Yamaha YST-MS50 User manual

100675
POWERED MULTIMEDIA SPEAKERS
YST-MS50/YST-MS55D
TO SERVICE PERSONNEL ........................................... 1
FRONT AND REAR PANELS..................................... 1~2
SPECIFICATIONS....................................................... 3~4
INTERNAL VIEW ............................................................ 4
DISASSEMBLY PROCEDURES .................................... 5
USB PORT OPERATION CHECK............................ 6~17
■CONTENTS
BLOCK DIAGRAM .................................................. 18~19
PRINTED CIRCUIT BOARD ...................................20~22
IC DATA ........................................................................ 23
SCHEMATIC DIAGRAM ......................................... 24~25
PARTS LIST ............................................................ 26~37
SERVICE MANUAL
IMPORTANT NOTICE
This manual has been provided for the use of authorized YAMAHA Retailers and their service personnel.
It has been assumed that basic service procedures inherent to the industry, and more specifically YAMAHA
Products, are already known and understood by the users, and have therefore not been restated.
WARNING: Failure to follow appropriate service and safety procedures when servicing this product
may result in personal injury, destruction of expensive components, and failure of the
product to perform as specified. For these reasons, we advise all YAMAHA product
owners that any service required should be performed by an authorized YAMAHA
Retailer or the appointed service representative.
IMPORTANT:The presentation or sale of this manual to any individual of firm does not constitute
authorization, certification or recognition of any applicable technical capabilities,
or establish a principle-agent relationship of any form.
The data provided is believed to be accurate and applicable to the unit(s) indicated on the cover. The research,
engineering, and service departments of YAMAHA are continually striving to improve YAMAHA products.
Modifications are, therefore, inevitable and specifications are subject to change without notice or obligation
to retrofit. Should any discrepancy appear to exist, please contact the distributor's Service Division.
WARNING: Static discharges can destroy expensive components. Discharge any static electricity
your body may have accumulated by grounding yourself to the ground buss in the unit
(heavy gauge black wires connect to this buss).
IMPORTANT:Turn the unit OFF during disassembly and part replacement. Recheck all work before
you apply power to the unit.

1
YST-MS50/YST-MS55D YST-MS50 YST-MS55D
■TO SERVICE PERSONNEL
1. Critical Components information.
Components having special characteristics are marked and
must be replaced with parts having specifications equal to
those originally installed.
2. Leakage Current Measurement (For 120V Model only).
When service has been completed, it is imperative that you
verify that all exposed conductive surfaces are properly insu-
lated from supply circuits.
●Meter impedance should be equivalent to 1500 ohm shunted by
0.15µF.
●Leakage current must not exceed 0.5mA.
●Be sure to test for leakage with the AC plug in both polarities.
WARNING: CHEMICAL CONTENT NOTICE!
The solder used in the production of this product contains LEAD. In addition, other electrical/electronic and/or plastic (where
applicable) components may also contain traces of chemicals found by the California Health and Welfare Agency (and possibly
other entities) to cause cancer and/or birth defects or other reproductive harm.
DO NOT PLACE SOLDER, ELECTRICAL/ELECTRONIC OR PLASTIC COMPONENTS IN YOUR MOUTH FOR ANY REASON
WHATSOEVER!
Avoid prolonged, unprotected contact between solder and your skin! When soldering, do not inhale solder fumes or expose eyes
to solder/flux vapor!
If you come in contact with solder or components located inside the enclosure of this product, wash your hands before handling
food.
WALL
OUTLET EQUIPMENT UNDER TEST
AC LEAKAGE
TESTER OR
EQUIVALENT
INSULATING
TABLE
■FRONT AND REAR PANELS
"CAUTION"
"F1: FOR CONTINUED PROTECTION AGAINST RISK OF FIRE,REPLACE ONLY WITH SAME TYPE 1.25A, 250V FUSE."
CAUTION
F1: REPLACE WITH SAME TYPE 1.25A, 250V FUSE.
ATTENTION
F1: UTILISER UN FUSIBLE DE RECHANGE DE MEME TYPE DE 1.25A, 250V FUSE.
A V
ˆ
•Satellite Speakers Front Panel •Satellite Speakers Rear Panel
YST-MS55D
Lch Rch Lch Rch

