 2017
Hub Service Technical Manual
704 Series 2
Gloss Black San White Rosenut

The contents of this document and associated files contain confidential information that is propriety to B&W
Group Ltd., and are intended solely for the purpose of servicing the product. The information is intended for use
by service technicians familiar with electronic products. No part of the contents should be supplied or published
elsewhere.
Page 2 © B&W Group Ltd 2017
Date Revision By Details
21/05/2018 1JP Creaon
Revision History
Front Cover Page 1
Revision History Page 2
Contents Page 2
Introducon Page 3
Technical Sheet Page 4
Exploded Diagram & Parts List Page 5 - 6
HF/ MF Crossover Diagram & Parts List Page 7
LF Crossover Diagram & Parts List Page 8
1. Tool Kit Page 9
2. Cosmec Inspecon Page 10
3. Plinth Removal Page 11
4. Tweeter Removal Page 12 - 14
5. Mid Removal Page 15 - 18
6. Drawbar Adjustment Page 18 - 19
7. Bass Removal Page 20 - 21
8. Terminal Tray/ Port Removal Page 22 - 23
9. HF/ MF & LF Crossovers Page 24 - 27
10. Funconal Test Page 28 - 29
11. Cleaning Page 30
12. Spare Parts Page 31
13. Product Test List Page 32
14. Test Result Sheet Page 33 - 34
Contents

The contents of this document and associated files contain confidential information that is propriety to B&W
Group Ltd., and are intended solely for the purpose of servicing the product. The information is intended for use
by service technicians familiar with electronic products. No part of the contents should be supplied or published
elsewhere.
Page 3 © B&W Group Ltd 2017
Introducon
Please read this manual carefully before commencing servicing!
Only qualied and authorised technicians should aempt to service this product.
Anstac Precauons (ESD)
Electronic devices and components are extremely sensive to electrostacs
(ESD). Always observe ESD precauons when handling electronic modules or
PCBs. Never exchange boards with a dierent revision number, unless
authorised by B&W Whenever you see this warning,
always take electrostac
precauons.
Chemicals and Solvents (COSHH)
Solder’s, uxes and cleaning agents are used widely in the servicing of electronic
products. Such substances are hazardous to health; therefore always take
precauons to protect yourself and others when using any hazardous substance.
Protecve clothing and equipment if provided should be worn. If in doubt refer
to the COSHH.
Be aware whenever
you see this warning.
Electricity
Electricity is the most common hazard that will be confronted when building
and tesng product. Always take precauons when working on live
equipment or with any test equipment that uses electricity. Note: Do not
wear an ESD wrist strap when working on live electricity. Be aware whenever
you see this warning.
Personal Protecon Equipment (PPE)
PPE is equipment that will protect the user against health or safety at work. It
can include items such as safety helmets and hard hats, gloves, eye protecon,
high visibility clothing, safety footwear and safety harnesses.
Be aware whenever
you see this warning.

The contents of this document and associated files contain confidential information that is propriety to B&W
Group Ltd., and are intended solely for the purpose of servicing the product. The information is intended for use
by service technicians familiar with electronic products. No part of the contents should be supplied or published
elsewhere.
Page 4 © B&W Group Ltd 2017
704 S2 Series Technical Sheet
Technical features Decoupled Carbon Dome tweeter
Connuum cone FST midrange
Decoupled midrange
Aerofoil prole bass cones
Flowport™
Descripon 3-way vented-box system
Drive units 1x ø25mm (1 in) Decoupled Carbon Dome high-
frequency
1x ø130mm (5 in) Connuum cone FST midrange
2x ø130mm (5 in) Aerofoil prole bass
Frequency range -6dB at 43Hz and 33kHz
Frequency response 48Hz - 28kHz ±3dB
Sensivity 88dB spl (2.83Vrms, 1m)
Harmonic distoron 2nd and 3rd harmonics (90dB, 1m)
<1% 100Hz - 22kHz
<0.5% 300Hz - 20kHz
Nominal impedance 8Ω (minimum 3.1Ω)
Recommended amplier power 30W - 150W into 8Ω on unclipped programme
Dimensions Height: 925mm (36.4 in) cabinet only
959mm (37.8 in) including plinth
Width: 165mm (6.5 in) cabinet only
252mm (9.9 in) including plinth
Depth: 255mm (10in) cabinet only
277mm (10.9 in) inc. grille and terminals
298mm (11.7 in) inc
Net weight 18.5kg (41 lb)
Finishes Cabinet: Rosenut
Gloss Black
San White
Grille: Black
Grey (San White only)

