Technics SAEX-310 Service manual

ORDER NO. MD9707082C2

AV Control Stereo Receiver

*Manufactured under license from Dolby Laboratories Licensing Corporation. Additionally licensed under one or more of the following patents: U.S. numbers 3,632,886,3,746,792 and 3,959,590; Canadian numbers 1,004,603 and 1,037,877.

"Dolby" and the double-D symbol are trade marks of Dolby Laboratories Licensing Corporation.

Receiver

SA-EX310

Colour

(K) . . . . . . . . Black Type

Area

	Suffix for	Area	Colour
	Model No.
	(E)	Europe
	(EB)	Great Britain	(K)
	(EG)	Germany and Italy

SPECIFICATIONS\ТЕХНИЧЕСКИЕ ХАРАКТЕРИСТИКИ PROTECTION CIRCUITRY\ СИСТЕМА ЗАЩИТЫ

CAUTION FOR AC MAIN LEADS\ МЕРЫ БЕЗОПАСНОСТИ ПРИ РАБОТЕ СО ШНУРОМ ПИТАНИЯ ПЕРЕМЕННОГО ТОКА

OPERATION CHECKS AND MAIN COMPONENT REPLACEMENT PROCEDURES\ПРОВЕРКА РАБОТОСПОСОБНОСТИ И ЗАМЕНА ОСНОВНЫХ КОМПОНЕНТОВ

FAN MOTOR TROUBLESHOOTING\ НЕИСПРАВНОСТИ ДВИГАТЕЛЯ ОХЛАЖДЕНИЯ TROUBLESHOOTING\ НЕИСПРАВНОСТИ И МЕТОДЫ ИХ УСТРАНЕНИЯ

BLOCK DIAGRAM\ БЛОК-СХЕМА

TERMINAL FUNCTIONS OF IC's\ ФУНКЦИОНАЛЬНОЕ НАЗНАЧЕНИЕ ВЫВОДОВ ИНТЕГРАЛЬНЫХ МИКРОСХЕМ

TERMINAL GUIDE OF IC's, TRANSISTORS & DIODES\ ЦОКОЛЕВКА ВЫВОДОВ ИНТЕГРАЛЬНЫХ МИКРОСХЕМ, ТРАНЗИСТОРОВ И ДИОДОВ

SCHEMATIC DIAGRAMS\ ПРИНЦИПИАЛЬНЫЕ СХЕМЫ PRINTED CIRCUIT BOARDS\ ПЕЧАТНЫЕ ПЛАТЫ WIRING CONNECTION DIAGRAM\ СХЕМА СОЕДИНЕНИЯ

CABINET PARTS LOCATION\ РАСПОЛОЖЕНИЕ ЧАСТЕЙ КОРПУСА REPLACEMENT PARTS LIST\ СПИСОК ЗАПАСНЫХ ЧАСТЕЙ RESISTORS & CAPACITORS\ РЕЗИСТОРЫ И КОНДЕНСАТОРЫ PACKAGING\УПАКОВКА

© 1997 Matsushita Electronics (S) Pte. Ltd.

® All rights reserved. Unauthorized copying and distribution is a violation of law.

SA-EX310

Specifications

FM Tuner Section

Frequency range				87.50 — 108.00 MHz
Sensitivity				1.5 µ V / 75Ω
	S/N 30 dB
	S/N 26 dB			1.3 µ V / 75Ω
	S/N 20 dB			1.2 µ V / 75Ω
IHF	usable	sensitivity		1.5 µ V / 75Ω (IHF '58)
IHF	46 dB	stereo quieting	sensitivity	22 µ V /
				75Ω
Total harmonic distortion
	MONO			0.2%
	STEREO			0.3%
S/N
	MONO			60 dB (75 dB, IHF)
	STEREO			58 dB (71 dB, IHF)
Frequency response			20Hz — 15 kHz (+1dB, –2dB)
Alternate channel selectivity			+ 400 kHz	65 dB
Capture ratio				1 dB
Image rejection at 98MHz				40 dB
IF rejection at 98MHz				70 dB
Spurious response rejection at 98MHz				70 dB
AM suppression				50 dB
Stereo separation 1kHz				40 dB
Carrier leak
	19kHz			-30 dB (-35 dB, IHF)
IF rejection ( at 999 kHz )				55 dB