2
YST-MS50/YST-MS55D
YST-MS50 YST-MS55D
•Subwoofer Front Panel
•Subwoofer Rear Panel
YST-MS55D
YST-MS55D
YST-MS55D
YST-MS55D
R model only
U and C models
U and C models only
R modelA modelB and G models

3
YST-MS50/YST-MS55D YST-MS50 YST-MS55D
Operating Section
Satellite (Auto Power)Switch
Master Volume control
Subwoofer Volume control
Dimensions (W x H x D)
Satellite 97x159x178mm
(3-13/16"x6-1/4"x7-9/16")
Subwoofer 350x210x321mm
(13-25/32"x8-1/4"x12/5/8")
Weight
Satellite 0.7kg (1Ibls. 9 oz.)x2
Subwoofer 8kg (17Ibls. 10oz.)
Finish
YST-MS50
YST-MS50W Computer white color
YST-MS50B Black color
YST-MS55D
YST-MS55DW Computer white color
YST-MS55DB Black color
Accessories
YST-MS50
3.5mm stereo mini plug cable with black color(1.8m) x1
RCA pin plug cable (1.8m) x1
8 pin plug cable (1.8m) x1
8 pcs of nonskid pads x1set
YST-MS55D
3.5mm stereo mini plug cable with black color(1.8m) x1
RCA pin plug color (1.8m) x1
USB cable (2m) x1
8 pcs of nonskid pads x1set
CD-ROM x1
USB Operating Requirements YST-MS55D
:Windows 98-installed PC equipped with USB port.
:CD-ROM drive for device driver installation.
:Intel Pentium processor at least 200 MHz or equivalent.
:At least 10 MB of available hard disk capacity.
* Specifications subject to change without votice.
U ....... U. S. A. model A .......Australian model
C ....... Canadian model B .......British model
R ....... General model G .......European model
Type Active Servo Technology (Advanced Y. S. T)
Output Power
Satellite 20W+20W (1kHz, 4 ohms at T.H.D.=10%)
Subwoofer 40W (100Hz, 5 ohms at T.H.D.=10%)
Input Sencitivity 200mV (1kHz, 4 ohms at 20W)
Input Impedance 25 kohms
Frequency Responce 32 Hz to 20 kHz
Crossover Frequency
Satellite Tweeter 12 kHz
Subwoofer fc=200Hz
Headphone Output Level
0.38V/30 ohms (at 200 mV Rated Input)
Speaker Unit
Satellite
Tweeter : 19mm (3/4") balanced dome (JA0262),
Magnetic shielding Type
Midrange : 8cm(3") cone (JA0865),
Magnetic Shielding Type
Subwoofer : 16cm(6-1/2") cone (JA1673),
Magnetic Shielding Type
Input Sction
YST-MS50
Satellite 3.5mm stereo minijack for audio-signal x2
YST-MS55D
Satellite 3.5mm stareo mini jack for audio-signal x2
(USB in use x1)
Subwoofer USB digital x1
Output Sction
YST-MS50
Subwoofer RCA pin jack connected to L ch speaker
8 pin jack connected to R ch speaker
YST-MS55D
Subwoofer RCA pin jack connected to L ch speaker
8 pin jack connected to R ch speaker
3.5mm stereo mini jack for audio-signal x1
(USB in use)
Power Consumption 65W
Power Supply
U, C models AC120V/60Hz
R models AC110/120/220/240V/50/60Hz
A models AC240V/50Hz
B, G models AC230V/50Hz
"Windows 98", are trademarks of Micro Soft Corporation.

