Yamaha Bass Amplifier service manual F-20B 4.MAIN 2/2 Circuit Board, Time required about 3 min

F-20B

4.MAIN 2/2 Circuit Board

(Time required: about 3 min)

4-1 Remove the pre-main unit. (See Procedure 1)

4-2 Remove the screw marked [C80]. The MAIN 2/2 circuit board can then be removed. (Fig.3, Fig.5)

5.Power Transformer (Time required: about 4 min)

5-1 Remove the pre-main unit. (See Procedure 1)

5-2 While holding the nuts marked [P70] with a spanner, remove the two (2) screws marked [P60]. The power transformer can then be removed. (Fig.4)

MAIN1/2 Circuuit Board

[P70] [P60]

Power Transformer

[P80]

MAIN1/2 Circuuit Board

(Fig. 3)	(Fig.4)
	Power Transformer

MAIN 2/2

[P40] [P80] [P70] [P60]

[P40] [P60] [P70]

MAIN 1/2

[A120] [P100], [C] [A140]

[A120]: Hexagonal Nut 9.0 12X2 MFNI33 (LX200060)

[A140]: Hexagonal Nut 12.0 14X2 MFNI33 (ES200210)

[P60]: Pan Head Screw 4.0X10 MFZN2BL (V7018000)

[P70]: Hexagonal Nut #1 4.0 MFZN2Y (VB837300)

[P80]: Bind Head Screw-1 3.0X16 MFZN2BL (V7018100)

[P100]: Knob (V6955100)

(Fig. 5)

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