The contents of this document and associated files contain confidential information that is propriety to B&W
Group Ltd., and are intended solely for the purpose of servicing the product. The information is intended for use
by service technicians familiar with electronic products. No part of the contents should be supplied or published
elsewhere.
Page 5 © B&W Group Ltd 2017
Exploded Diagram & Parts List

The contents of this document and associated files contain confidential information that is propriety to B&W
Group Ltd., and are intended solely for the purpose of servicing the product. The information is intended for use
by service technicians familiar with electronic products. No part of the contents should be supplied or published
elsewhere.
Page 6 © B&W Group Ltd 2017
Parts List
ITEM PART NAME DESCRIPTION
PART #
BLACK
PART #
WHITE
QTY
1NXM10000056703000 Gasket 5” Chassis PM/CM/68x S2 GG12742 GG12742 2
2NXM10000067381000 Scr M4x12 Cap Hd CR3 Black HH35904 HH35904 8
3NXM10000099337000 Bass Unit 5” 704 S2 LF26824 LF26824 2
4NXM10000056095000 Port Tube Inc Flare 50x25mm Abs Black PP17601 PP17601 1
5NXM10000106827000 T/Ring Assy LF 700 S2 5” Dark RR35211 RR35289 2
6NXM10000104602000 Midrange Fixing Assy 702/704 S2 ZZ34142 ZZ34142 1
7NXM10000064490000 Tweeter Gasket GG14184 GG14184 1
8NXM10000108617000 X-Over LF 704 S2 XX16950 XX16950 1
9NXM10000105282000 Grille Mesh 700 S2 HF (I/B) Black GG16012 GG16012 1
10 NXM10000065708000 Term Tray/ Port 50mm Nickel 6 Mntg Studs ZT26670 ZT26670 1
11 NXM10000099341000 Mid 5”” Dark Trim 704 S2 LF27170 LF27189 1
12 NXM10000067048000 Grille CM8 S1/2, 704 S2 Black ZG02899 N/A 1
13 NXM10000108581000 Decoupler MF 5” - Front—700 S2 MM14613 MM14613 3
14 NXM1000010682000 Trim Assy HF 700 S2 (Bae) Dark RR35440 RR35432 1
15 NXM10000067015000 CM8 S2 / 704 S2 Plinth Assy Black ZZ28665 ZZ28673 1
16 NXM10000108616000 X-Over HF/ MF 704 S2 XX16969 XX16969 1
17 NXM10000098329000 Tweeter Bae Mounted 700 S2 HF01511 HF01511 1
18 NXM10000058250000 Gasket Term Tray 1mm Polyethylene S/A GG06491 GG06491 1
19 NXM10000070716000 MF Centraliser Nut HH36463 HH36463 1

The contents of this document and associated files contain confidential information that is propriety to B&W
Group Ltd., and are intended solely for the purpose of servicing the product. The information is intended for use
by service technicians familiar with electronic products. No part of the contents should be supplied or published
elsewhere.
Page 7 © B&W Group Ltd 2017
HF/ MF Crossover Diagram & Parts List
ITEM DRAWING NUMBER DESCRIPTION PART # QTY
ASSY NXD10000108616 X-Over CM8 HF/ MF S3 XX16969 1
PCB NXD10000110813 PCB 3 Way—HF/ MF S3 CC72133 1
HAR NXD10000065997 CM8 S2 HF/ MF Harness Assembly ZX10146 1
C1 Cap5.6 M-Cap 450VDC EVO Silver Gold Oil CC64653 1
C2 Cap 47uF PP 250V Carli CC58164 1
C3 Cap 10.0 M-Cap 450VDC EVO Silver Gold Oil CC64661 1
C4 Cap 0.01uF TDK 630V RAD EPCOS 10mm Pitch CC87165 1
C5 Cap 0.01uF TDK 630V RAD EPCOS 10mm Pitch CC87165 1
C6 Cap 0.01uF TDK 630V RAD EPCOS 10mm Pitch CC87165 1
L1 Ind 0.75mH 1.2Wire 24 ID 50OD 33L Pacic ZL11428 1
L2 Ind0.7mH 1.2mm AC Bobbin Pacic ZL11215 1
R1 Res 1R5 1% Powertron RR34304 1
1White Cable Ties 530mm x 9.0mm CC14540 1
2Label CM8S3 HF/ MF Crossover LL14222 3
3Spacer. SRS8-8-01 HH31619 1
4Heat Sink Ali “”Type B”” - 50.4mm Long HH40363 4
5Termal Pad Q Pad II—102 (Bergquist) HH31039 1
6Heat Sink Clip 2004 800 Series X-Overs PP19695 1
7Adhesive Hot Melt 988A 11mm OD AA14494