4
YST-MS50/YST-MS55D
YST-MS50 YST-MS55D
•DIMENSIONS
▼Satellite Speaker ▼Subwoofer
97 (3-13/16")
178 (7-9/16")
166(6-17/32")
159 (6-1/4")
210 (8-1/4") 321 (12-5/8")
350 (13-25/32")
■INTERNAL VIEW
•Satellite Speakers
Notes: The Satellite Speakers are available by the speaker unit (Lch or Rch).
Individual parts of the Satellite Speakers are not available. (See page 31 and 33 of the PARTS LIST for YST-MS50,
page 34 and 36 of the PARTS LIST for YST-MS55D.)
2
13
▼L ch ▼R ch
•Satellite Speaker (L ch)
1P. C. B. MAIN (8)
•Satellite Speaker (R ch)
2P. C. B. MAIN (4)
3P. C. B. MAIN (5)
•Subwoofer
4
8 9 0 A B
5 6 6 7
YST-MS50 YST-MS55D
•Subwoofer
4P. C. B. MAIN (6)
5P. C. B. MAIN (1)
6P. C. B. MAIN (3)
7P. C. B. MAIN (9)
(YST-MS55D only)
8SPEAKER UNIT
(Subwoofer)
9POWER TRANSFORMER
0P. C. B. MAIN (7)
AVOLTAGE SELECTOR (R only)
BP. C. B. MAIN (2)
Units : mm (inch)

5
YST-MS50/YST-MS55D YST-MS50 YST-MS55D
■DISASSENBLY PROCEDURES
(Remove parts in disassenbly order as numbered.)
•Disassemble of the Subwoofer
1. Removal of the Rear Panel Ass'y.
a. Remove 8 screws ( 1) in Fig. 1, and remove the rear
panel ass'y.
b. Disconnect one connector in Fig. 1.
c. Disconnect the Speaker cord in Fig. 1.
2. Removal of the Front Panel Ass'y
The front panel assy is fixed to the cabinet with dowels at 6
locations.
* As a screwdriver (for slotted head screw) is used for
removal, use special care not to cause damage to the
Cabinet.
a. Using the screwdriver insert in the gaps between the front
panel ass'y and cabinet, push up the front panel ass'y.
b. Remove the front panel ass'y while taking it out.
(Front panel ass'y can not to remove completely.)
3. Removal of the Speaker
a. Set up the front panel ass'y in the direction of the arrow,
in Fig. 2.
b. Remove 4 screws ( 2) in Fig. 2, and remove the
speaker.
Fig. 2
Fig. 1
Dowels Front Panel Ass'y
Cabinet
Connector
Gaps
Speaker Cord
Rear Panel Ass'y
Speaker
Front Panel Ass'y
1
2

YST-MS55D
■USB PORT OPERATION CHECK
The YST-MS55D have a USB port. This USB port operation is checked be necessary whether or not normal state.
1. BEFORE CHECKING THE USB PORT OPERATION
(1) Measuring Instruments
• Personal Computer (Windows 98)
• CD-ROM (Accessories)
• USB Cable (Accessories)
(2) USB Operating requirements
• Windows 98 installed Personal Computer equipped with USB port.
• CD-ROM drive for device driver installation.
• Intel Pentium processor at least 200MHz or equivqlent.
• At least 10MB of abailable hard disk capacity.
(3) Installing the YST-MS55D speaker device drivers
Please follow these steps to install the Yamaha YST-MS55D speaker device drivers in your Windows 98 system
using the included CD-ROM, and verify that Windows 98 recognizes the installed device drivers and that CD audio,
sound generated while using software, and system sounds from the personal computer will be output via the USB port.
1) Start up Windows 98 on your computer. Insert the included YST-MS55D device driver CD-ROM into the CD-
ROM drive
2) Connect the YST-MS55D speakers using the specified cables and plug them in to the AC outlet. At this time,
do not connect the subwoofer to the personal computer yet.
3) Make sure that the POWER switch on the rear panel of the subwoofer is turned on.
4) Connect the subwoofer to the USB port on the personal computer using the USB cable.
Notes: Before starting, check the above-mentioned “(2) USB Operating requirements” section to see if your PC
supports YST-MS55D. Also, make sure that no other CD-ROM is loaded in the CD-ROM drive and that you quit all
application programs.
Have your Windows 98 CD-ROM ready when you install the Yamaha YST-MS55D speaker device drivers. You may
need it in some cases.
The installation procedure may differ from the following instructions depending on the system environment. Follow the
instructions that appear in the dialog box.
6
YST-MS50/YST-MS55D

