Yamaha bx 1

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MONAURAL POWER AMPLIFIER

3 XS)

SERVICE MANUAL

I FRONT PANEL

1' 9??

m mm
m»; m m mu- am,

I REAR PANEL

9

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i):

m mm m mm an. mu (mu. 1! .- an my
Im. in (he .m Mm") . m. .I mm mm

(3

mm m "m... rm ox mm mm In:
E a I {IKE ms mum: In AMI II In)!
7 (-HHH )i W-
. 7 (LIIIIIIII g)
0 YAMAHA 235'? N
wovrxrs 45mm;
5 n em
Ell-:0! Ill EVA.

IIHIIHII

(III

OPOWER INDICATOR (POWER)

ePROTECTION INDICATOR (PROTECTION)
OSPEAKER IMPEDANCE INDICATOR (SQ/IODW)
OSPEAKER IMPEDANCE INDICATOR (4n/100W)
OSPEAKER TERMINALS (SPEAKER)

@GROUND TERMINAL (GND)

0 DC INPUT TERMINAL (INPUT DC)

eAC INPUT TERMINAL (INPUT AC)

9POWER INDICATOR

@POWER SWITCH (POWER)

(DSPEAKER SWITCH (SPEAKER)

@SPEAKER IMPEDANCE SELECTOR (IMPEDANCE) m
OCORD CLAMP _,.-, " '

SINCE 1867

YAMAHA

NlFFON GAKKI CO, LTD. HAMAMATSU. JAPAN
Printed in Japan 3,82 fi© 2.65K

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ICONTENTS
INTERNAL VIEW ................................................................ 1
1 DISASSEMBLY PROCEDURES ..................................................... 2 ~ 4
ADJUSTMENTS ................................................................ 5, 6
BLOCK DIAGRAM ............................................................... 7
SPECIFICATIONS ................................................................ 7
PRINTED CIRCUIT BOARD/WIRING ................................................... 8
SCHEMATIC DIAGRAM ............................................................ 9

' .INTERNAL VIEW

I
I

0PREDRIVE CIRCUIT BOARD @BOOTH BAR EARTH
QTROIDAL TRANSFORMER QFOWER ELECTROLYTIC CAPACITOR I47,000}1F 35V)
U.S. model: GA65650 @BAIAS POWER (+) CIRCUIT BOARD (1)
European modeI: GA65660 IDBAIAS POWER (+) CIRCUIT BOARD (2)
GMUTING CIRCUIT BOARD @POWER TRANSISTOR 2SC2565
0POWER SWITCH @POWER TRANSISTOR 25A1095
QPOWER PRIMARY FUSE {ISOUTPUT CIRCUIT BOARD ,.
QRELAY CIRCUIT BOARD (DBAIAS POWER (r) CIRCUIT BOARD (1)
ODIODE BRIDGE (PB-ISZFI @BAIAS POWER (-) CIRCUIT BOARD (2)