Yamaha Silent Piano GB1KS Manual

MAINTENANCE HANDBOOK
GB1KS
MHB29
May, 2011

- 1 -
Foreword
This handbook covers maintenance for GB1KS, the Silent Grand Piano released in September
2009.
For additional information, see GPS-GB1 Service manual PP008615
Table of Contents
1. Unit structure and Names ---------------------------------------- 2
2. Adjustment / Checking points ------------------------------------ 4
3. Piano regulation caution -------------------------------------------5
4. Check regulation and Adjustment Silent mechanism -------6
5. Silent let-off Adjustment --------------------------------------------9
6. Sensor Unit Adjustment -------------------------------------------12
7. Maintenance and Test Modes -----------------------------------13
8. Unit Connection Diagram -----------------------------------------16
9. Parts List ---------------------------------------------------------------17

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Fig.1
Fig.2
Fig.3
1. Unit Structure and Names
① Switch Box
② Shift Pedal
③ Sostenuto Pedal / Bass-damper Pedal
-Europe: Sostenuto Pedal
-US / CANADA: Bass-damper Pedal
④ Damper Pedal
GB1KS switches Silent / Acoustic mode
with the operation lever and detects key
and pedal movement.
⑤ Key Sensor Unit
-Key sensor unit adjustment ⇒P.12
-Key sensor measurement P.13
⑥ Regulating Rod
-Check/ adjustment ⇒P.8
-Silent let-off adjustment ⇒P.9 - 11
⑦ Hammer Shank Stopper
-Check / adjustment ⇒P.6, 7
Switch Box
-Front side
Power Switch
Reverb Adjustment
Knob
-Right side diagram
Volume Knob
Headphone Jacks
Test Switch -Back side
Pedal Connector
Key Connector
[DC IN 12V] Connector

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Fig.4
⑧ Silent Lever
-Stroke adjustment of Silent lever
⇒P.6
⑨ Shift Pedal Sensor
Shift sensor ON/OFF
-How to check / adjust the sensor detection
position
⇒P.14
⑩ Damper Pedal Sensor
Variable Resister (VR) Sensor
ON / Half / OFF
-Damper pedal sensor measurement
⇒P.14
-How to check the sensor detection position
⇒P.14
-Damper pedal sensor position adjustment
⇒P.15
-Bottom face diagram
Switch
B
ox

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2. Adjustment/ Confirmation Items
Adjustment item Description Ref. page
Piano regulation caution ・Disengage Silent mechanism
・Disconnect sensor cable
⇒P.5
Silent mechanism ・Check / adjustment ⇒P.6
・Check / adjustment of hammer shank stopper ⇒P.6
・Hammer shank stopper rotation amount adjustment
(Vertical to hammer shanks)
⇒P.6
・Hammer shank stopping position adjustment
5 - 6mm (Normally only checking)
Replace the cushioning only when greatly differing
from standard.
(List of cushioning parts ⇒P.7 )
⇒P.7
・Check / adjustment of the regulating rod ⇒P.8
Silent let-off adjustment ・Level adjustment of the regulating rod
Escapes at the shank stopping position :1 to 2mm
before shank stopping position.
⇒P.9
Sensor unit adjustment ・Key sensor unit adjustment
Gap between the bottom surface of black keys and
the upper surface of key sensor unit when pressing
the black keys to the lowest position : 3.8 to 4.0mm
⇒P.12
・Adjustment of pedal sensor unit ⇒P.12 - 15
Maintenance mode ・Program to adjust the detection position of the key
sensor and damper pedal sensor by measurement.
・Executes measurement after the key sensor
adjustment.
⇒P.13
Test mode ・Program to check the detection position of the key
sensor and damper pedal sensor.
・Measurement result and adjustment status can be
confirmed.
⇒P.14

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3. Piano Regulation
-Piano regulation may be done independently from the Silencing mechanism.
When pulling an action for tuning and voiving, operate the Silent lever to release the Silent
mechanism (Fig.5) and remove the key sensor connector in front of the action. (Fig.6)
Fig.5
Fig.6
-Hammer let-off : approx. 2mm (normally same distance as GP)
-Hammer drop : 2-point matching (Fig.7: simultaneous contact of ① and ②)
-Other regulation : same as GP
Fig.7