The contents of this document and associated files contain confidential information that is propriety to B&W
Group Ltd., and are intended solely for the purpose of servicing the product. The information is intended for use
by service technicians familiar with electronic products. No part of the contents should be supplied or published
elsewhere.
Page 8 © B&W Group Ltd 2017
LF Crossover Diagram & Parts List
ITEM DRAWING NUMBER DESCRIPTION PART # QTY
ASSY NXD10000108617 X-Over CM8 LF S3 XX16950 1
PCB NXD10000108566 PCB 3 Way—LF—CMS3 CC72125 1
HAR NXD10000066262 CM8 S2 LF Harness Assembly ZX10197 1
C1 Cap 120uF 100V 5% Elec B04 CC57642 1
C2 Cap 0.01uF TDK 630V RAD EPCOS 10mm Pitch CC87165 1
L1 Ind 2.52mH 1.2mm P2535+P4507 x 2 Cose Pacic ZL11231 1
L2 Ind 1.0mH 1.2mm P2535+P4507 x 2 Cose Pacic ZL11193 1
R2 Res 0R5 1% Powertron RR34282 1
1Cable Tie 300mm 4TR—1194#5 CC60001 4
2Labwl CM8S3 LF Crossover LL14214 1
3Spacer, SRS8-8-01 HH31619 4
4Heat Sink Ali “”Type B”” - 50.4mm Long HH40363 1
5Thermal Pad Q Pad II—102 (Bergquist) HH31039 1
6Heat Sink Clip 2004 800 Series X-Overs PP19695 1
7Adhesive Hot Melt 988A 11mm OD AA14494

The contents of this document and associated files contain confidential information that is propriety to B&W
Group Ltd., and are intended solely for the purpose of servicing the product. The information is intended for use
by service technicians familiar with electronic products. No part of the contents should be supplied or published
elsewhere.
Page 9 © B&W Group Ltd 2017
1. Tool Kit
The tools listed in the below table are required to carry out the servicing of the 704 Series 2
Speakers.
1. HF/ MF Tool Kit 2017
2. Phillips Screwdriver
3. Allen Key 3.0mm

The contents of this document and associated files contain confidential information that is propriety to B&W
Group Ltd., and are intended solely for the purpose of servicing the product. The information is intended for use
by service technicians familiar with electronic products. No part of the contents should be supplied or published
elsewhere.
Page 10 © B&W Group Ltd 2017
2. Cosmec Inspecon
A Cosmec Inspecon is done visually and should be done before any work commences.
This is to ensure that there is no external damage to the 704 Series 2 Speaker.
The Cabinet (Including Speaker Terminals & Flowport) (1), Tweeter (2), Mid Driver (3),
Bass Driver (4) should be checked for damage during the inspecon. (Damage should be
noted in report)
1
2
3
4
4

The contents of this document and associated files contain confidential information that is propriety to B&W
Group Ltd., and are intended solely for the purpose of servicing the product. The information is intended for use
by service technicians familiar with electronic products. No part of the contents should be supplied or published
elsewhere.
Page 11 © B&W Group Ltd 2017
3. Plinth Removal
Prior to servicing the 704 Series 2, it is recommended that the Plinth is removed.
To safely remove the Plinth without damaging the 704 Series 2 we recommend following the
below steps:
 Place the cloth bag over the top of the 704 Series 2 ensuring that the Tweeter and top
of the cabinet are covered. (The cloth bag is supplied with the original packaging)
 Aach the Poly Top to the top of the 704 Series 2.
 Carefully place the 704 Series 2 on its side. Ensure the poly remains in place.
 Carefully li the 704 Series 2 so that it is now upside-down on the poly.
 You can now access the 4 screws at the base of the Plinth to safely remove the it
without damaging the cabinet.
6. Reverse the process to safely turn over the 704 Series 2 and return it to its upward
posion.