Message “Windows has found a new hardware and is locating the software for it.” appears, then:
The following “Add New Hardware Wizard” appears to install the USB Composite Device. (See Fig. 1)
1. Click [Next].
The system displays the following panel: (See Fig. 2)
The system displays the following panel: (See Fig. 3)
2. Click [Next] again to display the following
panel.
3. Check “CD-ROM drive” and de-select other
options, then click [Next] to proceed to the fol-
lowing panel:
Fig. 1
Fig. 2
Fig. 3
7
YST-MS50/YST-MS55D YST-MS55D

4. Make sure that “The updated driver (Recom-
mended)” lists “YAMAHA YST-MS55D USB
Composite Device,” then click [Next].
The system displays the following panel: (See Fig. 5)
The system displays the following panel: (See Fig. 4)
Note: Depending on your system, a path other than “D:\USB.INF” may appear.
5. Click [Next].
The system starts installing the YAMAHA YST-
MS55D USB Composite Device. Please wait
awhile.
The system displays the following panel: (See Fig. 6)
6. Click “Finish” to complete the installation of the
USB Composite Device.
Fig. 4
Fig. 5
Fig. 6
8
YST-MS50/YST-MS55D
YST-MS55D

The system displays a panel to begin installing a Human Interface Device. (See Fig. 7)
The system displays the following panel: (See Fig. 8)
7. Follow the screen instructions. Make sure that
“The updated driver (Recommended)” panel
lists “Human Interface Devices,” and click the
[Next] button repeatedly as in steps 2–5 until the
following panel appears:
8. Click “Finish” to complete the installation of the
Human Interface Device.
The system displays a panel to begin installing a USB Audio Device. (See Fig. 9)
9. Follow the same screen instructions as steps 2–5.
Make sure that “The updated driver (Recom-
mended)” panel lists “YAMAHA YST-MS55D
USB Audio” in step 4, and click the [Next] but-
ton repeatedly until the following panel
appears:
Fig. 7
Fig. 8
Fig. 9
9
YST-MS50/YST-MS55D YST-MS55D

CONFIRM 1 " YAMAHA YST-MS55D USB Audio "
Open the window by the order of [My Computer], [Control Panel],
[System], and click the [Device Manager] or [System Properties].
↓
Click the [View devices by type ].
↓
Confirm the "YAMAHA YST-MS55D USB Audio". (See Fig. 11)
Confirmed.
Fig. 11
↓
To next confirmation.
(4) Confirming the OS (Operating System)
Confirm that the installed the YST-MS55D speaker device driver.
There are 3 items in the YST-MS55D speaker device drivers.
Befor confirming,
1) Make sure that the POWER switch on the rear panel of the subwoofer is turned on.
2) Connect the subwoofer to the USB port on the personal computer using the USB cable.
There are 4 items in the confirmation as shown below.
The system displays the following panel: (See Fig. 10)
10.Click “Finish” to complete the installation of the
USB Audio Device.
Fig. 10
10
YST-MS50/YST-MS55D
YST-MS55D

CONFIRM 2 " Human Interface Devices "
Confirm the "Human Interface Devices". (See Fig. 12)
Confirmed.
Fig. 12
↓
To next confirmation.
11
YST-MS50/YST-MS55D YST-MS55D
CONFIRM 3 " YAMAHA YST-MS55D USB Composite Device "
Confirm the "YAMAHA YST-MS55D USB Composite Device". (See Fig. 13)
Confirmed
Fig. 13
↓
To next confirmation.

CONFIRM 4 " YAMAHA YST-MS55D USB Audio (1) "
Click the [Audio] of [Multimedia Properties].
↓
Confirm the [Playback ].
↓
Confirm the "YAMAHA YST-MS55D USB Audio (1) ". (See Fig. 14)
Confirmed.
Fig. 14
↓
Completed the confirmation of OS.
12
YST-MS50/YST-MS55D
YST-MS55D
CAUTION: If not installed the YST-MS55D speaker device drivers, repeat install from the CD-ROM.
(See page 6~10)

2. STARTING THE USB PORT OPERATION CHECK
The USB port operation check is using the USB Compliance check Test Tool Version 2.6. Install the this Test Tool.
Running the Test Tool.
↓
[PLUG IN DEVICE (S) TO TEST!] display.
Fig. 15
↓
Connect the USB cable to the USB port of the personal computer.
↓
Pulg in the USB cable from Personal to [USB INPUT] on the rear panel
of the Subwoofer. (See Fig. 16)
Plug in the
USB Cable from the
Personal Computer.
Fig. 16
↓
Start the USB port operation check.
13
YST-MS50/YST-MS55D YST-MS55D
Rear panel of the Subwoofer

3. DETAIL OF USB PORT OPERATION CHECK
There are 5 items in the USB port operation check as shown below.
CHECK 1 " 00Vid (0X0499) Pid (0X3001) "
[USB Compliance Tool, Version 2.6] display.
↓
Confirm the " 99 Vid (0X0499) Pid (0X3001)". (See Fig. 17)
↓
Confirmation of USB EEPROM (IC201) opration is completed.
↓
Click the [Full Test] (See Fig. 17) for next check.
Confirmed.
Click.
Fig. 17
14
YST-MS50/YST-MS55D
YST-MS55D

CHECK 2 All is checked ("✔").
[USB Chapter 9 Test] display.
↓
Confirm that all is checked ("✔"). (See Fig. 18)
↓
Click the [Start Automated Testing ] (See Fig. 18) for next check.
Fig. 18
All is checked ("✔").
Click.
15
YST-MS50/YST-MS55D YST-MS55D

CHECK 3 " Error Count : 0 "
[Full Test Results] display.
↓
Confirm the " Error Count : 0 ". (See Fig. 19)
↓
Operation of between USB IC and USB port is normal state.
↓
Enter automated to next check.
Fig. 19
Confirmed.
16
YST-MS50/YST-MS55D
YST-MS55D

CHECK 4 " OK "
[USB Compliance Tool] display.
↓
Confirm the " OK ". (See Fig. 20)
↓
Enter automated to next check.
Fig. 20
CHECK 5 " OK "
[DEVICE IS HID] display.
↓
Confirm the " OK ". (See Fig. 21)
↓
Completed the USB port operation check.
Fig. 21
Confirmed.
Confirmed.
17
YST-MS50/YST-MS55D YST-MS55D

