Yamaha A-s300 Service Manual

							11
A-S500/A-S300
A-S500/A-S300
OPERATION (1) P.C.B.
MAIN (6) P.C.B.
MAIN (5) P.C.B. (J model) 
OPERATION (7) P.C.B. (R model)
MAIN (2) P.C.B.
DOCK P.C.B.
FUNCTION (2) P.C.B.
FUNCTION (3) P.C.B. 
FUNCTION (1) P.C.B. 
MAIN (4) P.C.B.
MAIN (1) P.C.B.
MAIN (3) P.C.B.
POWER TRANSFORMER
OPERATION (11) P.C.B.
OPERATION (8) P.C.B.
OPERATION (6) P.C.B.
OPERATION (3) P.C.B. 
OPERATION (4) P.C.B.
OPERATION (5) P.C.B.
OPERATION (9) P.C.B.
OPERATION (2) P.C.B.
OPERATION (10) P.C.B. Top view
Front view1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22 9 11
21 2213 1012
12
14 16 17 18 2019 1534 5 87 6
■ INTERNAL VIEW
■  SERVICE PRECAUTIONS / 
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Safety measures
•  Some internal parts in this product contain high voltages 
and are dangerous. Be sure to take safety measures 
during servicing, such as wearing insulating gloves.
•  Note that the capacitors indicated below are dangerous 
even after the power is turned off because an electric 
charge remains and a high voltage continues to exist 
there.
Before starting any repair work, connect a discharging 
resistor (5k-ohms/10W) to the terminals of each 
capacitor indicated below to discharge electricity. The 
time required for discharging is about 30 seconds per 
each.
C134, C135 on MAIN (1) P.C.B.
For details, refer to “PRINTED CIRCUIT BOARDS: MAIN 
(1) P.C.B.”.
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							12
A-S500/A-S300
A-S500/A-S300
Top cover
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Front panel unit
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Knob VOL
ÊÒ70- Knob INPUT
ÊÒ*/165 Knob TC
ÊÒ5$ Knob SP13
ÊÒ41 Cap POWER
©ß¿Ó108&3
Cap DIRECT
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Frame top

						

							13
A-S500/A-S300
A-S500/A-S300
Sub-chassis unit
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Hook
Ñ¿«
Hook
Ñ¿«FUNCTION (1) P.C.B. DOCK P.C.B.FUNCTION (2) P.C.B.
FUNCTION (3) P.C.B.
CB101CB108 CB503
CB2CB21CB14CB506
CB504CB505
CB706
CB853CB854 CB851
Š
ŠŒ
‹
Fig. 3 Fig. 2
3.  Removal of Sub-chassis Unit
a.  Remove 2 screws (
Š). (Fig. 2)
b.  Remove CB101, CB108, CB503-505, CB706, CB851 
and CB853-854. (Fig. 2)
c.  Release 2 hooks and then remove the sub-chassis 
unit. (Fig. 2)
4.  Removal of FUNCTION (1)–(3) and DOCK P.C.B.s
a.  Remove 8 screws (
‹). (Fig. 3)
b.  Remove screw (
Œ) and screw (
). (Fig. 2)
c.  Remove CB2, CB14, CB21 and CB506. (Fig. 2)
d.  Remove the FUNCTION (1)–(3) P.C.B.s and DOCK 
P.C.B. together. (Fig. 2)

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							14
A-S500/A-S300
A-S500/A-S300
Ground lead
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¢Sub-chassis unit
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Rubber sheet and cloth

						

							15
A-S500/A-S300
A-S500/A-S300
Chassis cover
³ß”³§Ì”
Rubber sheet and cloth
° Ü ³ ”Äq 
ÍŽŽŽ
MAIN (1) P.C.B.
Fig. 5
When checking the MAIN (1) P.C.B.:
•  Spread the rubber sheet and the cloth. Then place 
this unit on the cloth upside down. (Fig. 5)
•  Remove 6 screws (
Ž) and then remove the chassis 
cover. (Fig. 5)
.*/
						

							16
A-S500/A-S300
A-S500/A-S300
When the following parts are replaced, the firmware must 
be updated to the latest version.
FUNCTION P.C.B.
Microprocessor (IC502: FUNCTION P.C.B.)
●  Confirmation of firmware version
Before and after updating the firmware, check the 
firmware version by using the self-diagnostic function 
menu.
Start up the self-diagnostic function, have the 
firmware version displayed, and note them down.
(See “SELF-DIAGNOSTIC FUNCTION”)
*  When the firmware version is different from written 
one, perform the UPDATING FIRMWARE from the 
beginning.
●  Initializing the back-up IC
(EEPROM: IC503 of the FUNCTION P.C.B.)
After updating the firmware, the back-up IC MUST be 
initialized by the following procedure to have proper 
memorization of the set up information.
Start up the self-diagnostic function.
(See “SELF-DIAGNOSTIC FUNCTION”)
Set the SPEAKERS selector to the “A” position, press 
the “
” (power) key to turn off the power once and 
press the “
” (power) key to turn on the power again.
Then the back-up IC is initialized.
● Required Tools
•  Firmware downloader program
FlashSta.exe
• Firmware
ASx00_xxx.mot
ASx00_xxx.id
•  RS-232C cross cable “D-sub 9 pin female”
(Specifications)
•  RS-232C conversion adaptor (Part No.: WR492800)
■  UPDATING FIRMWARE / 


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							17
A-S500/A-S300
A-S500/A-S300
Serial port (RS-232C)³æžç Ù ”Ä
						

							18
A-S500/A-S300
A-S500/A-S300
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							19
A-S500/A-S300
A-S500/A-S300
Fig. 4
Fig. 5
115200
40
5.  Click [Setting], and set the baud rate. (Fig. 4)


						

							20
A-S500/A-S300
A-S500/A-S300
10. Disconnect the power cable of this unit from the 
AC outlet.
11. Remove the RS-232C conversion adaptor and 
flexible flat cable from the writing port of this unit.
12. Connect the power cable of this unit to the AC 
outlet, start up the self-diagnostic function and 
check that the firmware version is the same 
as written one. (See “Confirmation of firmware 
version”)