The contents of this document and associated files contain confidential information that is propriety to B&W
Group Ltd., and are intended solely for the purpose of servicing the product. The information is intended for use
by service technicians familiar with electronic products. No part of the contents should be supplied or published
elsewhere.
Page 12 © B&W Group Ltd 2017
4. Tweeter Removal
Start by using Tool 1.5 - MM09989 HF Trim Removal Tool. Insert the Lip of the Trim Removal
Tool into the Tweeter Trim. Lever the Trim Removal Tool against the Grille unl Tweeter Trim
begins to li from the cabinet (1).
Note: Take care when pung pressure on the Grille so not to damage the Tweeter
The Outer-Rim can now be removed and placed to one side awaing reassembly. Take note
of correct orientaon of the Tweeter Trim (Small arrow and single plasc peg at the top). (2)
With the Tweeter Trim removed you are able
to unscrew the 4 x Screws holding the
Tweeter Assembly in place (3-6).
1
2
34
56

The contents of this document and associated files contain confidential information that is propriety to B&W
Group Ltd., and are intended solely for the purpose of servicing the product. The information is intended for use
by service technicians familiar with electronic products. No part of the contents should be supplied or published
elsewhere.
Page 13 © B&W Group Ltd 2017
Carefully ease the Tweeter forward from the cabinet and remove the Black (-) (1) and Red
(+) (2) Leads. Ensure that the Foam Gasket (3) remains in posion for reassembly. (Take
note of the red paint on the right (+) Tweeter connecon, this is to show the Red (+) cable
posion)
Note: If the Tweeter is stuck in posion and cannot be eased forward it may be necessary
to remove the Mid/Base Speaker. This will allow access to the rear of the Tweeter Assem-
bly so that you can gently push it forward unl free.
With the Tweeter Assembly removed, access
to the rear of the Tweeter can be gained. Start
by removing the 4 x Screws (4-7) around the
Plasc Retainer. The Plasc Retainer can then
be removed and placed to one side.
Note: Take care removing the Plasc Retainer
so as not to damage the Rubber Gasket.
1
2
3
45
6
7

The contents of this document and associated files contain confidential information that is propriety to B&W
Group Ltd., and are intended solely for the purpose of servicing the product. The information is intended for use
by service technicians familiar with electronic products. No part of the contents should be supplied or published
elsewhere.
Page 14 © B&W Group Ltd 2017
With the Plasc Retainer (1) removed you are able to use the magnec side of
Tool 1.5 – MM09989 HF Trim Removal Tool to gently li the Tweeter Grille (2) from the
Tweeter Assembly (3)
IMPORTANT: Ensure you do not touch the Tweeter when removing the Grille as this will
mark or damage the Tweeter. This cannot be reced without replacement.
Please work backwards through the Tweeter Disassembly process ensuring all the below
points:
• Gaskets are correctly posioned and not damaged
• All screws are ghtened
• Cables and tweeter are orientated correctly (Red Paint – Red Cable,)
• Tweeter Trim is correctly posioned with arrow and single plasc peg at the top
Reassembling the Tweeter
1
2
3

The contents of this document and associated files contain confidential information that is propriety to B&W
Group Ltd., and are intended solely for the purpose of servicing the product. The information is intended for use
by service technicians familiar with electronic products. No part of the contents should be supplied or published
elsewhere.
Page 15 © B&W Group Ltd 2017
5. Mid Removal
Start by gently easing out the Foam Dust Cap (1) at the centre of the Mid Unit. Minimal force
is required as the Dust Cap should simply slot in and out of place.
Once the Dust Cap is removed you will see the Drawbar Assembly (2). For adjustment of the
Drawbar please refer to 5. Drawbar Adjustment on Page 15.
To remove the Mid Unit you require Tool 1.3 – HH15121 MF Removal Tool. This can be found
as Tool 3 in the HF/ MF Toolkit 2017.
The MF Removal Tool has two funcons. The rst required funcon is to remove the nut
from the Drawbar Assembly.
Begin by aaching the two arms (3 & 4) two as shown in the below image (5).
12
34
5

The contents of this document and associated files contain confidential information that is propriety to B&W
Group Ltd., and are intended solely for the purpose of servicing the product. The information is intended for use
by service technicians familiar with electronic products. No part of the contents should be supplied or published
elsewhere.
Page 16 © B&W Group Ltd 2017
Once the MF Removal Tool has been correctly assembled you can use it to unscrew the nut
from the Drawbar (1).
Note: With the nut removed the Mid Unit is now sat freely on the Drawbar. Ensure that the
Mid Unit does not slide forward as this may damage the cabinet.
1
Now that the nut is removed the next
step is to adjust the MF Removal Tool to
allow for its second funcon.
Unscrew both arms and screw them into
the opposite end of the MF Removal
Tool (2).
2