Amplifier Section

Power output		(at 240 V)		2 X 60 W(4Ω )
DIN 1 kHz (T.H.D. 1%)
	40 Hz–20 kHz continuous power output			2 X 40 W(8Ω )
	both channels driven
Total	harmonic		distortion	0.8 % (8Ω )
Rated power at 40 Hz – 20kHz
Half power at 1 kHz				0.07 % (8Ω )
Power output at the Dolby Pro Logic operation
DIN 1 kHz		( T.H.D. 1 % )		2 X 50 W (4Ω )
	Front
	Center			50 W (8Ω	)
	Surround			50 W (8Ω	)
Damping factor				30 (8Ω	)
Load	impedance			4 - 16 Ω
	Front
	Center			8 - 16 Ω
	Surround			4 - 16 Ω
Power bandwidth both channels driven, -3 dB 10 Hz - 40 kHz (8Ω)
Intermodulation			distortion rated	0.5 % (8Ω
power at 60 Hz : 7 kHz = 4:1, SMPTE					)
Frequency response
PHONO			RIAA standard curve(30Hz-15kHz) +0.8 dB
CD, TAPE, VCR, TV/DVD				10Hz – 40kHz, +3 dB
Input sensitivity and impedance				3 mV / 47 kΩ
PHONO
CD, TAPE, VCR, TV/DVD				200 mV / 22 kΩ
S/N at rated power ( 8Ω )
PHONO				70 dB (IHF, A: 80 dB)
CD, TAPE, VCR, TV/DVD				75 dB (IHF, A: 85 dB)

38kHz	-50 dB (-55 dB, IHF)
Channel balance (250 Hz - 6.3 kHz )	+1.5 dB
Limitting point	1.2 µ V
Bandwidth
IF amplifier	180	kHz
FM demodulator	1000	kHz
Antenna terminal(s)	75Ω (unbalanced)

Video Section

Output voltage at 1V input (unbalanced)	1±0.1 Vp-p
Maximum input voltage	1.5 Vp-p
Input/output impedance	75 Ω ( unbalanced)

AM Tuner Section

Frequency range	AM
	( 9 kHz steps )	522 — 1611 kHz
	( 10 kHz steps )	530 — 1620 kHz
Sensitivty		20 µ V, 330 µ V / m
Selectivity ( at 999 kHz )		55 dB
Image rejection	( at 999 kHz )	40 dB

Tone controls
BASS	50 Hz , +10 to -10 dB
TREBLE	20 kHz, +10 to -10 dB
Output voltage
TAPE REC (OUT), VCR OUT	200 mV
Channel balance (250 Hz - 6.3 kHz)	+ 1 dB
Channel separation	55 dB
Headphones output level and impedance	430 mV / 330 Ω
Subwoofer frequency responce	7 –100 Hz, + 3 dB

General

Power consumption		160 W
Power supply
E , EG	AC 230	V, 50 Hz
EB	AC 230 - 240	V, 50 Hz
Dimensions (W x H x D)	430 x 136 x 309 mm
Weight		7.3 kg

Notes :

1.Specifications are subject to change without notice. Weight and dimensions are approximate.

2.Total harmonic distortion is measured by the digital spectrum

Protection Circuitry

The protection circuitry may have operated if either of the following conditions are noticed:

•No sound is heard when the power is turned on.

•Sound stops during a performance.

The function of this circuitry is to prevent circuitry damage if, for example, the positive and negative speaker connection wires are "shorted", or if speaker systems with an impedance less than

the indicated rated impedance of the amplifier are used. If this occurs, follow the procedure outlines below:

1.Turn off the power.

2.Determine the cause of the problem and correct it.

3.Turn on the power once again after one minute.

Note:

When the protection circuitry functions, the unit will not operate unless the power is first turned off and then on again.

SA-EX310

Caution for AC Main Leads

(For “EB” area code model only.)

For your safety, please read the following text carefully.

This appliance is supplied with a moulded three pin mains plug for your safety and convenience.

A 5-ampere fuse is fitted in this plug.

Should the fuse need to be replaced please ensure that the replacement fuse has a rating of 5-ampere and that it is approved by ASTA or BSI to BS1362.

Check for the ASTA mark ASA or the BSI mark on the body of the fuse.

If the plug contains a removable fuse cover you must ensure that it is refitted when the fuse is replaced.

If you lose the fuse cover, the plug must not be used until a replacement cover is obtained.

A replacement fuse cover can be purchased from your local dealer.

CAUTION !

