NAD M3 C/AH User manual

SERVICE MANUAL
SERVICE MANUAL
M3 C/AH
MODEL: M3SERVICE MANUAL
© NAD 2006
NAD ELECTRONICS INTERNATIONAL
TORONTO
M3 C/AH
Integrated Amplifier
M3 C/AH
Integrated Amplifier
Integrated Amplifier
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CONTENTS
SECTION 1 . . . .SUMMARY
SECTION 2 . . . .CABINET & MAIN CHASSIS
SECTION 3 . . . .ELECTRICAL
SECTION 4 . . . .REPLACEMENT PARTS LIST
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SECTION 1
SUMMARY
CONTENTS
PRODUCT SAFETY SERVICING GUIDELINES FOR AUDIO PRODUCTS ............. 1-2
SERVICING PRECAUTIONS ...........................................................................1-3
• General Servicing Precautions
• Insulation Checking Prodedure
• Electrostatically Sensitive Devices
SPECIFICATIONS ........................................................................................... 1-6,7
1-1
ALIGNMENT PROCEDURE ............................................................................. 1-4,5
• POWER DRIVEN VOLTAGE
• IDLING CURRENT
• BALANCE INPUTS CMRR
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1-2
SUBJECT: GRAPHIC SYMBOLS
PRODUCT SAFETY SERVICING GUIDELINES FOR AUDIO PRODUCTS
A.C. VOLTMETER
GOOD EARTH GROUND
SUCH AS THE WATER
PIPE. CONDUIT. ETC
PLACE THIS PROBE
ON EACH EXPOSED
METAL PART
CAUTION : DO NOT ATTEMPT TO MODIFY THIS
PRODUCT IN ANY WAY, NEVER PERFORM CUSTOM-
IZED INSTALLATIONS WITHOUT MANUFACTURER’S
APPROVAL. UNAUTHORIZED MODIFICATIONS WILL
NOT ONLY VOID THE WARRANTY, BUT MAY LEAD TO
YOUR BEING LIABLE FOR ANY RESULTING PROP-
ERTY DAMAGE OR USER INJURY.
SERVICE WORK SHOULD BE PERFORMED ONLY
AFTER YOU ARE THOROUGHLY FAMILIAR WITH ALL
OF THE FOLLOWING SAFETY CHECKS AND SERVIC-
ING GUIDELINES. TO DO OTHERWISE,INCREASES
THE RISK OF POTENTIAL HAZARDS AND INJURY TO
THE USER.
WHILE SERVICING, USE AN ISOLATION TRANS-
FORMER FOR PROTECTION FROM A.C. LINESHOCK.
SAFETY CHECKS
AFTER THE ORIGINAL SERVICE PROBLEM HAS
BEEN CORRCTED. A CHECK SHOULD BE MADE OF
THE FOLLOWING.
SUBJECT : FIRE & SHOCK HAZARD
1.BE SURE THAT ALL COMPONENTS ARE POSI-
TIONED IN SUCH A WAY AS TO AVOID POSSIBILITY
OF ADJACENT COMPONENT SHORTS.THIS IS ESPE-
CIALLY IMPORTANT ON THOSE MODULES WHICH
ARE TRANSPORTED TO AND FROM THE REPAIR
SHOP.
2. NEVER RELEASE A REPAIR UNLESS ALL PROTEC-
TIVE DEVICES SUCH AS INSULATORS, BARRIERS,
COVERS, SHIELDS, STRAIN RELIEFS, POWER
SUPPLY CORDS, AND OTHER HARDWARE HAVE-
BEEN REINSTALLED PER ORIGINAL DESIGN. BE
SURE THAT THE SAFETY PURPOSE OF THE POLAR-
IZED LINE PLUG HAS NOT BEEN DEFEATED.
3. SOLDERING MUST BE INSPECTED TO DISCOVER
POSSIBLE COLD SOLDER JOINTS, SOLDER
SPLASHES OR SHARP SOLDER POINTS. BE CER-
TAIN TO REMOVE ALL LOOSE FOREIGN PARTICLES.