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4. Check/ Adjustment of Silent mechanism
-Adjustment of action in the Silent mode is done with the Silent mechanism engaged.
-Switching of silent/ normal play is done with the Silent lever attached to the treble bottom of
keybed.
-The Silent lever can have the units interlock as listed below.
①The link in the back beam rotates ②The lever link rotates (white plastic)
③Shank stopper drive lever rotates ④Shank stopper rotates
⑤Regulating rod drive lever rotates ⑥Regulating rod rotates
-In the Silent mode, the hammer shank stopper and regulating rod are set simultaneously.
Therefore, these two parts shall need check and adjustment.
-In the Silent mode, the sostenuto pedal is ineffective.
[Hammer shank stopper check/ adjustment]
① Pull the Silent lever to activate the Silent mechanism.
② Adjust and set the hammer shank stopper cushion to contact the hammer shank
vertically. Visual confirmation is possible (Fig.8).
③ Set the hammer shank stopping position to 5 – 6mm from the strings (Fig.11).
④ Disengage the Silent lever and make sure that the hammer shanks do not contact
the hammer shank stopper when depressing keys.
◆Hammer shank stopper rotation amount adjustment
Stopper cushion position Vertical to the hammer shank
Adjustment spots Adjust cable length behind Silent lever (Fig.9). If adjusting
cable length is not enough, use the stroke adjustment screw
in the back of Silent lever (Fig.10).
Fig.8
Fig.9 Fig.10
Unscrew (lock after adjustment) Stroke Adjustment Screw

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◆Hammer shank stopping position adjustment
String stroke distance 5 - 6mm
Adjustment spot Replacement of the hammer shank stopper cushioning
(Normally visual confirmation only is OK.)
Fig.11
Shank stopper cushioning
Thickness (t) Component No. Remarks
5.5mm T6210100 Used in product
5.0mm T6210110 Same as above
4.5mm T6210120 Same as above
4.0mm T6210130 Same as above
3.5mm T6210140 Same as above
3.0mm T6210150 For adjustment
2.5mm T6210160 Same as above
Cushion length are all 378mm.
Cut as follows.
(Bass: 365mm, Middle: 375mm, Treble: 232mm)
Shank stopping position: 5 – 6mm from the string
Thickness (t) Cushioning

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[Regulating rod check / adjustment]
① Pull the Silent lever to activate the Silent mechanism.
② Check and adjust the contact angle of regulating rod.
③ Disengage Silent mechanism and make sure that the regulating rod does not
contact the jack.
◆Adjustment of contact angle to regulating rod
Angle position Regulating rod (b) and small jack’s knob (a) respectively contact in the
center position (Fig.12).
Adjustment
spot
Regulating rod drive lever adjustment screw installed in the back of the
action treble side (Fig.13: Rotation end position changes.)
Fig.12 Fig.13
・To rotate regulating rod more : Adjust screw clockwise
・To rotate regulating rod less : Adjust screw counterclockwise

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5. Silent let-off (=Hammer let-off in the Silent mode)
-Adjust the level of the regulating rod to the position so that jack [A] and [a] as a structure
respectively contact [B] and [b] almost simultaneously when the Silent mechanism is engaged
(Fig.14).
-The result of this adjustment will set the Silent let-off distance from the shank stopper +1 to 2mm
(Fig.15 : 6 to 8mm from the string).
Fig.14 Fig.15
◆Silent let-off adjustment
Silent let-off Escapes at the shank stopping position +1 to 2mm
(6 to 8mm from the string)
(At this time, jack [A] and [a] contact [B] and [b] almost
simultaneously.)
Adjustment spot Regulating rod adjustment screw (Fig.16)
Adjustment hint For 1 screw rotation, Silent let-off changes 3mm.
Adjustment
method
⇒P.10, 11
In Silent mode let-off, jack escapement (drop) cannot be seen. To
confirm Silent let-off, increase drop to 8 to 9mm.
-Adjust Silent mode let-off
To narrow Silent mode let-off : Rotate screw clockwise
To increase Silent mode let-off : Rotate screw counterclockwise
Fig.16
Silent let-off : shank stopping position +1 to 2mm
Shank stopping position : 6 to 8mm from the string