IF THE FITTED MOULDED PLUG IS UNSUITABLE FOR THE SOCKET OUTLET IN YOUR HOME THEN THE FUSE SHOULD BE REMOVED AND THE PLUG CUT OFF AND DISPOSED OFF SAFELY.

THERE IS A DANGER OF SEVERE ELECTRICAL SHOCK IF THE CUT OFF PLUG IS INSERTED INTO ANY 13-AMPERE SOCKET.

If a new plug is to be fitted, please observe the wiring code as shown below.

If in any doubt please consult a qualified electrician.

THIS PLUG IS NOT WATERPROOF—KEEP DRY.

Before use

Remove the connector cover.

How to replace the fuse

The location of the fuse differ according to the type of AC mains plug (figures A and B). Confirm the AC mains plug fitted and follow the instructions below.

Illustrations may differ from actual AC mains plug.

1. Open the fuse cover with a screwdriver. Figure A

Fuse cover

Figure B

IMPORTANT

The wires in this mains lead are coloured in accordance with the following code:

Blue: Neutral Brown: Live

As these colours may not correspond with the coloured markings identifying the terminals in your plug, proceed as follows:

The wire which is coloured Blue must be connected to the terminal which is marked with the letter N or coloured Black or Blue.

The wire which is coloured Brown must be connected to the terminal which is marked with the letter L or coloured Brown or Red.

WARNING: DO NOT CONNECT EITHER WIRE TO THE EARTH TERMINAL WHICH IS MARKED WITH THE LETTER E, BY THE EARTH SYMBOL OR COLOURED GREEN OR GREEN/YELLOW.

2.Replace the fuse and close or attach the fuse cover.

Figure A

Fuse

(5 ampere)

Figure B	Fuse
	(5 ampere)

SA-EX310

Operation Checks and Main Component Replacement Procedures

"ATTENTIONSERVICER" Some chassis components may have sharp edges. Be careful when disassembling and servicing. Please take note that the diagrams shown are for model SA-EX510 which is similar to SAEX310.

1.This section describes procedures for checking the operation of the major printed circuit boards and replacing the main components.

2.For reassembly after operation checks or replacement, reverse the respective procedures.

Special reassembly procedures are described only when required.

3. Select items from the following index when checks or replacement are required.

• Contents

	• Checking Procedure For Each Major P.C.B ........................................................................................				4 ~ 6
	•MainComponentReplacementProcedures........................................................................................				6~8
Checking Procedure For Each Major P.C.B.
1. Checking of the Panel P.C.B., andTuner P.C.B.
				a
				a
	Step 1			b
	a	X	Step 2
		4	b	X
		a		2
	PANEL P.C.B.
	(SolderSide)
IN/OUT TERMINAL P.C.B.					a
(SolderSide)				[SNE2129-1] (Black)
	TUNER P.C.B.				b
	(SolderSide)			[XTBS3+8JFZ1] (Black)
2. Checking of the In/Out Terminal P.C.B.
Step 1
Remove the top cabinet.			2
Step 3
Release the catch, pull				Catch
the rear panel in the
direction of arrow 1		and		Step 2
simultaniously	remove the
In/Out Terminal	P.C.B.	in		b	X 14
the direction of arrow		2
.	IN/OUTTERMINAL
	P.C.B.
			Catch

SA-EX310

	To Remove Front Panel, Panel P.C.B., Power Switch	Step 4
	P.C.B. and Headphone Jack P.C.B.
		Remove the Volume Knob

Step 1

Remove the top cabinet.

bX 3

Step 2

b

Step 3

Remove the front panel in the direction of arrow.

and Nut.	Step 6

c	c X	c	c
	18		c

Step 5

Pull out 3 knobs.

	c	c	c	c	c	d	X 1
b					Step 7
	Panel P.C.B.
Power Switch P.C.B.
					c
			[XTBS26+10J]
	Step 8				d
Headphone Jack P.C.B.	Pull out the Headphone
	Jack P.C.B.			[RHD26016]

3. Checking of the MAIN P.C.B.

	Step 1
	Remove the top cabinet.
	Step 2
	Remove the front panel.		b
			b
	Step 3		b
	f X	f	b
	13
		Step 5 b	X 4
		Step 7
	f	Lift the rear panel in the direction of arrow
		2 .
		2

catch

		Step 4
	f	e	X 4
				1
	Step 6
	Release 2 catches and pull the rear panel in			catch
	the direction of arrow		1 for about 10mm.

(Note : Main, Tuner and In/Out Terminal P.C.B. are attach to the rear panel)

SA-EX310

Step 8

Connect the front panel to the main P.C.B. as shown.

• Check the Main P.C.B. as shown

•

MAIN P.C.B. (Solder Side)

e

[XTB3+8FFZ] (Black)

f

[XTB3+20JFZ] (Black)

Main Component Replacement Procedures

1. Replacement of the Power IC and

Regulator Transistor

Step 1	Step 3 Fold the joints. (6 joints)
Remove the top cabinet.

Step 2 Cut the joints as shown below. (6 joints)

Step 4

Desolder the terminals of Power IC and

Regulator Transistor.

SA-EX310

Regulator transistor (Q701,Q708) [2SD2374PQAU,2SB1548PQAU]

Step 5	g	g	g
g X 3		Power IC (IC602)
			[XTW3+15T]
		[RSN3305-P]

Installation of the bottom cover after replacement

Step 1

*

h

Ribs

Lugs

Step 3

Screw (XTB3+8J)

(Prepare this screw to fix the bottom cover.)

Step 2

Align the ribs of bottom cover into the lugs.

h

[XTB3+8J] (Black)

CAUTION

1. After replacing the power IC or regulator transistor, apply a sufficient quantity of compound grease (RFKX0002/SZZ0L15) between the

heat	sink and the power IC or regulator transistor (Radiation
of power IC).	g

2.Tighten enough the screws ( ) after replacing the power IC and regulator transistor. Otherwise, the heat radiation works little.

3.When installing or removing the power IC or transistor holder, be sure to use an offset screwdriver.

•A long straight screwdriver cannot be used for removing or mounting the screws since its long grip interferes with the neighbouring P.C.B. and transformer.(See Fig.1 & 3)

•A short straight screwdriver may be used for removal, but cannot be used for mounting because the limited space in the unit will not allow sufficient tightening torque.(See Fig.2 & 3)

A short straight screwdriver	A long straight screwdriver
Fig.2	Fig.1

•Insufficient tightening will cause poor heat dissipation from the power IC and regulator transistor and,in the worst case, may lead to their thermal breakdown.

SA-EX310

Screws

AC In / Out

P.C.B.

Tuner & Tuner

Pack P.C.B.

Pro Logic

Transformer P.C.B.

P.C.B.

Power

P.C.B.

Fig.3

Front Panel	About 9 cm
	(A long straight screwdriver
	connot be used)

–––OFFSET SCREWDRIVER–––

•The PROTO offset screwdriver No.34-1/4 is recommended for use in the application above.

•The address of PROTO International Sales is as follows.

						Phone:	305-591-3828
				Japan		Europe
						Stanley-Proto Europe
				Stanley Works Japan		Woodside, Sheffield
				2-7-16 Hyakunin-Cho		539PD
International Sales				Shinjuku-ku		England
				Tokyo 160 Japan		Fax: [phone]
				Fax: [phone]		Phone:	44-742-768-888
International Sales Office		Singapore,	Indonesia,	Phone:	81-3-3360-
Stanley-Proto Industrial Tools		Philippines, Korea, Hong		8458		Canada
14117 Industrial Park Blvd.		Kong, Malaysia, China.		Mexico		Stanley-Proto Canada
Covington, GA 30209 U.S.A.		Stanley-Proto Asia Pacific				1100 Corporate Drive
Fax: [phone]		12 Gul Drive		Herramientas Stanley S.A.		Burlington, Ontorio
Phone:	706-787-3800	Singapore 2262		DE C.V.		Canada, L7L 5R6
		Fax: [phone]		Apartado Postal 675		Fax: [phone]
Australia, New Zealand &		Phone:	65-862-0883	72030 Puebla, Pue, Maxico		Phone:	416-335-0075
South Pacific				Fax: [phone]
Stanley-Proto Industrial Tools		Thailand		Phone:	52-22-495-300	Middel East, Mediterranean
P.O.Box 10		Stanley-Proto Thailand Ltd.		South & Central America,		& Africa
400 Whitehorse Road		1017 Moo 13 Bangkaew				Stanley-MEMA
Nunrweding 3131		Amphur Bangplee		Puerto Rico, The Caribbian		Cory House The Rlng
Victoria, Australia		Samutprakarn, Thailand		Stanley Inter-America		Bracknell Berkshire
Fax: [phone]		Fax: [phone]		2101 N.W. 84th Ave.		RG 12 1A2
Phone:	61-3-878-9244	Phone:	66-2-316-	Miami, Florida 33122		England
		8655		Fax: [phone]		Fax: [phone]
						Phone:	44-344-51813

SA-EX310

Fan Motor Troubleshooting

The Model SA-EX310 employ fan motor error sensing electronics.

If the cooling fan is not operating and "OVER LOAD" is displayed on the FL display, check the fan motor and its driving circuit.

"OVER LOAD" is displayed on the FL display.

Is the air
cooling path blocked		YES
or the fan motorjammed				Remove the obstacle.
by any external
obstacle ?
	NO
Remove the fan from the unit.

	Is the fan		NO			Fan motor failure
	motor's DC resistance
						Short circuit : DC resistance below 5Ω
	20 ~ 30Ω ?
						Open circuit : DC resistance over 1kΩ
		YES
	Reinstall the fan on the unit.

					Are the
				terminal voltage of
				Q772 and Q773 normal in both
				and inactive states of the
				fan motor ?
				(see table1.)
	(Voltage table)					YES
		fan. off		fan. on
	E	–14.5V		–14.5V
Q772	C	0V		–14.5V
	B	–14.5V		0V
	E	0V		–8.5V
Q773	C	–14.5V		–14.5V
	B	0V		–8.5V
		(Table 1)
				Is an audio signal
				present at pins 7 and 10
					of IC601

NO		Check the integrity of Q772, Q773 and the fan
		motor driving circuit. (see Fig.1)

		C772		35V4.7
			C771	50V4.7
D771 D772
1SS133
			R774	3.3M

+	R772
+	R771

47K 47K

		Q777	D774	1SS133
	Q778
R778 4.7K	R777	47K	Q776
R779	R773	10K		C773
10K
Q772		R775
		330
			R776
			4.7 1/4W

Q772,Q776

2SC1740SSTA

MOTOR DRIVE

Q777

2SA933SSTA

MOTOR DRIVE

Q778

RVTDTA114TST

MOTOR DRIVE

0.022

D773 MTZJ9R1CTA

C775

0.022

Q773

2SB621AQSTA

REGULATOR

Fig.1

NO

The power IC ( IC601 ) is defective.

CP771

FAN

M MOTOR

YES

The fan motor, power ICs and fan driver are functioning normally.

SA-EX310

Troubleshooting

This unit has test points on each circuit board block for use in troubleshooting.

CONNECTION

Connect either a CD player, tape deck or AF oscillator to the input terminals of the unit.

REQUIRED ITEMS

1.	Testing with a CD player	–––––––	Test disc (SZZP1054C / first progarm, 1kHz, 0dB)
2.	Testing with a tape deck	–––––––	Test tape (QZZCLA / 315Hz, 0dB)
3. Testing with a AF oscillator			–––––––	Set the output at 500Hz, 200mV
4.	Oscilloscope (min. 10MHz)		-----------	To measure the output waveform at the test points.

TEST PROCEDURE FOR AMPLIFIER CIRCUIT

	When the CD player AF oscillator is connected:			When the tape deck is connected:
Power on the unit.				Power on the unit.
Set the input selector button of the unit to the "CD" postion.				Set the input selector button of the unit to the "TAPE MONITOR"
Set the Speaker select buttons of the unit to the SPEAKERS "				postion.
ON" position.				Set the Speaker ON/OFF button of the unit to the SPEAKERS
				"ON" position.
	Run the CD player	or	Run the AF oscillator
				Run the tape deck
SZZP1054C / first program			Oscillator output
(	1kHz, 0dB	)	(at 500Hz, 200mV)	(315Hz,QZZCLA0dB)

Using the Oscilloscope, check the output waveforms at the test points on the circuit boards of the unit in the following order: (L1,R1) (L2,R2) (L3,R3) (L5,R5) (L6,R6).

Refer to page 10.

Note: Connect the '+' probe of the oscilloscope to each test point and the '–' probe to chassis ground.

TEST POINTS POSITIONS OF AMPLIFIER CIRCUIT

MAIN P.C.B. ( component side )

L6	J248	PANEL P.C.B. ( component side )
R6	J247

L3 R3

VR502

J318	L5		C1001
J319 R5		L1 +
		R1	+
		C1067	C1002
	L2
	R2	+C1004

SA-EX310

NORMAL WAVEFORMS OF AMPLIFIER CIRCUIT AND LIKELY FAULTY BLOCKS

Likely faulty block if the normal TP CD player Tape deck AF oscillator waveform shown at the left is not

present.

L1/R1			Input selector block IC402 &
area
0.5msec 2V	1msec 500mV	1msec 500mV
L2/R2			Dolby pro logic blockIC1001 and
			IC1002& area
0.5msec 2V	1msec 500mV	1msec 500mV
L3/R3			Master volume block VR501 &
			area
0.5msec 500mV	1msec 50mV	1msec 100mV
L5/R5			Power limiter block Q601 to
Q602				& area
0.5msec 100mV*	1msec 500mV	1msec 500mV
L6/R6			Main amplifier block IC601 &
				area
0.5msec 5V*	1msec 10V	1msec 10V
Measurement conditions.			•
			Volume control (VR501), Treble
control (VR512) and Bass control (VR511) positions			: •
*Volume control position (VR501) for these test			:

CHECKINGPROCEDUREFORSURROUNDCIRCUIT

Outputting surround signal normally requires that opposite phase signals be applied to both the left and right channels. However, this unit incorporates a service mode, allowing the surround circuit to be tested using in-phase signals.

When the CD player or AF oscillator is connected :	When the tape deck is connected :
Power on the unit.	Power on the unit.
Set the input selector button of the unit to the "CD"	Set the input selector button of the unit to the "TAPE
position.	MONITOR" position.
While pressing both "+" and "-" of the surround	While pressing both "+" and "-" of the surround
level adjustment button "SURROUND, press the	level adjustment button "SURROUND, press the
"Power" button.	"Power" button.
The letter SURROUND flash on the FL display.	The letter SURROUND flash on the FL display.

A

B

SA-EX310

A				B
				Run the tape deck
Run the CD player	Run the AF oscillator				(315Hz,QZZCLA0dB)
(SZZP1054C/first program)	(Oscillator output )
1kHz, 0dB	at 500Hz, 200mV
					Note: Connect the '+' probe of
Using the Oscilloscope, check the output waveforms at the test points on					the oscilloscope to each
the circuit boards in the following order :					test point and the '–'
(C1,S1)	(C2,S2)	(C3,S3)	(C4,S4)	(C5,S5).	probe to chassis ground.

• To exit the service mode, power off the unit.

TEST POINTS POSITIONS OF SOURROUND CIRCUIT

MAIN P.C.B. ( component side )

			C5	J246	PANEL P.C.B. ( component side )
			S5	J245
						S2
						C551 +
						C2
						R552
		C604
J316		+ S4
	C3	C603
J313	S3	+ C4
		S1 J22
		C1	J21
NORMAL WAVEFORMS OF AMPLIFIER CIRCUIT AND LIKELY FAULTY BLOCKS
						Likely faulty block if the normal
TP		CD player		Tape deck	AF oscillator	waveform shown at the left is not
						present.
C1						Dolby pro logic block
						IC1001 and IC1002 & area
S1
		0.5msec 1V		1msec 100mV	1msec 200mV
C2						Master volume block VR501 &
						area
S2
	0.5msec 200mV			1msec 20mV	1msec 50mV
C3						Tone control block IC551 & area
S3
	0.5msec 200mV*			1msec 500mV	1msec 1V

								SA-EX310
NORMAL WAVEFORMS OF AMPLIFIER CIRCUIT AND LIKELY FAULTY BLOCKS
							Likely faulty block if the normal
TP	CD player		Tape deck	AF oscillator			waveform shown at the left is not
							present.
C4							Power limiter block
							Q551 to Q552 & area
S4
	0.5msec 200mV*		1msec 500mV	1msec 1V
C5							Main amplifier block IC601 &
area							IC602 & area
S5
	0.5msec 5V*		1msec 10V	1msec 1V*
Measurement conditions.							•
					Volume control (VR501), Tremble
control (VR512) and Bass control (VR511) positions				:			•
	*Volume control position (VR501) for these test					:

CIRCUIT BLOCKS

OVERLOAD DETECTION FUNCTION

The HIC protection circuit functions if any cord at a speaker terminal is short-circuited or if the unit overheats because of improper operation. At the same time,OVERLOAD scrolls across the FL display.

In this state, all keys remain in operative; if any key is pressed, SWITCH OFF POWER scrolls across the FL display.

If an overload occurs, immediately power off the unit and check the speaker connection, venting holes and cooling fans. After fixing any faults, power on the unit again and check for proper operation.

If no defects are found, or if the unit remains overload after it is power on again, check the circuit for faults.

SA-EX310

Block Diagram