4. CHECK FOR PHYSICAL EVIDENCE OF DAMAGE
OR DETERIORATION TO PARTS AND COMPONENTS.
FOR FRAYED LEADS, DAMAGED INSULATION
(INCLUDING A.C. CORD). AND REPLACE IF NECES-
5. NO LEAD OR COMPONENT SHOULD TOUCH A
RECIVING TUBE OR A RESISTOR RATED AT 1 WATT
OR MORE. LEAD TENSION AROUND PROTRUNING
METAL SURFACES MUST BE AVOIDED.
6. ALL CRITICAL COMPONENTS SUCH AS FUSES,
FLAMEPROOF RESISTORS, CAPACITORS, ETC.
MUST BE REPLACED WITH EXACT FACTORY TYPES,
DO NOT USE REPLACEMENT COMPONENTS OTHER
THAN THOSE SPECIFIED OR MAKE UNRECOM-
MENDED CIRCUIT MODIFICATIONS.
7. AFTER RE-ASSEMBLY OF THE SET ALWAYS PER-
FORM AN A.C. LEAKAGE TEST ON ALL EXPOSED
METALLIC PARTS OF THE CABINET, (THE CHANNEL
SELECTOR KNOB, ANTENNA TERMINALS. HANDLE
AND SCREWS) TO BE SURE THE SET IS SAFE TO
OPERATE WITHOUT DANGER OF ELECTRICAL
SHOCK. DO NOT USE A LINE ISOLATION TRANS-
FORMER DURING THIS TEST USE AN A.C. VOLTME-
TER, HAVING 5000 OHMS PER VOLT OR MORE SEN-
SITIVITY, IN THE FOLLOWING MANNER; CONNECT A
1500 OHM 10 WATT RESISTOR, PARALLELED BY A
.15 MFD. 150.V A.C TYPE CAPACITOR BETWEEN A
KNOWN GOOD EARTH GROUND (WATER PIPE,
CONDUIT,ETC.) AND THE EXPOSED METALLIC
PARTS, ONE AT A TIME. MEASURE THE A.C. VOLT-
AGE ACROSS THE COMBINATION OF 1500OHM
RESISTOR AND .15 MFD CAPACITOR. REVERSE THE
A.C. PLUG AND REPEAT A.C. VOLTAGE MEASURE-
MENTS FOR EACH EXPOSED METALLIC PART. VOLT-
AGE MEASURED MUST NOT EXCEED 75 VOLTS
R.M.S. THIS CORRESPONDS TO 0.5 MILLIAMP A.C
ANY VALUE EXCEEDING THIS LIMIT CONSTITUTES A
POTENTIAL SHOCK HAZARD AND MUST BE COR-
RECTED IMMEDIATELY.
THE LIGHTNING FLASH WITH APROWHEAD SYMBOL. WITHIN AN EQUILATERAL TRIANGLE, IS INTENDED
TO ALERT THE SERVICE PERSONNEL TO THE PRESENCE OF UNINSULATED “DANGEROUS VOLTAGE”
THAT MAY BE OF SUFFICIENT MAGNITUDE TO CONSTITUTE A RISK OF ELECTRIC SHOCK.
THE EXCLAMATION POINT WITHIN AN EQUILATERAL TRIANGLE IS INTENDED TO ALERT THE SERVICE
PERSONNEL TO THE PRESENCE OF IMPORTANT SAFETY INFORMATION IN SERVICE LITERATURE.
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SERVICING PRECAUTIONS
CAUTION:Before servicing the Stereo amplifier covered by
this service data and its supplements and addends, read and
follow the SAFETY PRECAUTIONS. NOTE: if unforeseen
circumstances create conflict between the following servicing
precautions and any of the safety precautions in this publication,
always follow the safety precautions.
Remember Safety First:
General Servicing Precautions
1. Always unplug the Stereo amplifier AC power cord from the
AC power source before:
(1) