Yamaha F-20B, Bass Amplifier service manual Important Notice, Warning Chemical Content Notice

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F-20B

F-20B

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:

IMPORTANT:

Failure to follow appropriate service and safety procedures when servicing this product may result in per- sonal injury, destruction of expensive components and failure of the product to per form as specified. For these reasons, we advise all Yamaha product owners that all service required should be performed by an authorized Yamaha Retailer or the appointed service representative.

This presentation or sale of this manual to any individual or firm does not constitute authorization, certifica- tion, recognition of any applicable technical capabilities, or establish a principal-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, therefor, inevitable and changes in specification are subject to change without notice or obligation to retrofit. Should any discrepancy appear to exist, please contact the distributor's Service Division.

WARNING:

IMPORTANT:

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).

Turn the unit OFF during disassembly and parts replacement. Recheck all work before you apply power to the unit.

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 WHAT SO EVER!

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.

IMPORTANT NOTICE FOR THE UNITED KINGDOM

Connecting the Plug and Cord

WARNING: THIS APPARATUS MUST BE EARTHED

IMPORTANT: The wires in this main lead are coloured in accor- dance with the following code:

GREEN-AND-YELLOW: EARTH

BLUE: NEUTRAL

BROWN: LIVE

As the colours of the wires in the main lead of this apparatus may not correspond with the coloured markings identifying the terminals in your plug, proceed as follows:

The GREEN-and-YELLOW wire must be connected to the terminal in the plug that is marked with the letter E or the safety earth symbol (or coloured GREEN or GREEN-and-YELLOW).

The BLUE wire must be connected to the terminal that is marked with the letter N (or coloured BLACK).

The BROWN wire must be connected to the terminal that is marked with the letter L (or coloured RED).

This applies only to products distributed by Yamaha Kemble Music (U. K.) Ltd.

IMPORTANT NOTICE WARNING

Components having special characteristics are marked WARNING: CHEMICAL CONTENT NOTICE! and must be replaced with parts having specification equal to those

originally installed.

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Contents CONTENTS BASS AMPLIFIERIMPORTANT NOTICE F-20BWARNING CHEMICAL CONTENT NOTICE IMPORTANT NOTICE FOR THE UNITED KINGDOMF-20B SPECIFICATIONSPANEL LAYOUT POWER AMP BLOCK DIAGRAMCIRCUIT BOARD LAYOUT POWER TRANSFORMER2.Speaker Time required about 2 min DISASSEMBLY PROCEDURE1.Pre-MainUnit Time required about 2 min F-20BTime required about 3 min 5.Power Transformer Time required about 4 minF-20B 4.MAIN 2/2 Circuit Board CIRCUIT BOARDS F-20B3.Inspection procedure IC BLOCK DIAGRAM2.Power supply INSPECTIONSBASS AMPLIFIER CONTENSPARTS LIST F-20BF-20B OVERALL ASSEMBLY10 Overall Cabinet Assembly 20 Pre-MainUnitREMARKS F-20BDESCRIPTION New partsPRE-MAINUNIT F-20B V 6 9 5 4 8 0 0 ChassisELECTRICAL PARTS F-20BF-20B HF456330F-20B OVERALL CIRCUIT DIAGRAMABCDEFG P.1 5 F-20B