Yamaha F-20 Service Manual Download

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F-20

<P.1>

OVERALL CIRCUIT DIAGRAM

Note: See parts list for details of circuit board component parts.

TRANS

FORMER

MAIN

1/2

MAIN

2/2

VOLUME

GAIN

MASTER

CH SELECT A/B

POWER ON/OFF

INPUT

MIDDLE

BASS

TREBLE

AUX IN

PHONES

Ω

SPEAKER

OP AMP

HIFI AMP

KEC-54230

J, U, C

S, BS

250V 500mA 250V T160mA L

D2SBA20 (VP344100)
DIODE STACK 1.5A 200V

DB1

WARNING

Components having special characteristics are maked and
must be replaced with parts having specification equal to those originally installed.

Summary of Contents for F-20

Page 1: ...1 GA CONTENTS SPECIFICATIONS 3 PANEL LAYOUT 3 CIRCUIT BOARD LAYOUT 4 BLOCK DIAGRAM 4 DISASSEMBLY PROCEDURE 5 CIRCUIT BOARDS 7 IC BLOCK DIAGRAM 8 INSPECTIONS 8 PARTS LIST OVERALL CIRCUIT DIAGRAM GUITAR AMPLIFIER This document is printed on chlorine free ECF paper with soy ink ...

Page 2: ...g 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 an...

Page 3: ...V 50Hz Dimensions W x H x D 357 x 330 x 197mm 14 1 x 13 x 7 8 Weight 6 5kg 14 lbs 5 oz SPECIFICATIONS PANEL LAYOUT INPUT CH SELECT A B Channel Select Switch A B A Channel VOLUME No sound is produced when the VOLUME knob is set to 0 B Channel GAIN MASTER VOL No sound is produced when the MASTER VOL knob is set to 0 Tone Controls TREBLE MIDDLE BASS AUX IN Use the volume control on the audio device t...

Page 4: ...T SW CH A CLEAN IC1 IC2 CH A CLEAN CH B DRIVE CH B DRIVE B VOLUME GAIN MASTER FUSE FZ1 INDICATOR BASS MIDDLE TREBLE PASSIVE TYPE TONE CONTROL POWER SUPPLY CIRCUIT POWER TRANSFORMER VR1 VR2 VR3 VR4 VR5 VR6 4Ω Speaker PHONES AUX IN CN2 4P CN1 2P CN3 3P CN4 5P CN5 5P POWER SWITCH SW1 SW2 T2 T1 T4 T1 T2 G U C S BS MAIN 1 2 MAIN 2 2 T3 12V 12V 12V 12V 12V 12V 12V 12V B B JK3 JK2 JK1 V695450 Top View Si...

Page 5: ...me required about 3 min 3 1 Remove the pre main unit See procedure 1 3 2 Remove the six 6 knobs marked P100 and the six 6 hexagonal nuts marked C Fig 5 3 3 Remove the hexagonal nuts marked A120 and the hexagonal nuts marked A140 Fig 5 3 4 Push the hooks of the spacer support at the arrow symbol area of illustration with a needle nose plier to unlock The Main 1 2 circuit board can then be removed F...

Page 6: ...5 2 While pushing down the nut marked P70 with a spanner remove the two 2 screws marked P60 The power transformer can then be removed Fig 4 A120 Hexagonal Nut 9 0 12X2 MFNI33 LX200060 A140 Hexagonal Nut 12 0 14X2 MFNI33 ES200210 C80 Bind Head Tapping Screw 1 3 0X16 MFZN2BL EP030310 P70 Hexagonal Nut 1 4 0 MFZN2Y VB837300 P60 Pan Head Screw 4 0X10 MFZN2BL V7018000 P100 Knob V6955100 Fig 5 P60 P70 P...

Page 7: ...er to Main 2 2 CN5 from Power Transformer MAIN1 2 Circuit Board CIRCUIT BOARDS MAIN 1 2 J U CNA V733720 1 MAIN 1 2 H B CNA V733730 MAIN 2 2 J U CNA V733720 MAIN 2 2 H B CNA V733730 to MAIN 1 2 CN4 MAIN 2 2 Circuit Board Component Side Component Side VERSION FUSE RATE INDICATION J U 250V 500mA E BS 250V T160mAL Must be erased Must be erased ...