The contents of this document and associated files contain confidential information that is propriety to B&W
Group Ltd., and are intended solely for the purpose of servicing the product. The information is intended for use
by service technicians familiar with electronic products. No part of the contents should be supplied or published
elsewhere.
Page 17 © B&W Group Ltd 2017
You can now screw the adjusted MF Removal Tool into the center of the M id Unit (1).
Once the tool has been ghtened in posion you will be able to ease the Mid Unit o the
drawbar and out of the cabinet (2).
1
2
Note: Take note of the cable posions
• Brown = Posive (+)
• Blue = Negave (-)
With the Mid Unit removed you can clearly
see the Drawbar (3) that the Mid Unit is
mounted on allowing it to oat in the cabi-
net.
3

The contents of this document and associated files contain confidential information that is propriety to B&W
Group Ltd., and are intended solely for the purpose of servicing the product. The information is intended for use
by service technicians familiar with electronic products. No part of the contents should be supplied or published
elsewhere.
Page 18 © B&W Group Ltd 2017
To perform the adjustment the Foam Dusk Cap must be removed. We also recommend that
the Drawbar is adjusted while the 704 Series 2 is standing up. This is to ensure the correct
posioning of the Mid Unit on the Drawbar.
The Mid Unit should be posioned centrally and ush with the cabinet edges.
To do this you require Tool 1.3 – HH15121 MF Removal Tool and Tool 1.1 – HH15148 Screw-
driver 4mm x 100mm.
Tool 1.3 – HH15121 MF Removal Tool is
used to ghten and loosen the nut
which holds the Mid Unit on the Draw-
bar.
Adjusng this ghtens the Mid Unit to
the Drawbar
Tool 1.1 – HH15148 Screwdriver 4mm x
100mm is used to turn the drawbar
which decreases and increases the ten-
sion on the spring at the back of the
Drawbar. Turning this moves the Mid
Unit in/ out of the cabinet.
Reassembling the Mid
Please work backwards through the Mid Removal process ensuring all the below points.
• Brown (+) and Blue (-) cables are ed securely and correctly
• Mid Unit is posioned on the Drawbar with the bar going through the hole in the back.
• Nut is ghtened on the Drawbar. Do not over ghten.
6. Drawbar Adjustment

The contents of this document and associated files contain confidential information that is propriety to B&W
Group Ltd., and are intended solely for the purpose of servicing the product. The information is intended for use
by service technicians familiar with electronic products. No part of the contents should be supplied or published
elsewhere.
Page 19 © B&W Group Ltd 2017
To Move the Mid Outwards
To bring the Mid Unit towards you will need to also loosen the nut which holds the Mid
Unit in posion on the Drawbar. To do this please follow the below steps:
• Firstly, loosen the nut by turning the MF Removal Tool (1) an-clockwise
• Secondly, simultaneously turn both tools (1 & 2) an-clockwise unl the Mid Unit sits
in the desired posion.
• Finish by turning the MF Removal Tool (1) clockwise to ghten the nut so that the
Mid Unit is secure on the Drawbar. Do this with the Screwdriver in place to stop the
Mid rotang. Ensure you do not over ghten.
To Move the Mid Inwards
To move the Mid Unit inwards please follow the below steps:
• Turn the Screwdriver (2) clockwise unl the Mid Unit sits in the desired posion.
• Turn the MF Removal Tool (1) clockwise to ghten the nut so that the Mid Unit is
secure on the Drawbar. Do this with the Screwdriver in place to stop the Mid ro-
tang. Ensure you do not over ghten.
1
2
To carry out the adjustments you should aach Tool 1.3 – HH15121 MF Removal Tool to the
nut (1) and then slide Tool 1.1 – HH15148 Screwdriver 4mm x 100mm into the end of the
MF Removal Tool. Posion the Screwdriver so that it nds the slot in the top of the Drawbar
(2).

The contents of this document and associated files contain confidential information that is propriety to B&W
Group Ltd., and are intended solely for the purpose of servicing the product. The information is intended for use
by service technicians familiar with electronic products. No part of the contents should be supplied or published
elsewhere.
Page 20 © B&W Group Ltd 2017
7. Bass Removal
Start by pung your ngers against the
Rubber inner and your thumb on the
edge of the Cabinet and gently ease the
Aluminium Trim (1) outwards.
Pull evenly around the Aluminium Trim
so as not to bend the Plasc Pegs. Con-
nue this unl the Trim comes away
from the Cabinet.
Note: When reassembling, look to
align the 4 x Plasc Pegs on the Alu-
minium Trim with the Plasc Sockets
on the cabinet. 1
2
Place the 704 Series 2 on its back and use Tool 1.3 – Allen Key 3.0mm to remove the 4 x Hex
Bolts (2-5).
This will allow you to safely remove the Bass Unit without damaging the Cabinet.
3
4
5