YST-MS50/YST-MS55D
YST-MS50 YST-MS55D
18 19
■BLOCK DIAGRAM
Q2
Q3
Q201
JK202 L202
WP SDA
SCL VOUTL
VOUTR
XTAL1
XTAL2
SDA
D–
D+
SCL
75
624 21
V
SS
14
15
7
66
7
31
30
V
DD
+B
2
3
2
3
Q8
SW1
POWER
SW2
220V–240V
F1
F2
D2 IC2
GND
IN
+
–
OUT
IC5
GND
IN OUT
~
R model only
110V–120V
VOLTAGE
SELECTOR
POWER
TRANSFORMER
Regulator Regulator
(AUTO POWER)
Q1
3
5
VOLUME
VR1
VR2
IR
JK4
INPUT 1
INPUT 2
JK3
OUTPUT
TO RIGHT
SPEAKER
Rch SATELLITE SPEAKER
Lch SATELLITE SPEAKER
IL
31G
4
76
JK2
8
25
+12
+12
+12
PWS
TO
SUBWo.
TO LEFT
SPEAKER
USB IN USE ONLY
YST-MS55D
TO RIGHT
SPEAKER
OL
1
7
IC3
(NJM4556AL)
OR RSP–
RSP+
TWEETER
MIDRENGE
+
+
JK1
JK201
(HEADPHONE)
–
–
TWEETER
MIDRENGE
+
+
–
–
SUBWOOFER
SP+
SP–
E
–12
31G
4768
25
+12
E
OL
PWS
OR
RSP–
RSP+
JK5 –12
–12
6
4
–12
–12
+12
+12
1
2
H. P. F
12dB/oct
H. P. F
12dB/oct
–12
+12
–6dB/oct
–12
+12
–12dB/oct
EQ Amp
IC1,2
(UPC4570HA)
Mute
Power Amp.
IC6
(STK408-040E)
IC1
IC2 IC2
IC1 72
+12
84 IC7
A. N. I.C
IC8
IC7,8
(UPC4570HA)
–12
+12 –12
48
20
1
18
+12
27
–12
7
+12
+3.3V
8
–12
USB
INPUT
XL201
48MHz
EEPROM
IC202
(MC24C02-BN6)
USB D/A Converter
IC201
(UDA1321PS)
417
SWI
SRI
SLI
PWS1
RSP+
LSP+
PJ1
TO
SUB Wo.
PJ2
16
12
14
9
85
3
2
+B
–B
–B
+B
BASS
Rectifier
Q6 Q7
Q5Q4
~

1
2
3
4
5
6
YST-MS50/YST-MS55D
ABCDEFGH
YST-MS50 YST-MS55D
20
■PRINTED CIRCUIT BOARD (Foil side)
21
LSP+
E
LSP+
E
E
+B
W201
E
+B
SWI SRI SLI RSP+ PWS1 E E –12 +12
E
VOUT
VIN
VIN
VOUT
E
+ –
SUBWOOFER
POWER
TRANSFORMER
VOLTAGE
SELECTOR
POWER
TO RIGHT
SPEAKER
OUTPUT
USB
INPUT
TO LEFT SPEAKER TO RIGHT
SPEAKER
BASS
USB IN USE ONLY
110V-120V220V-240V
OFFON
SWI
SRI
SLI
RSP+
PWS1
E
E
–12
+12
RE BL WH
RE
RE
WH
WH
REWHGR
GR RE BE WH BR
WHBE
BRBE
RE
WH
BE
BL
WH
P. C. B. MAIN (9)
P. C. B. MAIN (3)
P. C. B. MAIN (6)
•
Subwoofer
P. C. B. MAIN (1)
P. C. B. MAIN (2)
P. C. B. MAIN (7)
YST-MS55D
R model only
J,U,C,A,B,G
only
R only
1
G
825
4673
91
91
201
OUT COM IN
IN COM OUT
UPC4570HA
UPC4570HA
STK408-040E
NJM79M12FA NJM78M12FA
58
41
1
32
16
17
12 43
UDA1321PS
M24C02-BN6
91
UPC4570HA
19
UPC4570HA
●Semiconductor Location
Ref. No.
D2
D3
D4
D5
D6
D7
D8
D201
D202
IC1
IC2
IC4
IC5
IC6
IC7
IC8
IC201
IC202
Q3
Q4
Q5
Q6
Q7
Q8
Q201
Location
H4
B2
E3
E3
D4
D4
D4
B5
E5
B3
D3
D5
D5
E4
D4
D3
B5
B5
B2
E3
E3
E3
E3
E3
B5