Page 8: ...sure that the low frequency is gradually emphasized or eliminated as you turn the BASS knob to the right or left 3 6 Make sure that the sound becomes larger when you depress the CH SELECT switch to select channel B Besides make sure that the sound becomes gradually distorted according as you turn the GAIN knob to the right 3 7 Make sure that the sound becomes gradually larger or smaller according ...

Page 9: ...racteristics are marked and must be replaced with parts having specifications equal to those originally installed The numbers in QTY shows quantities for each unit The parts with in Part No are not available as spare parts The second letter of the shaded part number is I not one The second letter of the shaded part number is O not zero ...

Page 10: ...F 20 2 OVERALL ASSEMBLY 60 20 10 C40 C60 C50 C60 C50 C30 C30 B A C20 C70 C90 C80 50 30 C120 C100 C110 OVERALL CABINET ASSEMBLY Pre Main Unit A Speaker Back Board Pre Main Unit See P 4 ...

Page 11: ...Truss Head Screw Flat Washer Label Label Label OVERALL CABINET ASSEMBLY Overall Cabinet Assembly Cabinet Assembly Corner Protector Oval Head Screw Handle Handle Holder Oval Head Screw Foot Bind Head Tapping Screw 1 Flat Washer Name Plate Bind Head Tapping Screw 1 Speaker Unit Bind Head Tapping Screw Bind Head Screw 4 0X25 MFZN2BL GA 10 3 0X12 MFZN2BL KPBO KAH1D 205 KPBO KAH3D400 A 4 0X30 MFZN2BL K...

Page 12: ...F 20 4 A10 A70 A60 A40 A10 A30 A80 A90 A20 P60 P40 P60 P30 P75 P70 P50 P10 P20 P90 P80 A50 P100 P120 P110 A100 A110 A130 A140 A120 PRE MAIN UNIT ...

Page 13: ...Spring Washer Pan Head Screw Button Knob Toothed Lock Washer B Earth Mark Amp Kit Amp Kit Amp Kit Amp Kit Circuit Board Circuit Board Insulation Sheet Sleeve Power SW Transformer Transformer Transformer Cord Holder Cord Cord Cord Cord Cord Strain Relief Cord Strain Relief Toothed Lock Washer A Flat Washer Hexagonal Nut Flat Washer Hexagonal Nut PINGOOD LCC 10 4 0X10 MFZN2BL 1 4 0 MFZN2Y 4 0 MFZN2Y...

Page 14: ...itor SL Electrolytic Cap Ceramic Capacitor SL Electrolytic Cap Electrolytic Cap Ceramic Capacitor B Electrolytic Cap Mylar Capacitor Mylar Capacitor Electrolytic Cap Electrolytic Cap Capacitor Monolithic Ceramic Cap Monolithic Ceramic Cap Electrolytic Cap Electrolytic Cap Electrolytic Cap Electrolytic Cap Base Post Connector Base Post Connector Base Post Connector Diode Diode Diode Stack Fuse Fuse...

Page 15: ...rbon Resistor Metal Oxide Film Resistor Metal Oxide Film Resistor Carbon Resistor Carbon Resistor Push Switch Transistor Rotary Variable Resistor Rotary Variable Resistor Rotary Variable Resistor Rotary Variable Resistor Rotary Variable Resistor Rotary Variable Resistor Zener Diode Zener Diode Connector Assembly Connector Assembly Connector Assembly Speaker Unit Power SW Transformer Transformer Tr...

Page 16: ...ER CH SELECT A B POWER ON OFF INPUT MIDDLE BASS TREBLE AUX IN PHONES 4Ω SPEAKER OP AMP OP AMP OP AMP OP AMP OP AMP OP AMP HIFI AMP KEC 54230 KEC 54230 1 1 J U C S BS 250V 500mA 250V T160mA L D2SBA20 VP344100 DIODE STACK 1 5A 200V DB1 WARNING Components having special characteristics are maked and must be replaced with parts having specification equal to those originally installed ...

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