Roland PX-7B - User Manual

SERVICE NOTES
Issued by RJA
Copyright © 2013 Roland Corporation
All rights reserved. No part of this publication may be reproduced in any form without the written permission
of Roland Corporation.
CC-KWS17058887E0
Oct. 2013 PX-7B, PX-7C
PX-7B
PX-7C
Table of Contents
Keyboard Parts List (PX-7B)............................................2
Keyboard Parts List (PX-7C)............................................3
Keyboard Assembly Procedure ......................................4
Circuit Board (Low, Mid).................................................9
Circuit Board (High) .......................................................12
Circuit Diagram (Low) ...................................................14
Circuit Diagram (Mid)....................................................16
Circuit Diagram (High) ..................................................18
This service note contains information about repair parts and the repair method of the keyboard section.
For other sections of each model, please refer to each service note.
Revise Information
Dec. 2, 2013 p. 6 Changed grease.
May. 24, 2016 p. 2 Added parts.
Jul. 29. 2016 p. 3 Added the PX-7C keyboard parts list.
Aug. 10, 2016 p. 3 Changed a part code.

Summary

Keyboard Parts List (PX-7 B)

Keyboard Parts List (PX-7 C)

Keyboard Assembly Procedure

Removing the Key

Procedure for safely removing a key from the keyboard mechanism.

Installing the Key

Steps for correctly installing a key back into the keyboard mechanism.

Installing the Circuit Board

Circuit Board Installation Steps

Detailed steps for mounting and securing the circuit board onto the sub-chassis.

Application of Grease

Greasing Points Identification

Identifies specific points on the keyboard mechanism requiring grease application.

Grease Amount Guidelines

Visual guide demonstrating the correct quantity of grease for key components.

Hammer Placement

Hammer Placement Details

Guidance on correctly positioning hammers based on shape, color, and frequency range.

Affixing the Cushion

Cushion Placement Instructions

Instructions for correctly affixing various types of cushions to the keyboard mechanism.

Circuit Board (Low, Mid) Diagram

Printed Wiring Board (LH Assembly) Diagram 1

Circuit Board (High) Diagram

Printed Wiring Board (LH Assembly) Diagram 2

Circuit Diagram (Low) - Part 1

Circuit Diagram (Low) - Part 2

Circuit Diagram (Mid)

Circuit Diagram (High Frequency IC)

Circuit Diagram (High) - Part 1

Circuit Diagram (High) - Part 2

Overview

1. Function Description
2. Important Technical Specifications
3. Usage Features
4. Maintenance Features

The provided document is a service note for the Roland PX-7B and PX-7C digital pianos, focusing specifically on the keyboard assembly, its components, and maintenance procedures.

Function Description:

The Roland PX-7B and PX-7C are digital pianos, and this service note details the repair and maintenance of their keyboard sections. The keyboard assembly is the primary interface for the user, translating physical key presses into digital signals for sound generation. It comprises various components including keys (N-Key for natural keys and S-Key for sharp keys), hammers, cushions, circuit boards, and a rubber switch matrix. The system is designed to simulate the feel and response of an acoustic piano, with different hammer weights and cushion types contributing to the touch sensitivity across the keyboard's range.

Important Technical Specifications:

The keyboard assembly for both PX-7B and PX-7C models utilizes a complex arrangement of parts to achieve its functionality.

• Key Types: N-KEY (natural keys) and S-KEY (sharp keys) are used, with specific part codes for different key positions (e.g., N-KEY C, D, E, F, G, A, B, and A/C DASH keys).
• Hammers: There are four types of hammers (HAMMER-1, -2, -3, -4) for both N-Keys and S-Keys. These hammers are differentiated by their metal and plastic portions, which vary according to the frequency range they cover (A0-F#2, G2-E4, F4-D6, D#6-C8). This variation in hammer design is crucial for simulating the graded hammer action of an acoustic piano, where lower notes have heavier hammers and higher notes have lighter ones.
• Cushions: Five types of cushions are used: KEY CUSHION A, KEY CUSHION B, KEY CUSHION E, HAMMER CUSHION A, and HAMMER CUSHION B. These cushions are essential for key return, noise reduction, and overall key feel.
• Circuit Boards: The keyboard section includes multiple circuit boards (Low, Mid, High) that house the rubber switches and other electronic components. These boards are responsible for detecting key presses and velocity.
• Rubber Switches: A 12P rubber switch (Part Code 5100047674) is a critical component for key detection. The circuit diagrams illustrate how these switches are arranged in a matrix to register key presses.
• Grease: Two types of grease are specified for lubrication: MORICOAT G-1039 (pink, #17041858) for key pivots, hammer pivots, and contact points between sharp keys and hammers (actuator area); and FLOIL G-336A (white, #17049543) for key guides and contact points between natural keys and hammers (actuator area). The correct application of these greases is vital for smooth key action and preventing wear.
• Screws: Various binding taptite screws (3x6, 3x8, 3x10) are used for securing components.
• Flat Cables: Flat cables (e.g., A-1.0-20X230-4/8-0.7X0.05 for PX-7B, SML2CD-20X222-BDX8(BL)-P1.0-S4 for PX-7C) connect the different circuit boards within the keyboard assembly.

Usage Features:

This document is a service manual, so it does not describe user-facing features. Instead, it focuses on the internal mechanics that contribute to the instrument's playability. The design of the keyboard, with its varied hammer weights and cushion types, aims to provide a realistic and expressive piano playing experience. The precise placement of components and application of lubricants are critical to maintaining the intended "key touch" and responsiveness that users expect from a Roland digital piano.

Maintenance Features:

The service note provides detailed instructions for maintaining and repairing the keyboard section:

• Key Removal and Installation: Specific procedures are outlined for removing keys using needle-nose pliers, emphasizing the order of removal (white keys before black keys) and the importance of avoiding grease contamination on the rubber switch. Installation requires aligning the key with the guide and pivot until an audible click is heard, with a reverse order of installation (black keys before white keys).
• Circuit Board Installation: Instructions detail peeling off adhesive tape, aligning the circuit board notch with the sub-chassis tab, and fastening with screws, first in round holes and then in slotted holes.
• Grease Application: This is a critical maintenance step. The document explicitly identifies "greasing points" (key pivot, hammer pivot, key guide, and actuator areas) and specifies the type and color of grease to be used for each point. Visual aids are provided to show the reasonable amount of grease to apply.
• Hammer Placement: A crucial section warns against incorrect hammer placement, which can impede key touch. It provides a chart and photos to verify the correct hammer type (1L, 2L, 3L, 4L) based on the frequency range and key color (white or black), as indicated by stamps on the hammer surface.
• Cushion Affixing: Instructions for positioning and affixing the five types of cushions are given, emphasizing proper alignment, ensuring no meandering, protrusion, or peeling, and trimming any protruding portions. It also advises pressing down Hammer Cushion B to prevent rubbing against the surface.
• Part Codes: Comprehensive parts lists are provided for both PX-7B and PX-7C models, including part codes, names, descriptions, and quantities, which are essential for ordering replacement parts.
• Circuit Diagrams: Detailed circuit diagrams for the Low, Mid, and High sections of the keyboard are included, aiding in troubleshooting and understanding the electronic connections.
• Revise Information: A "Revise Information" table tracks changes to the service note, such as updated grease types, added parts, and changed part codes, ensuring technicians have the most current information.

Roland PX-7B Specifications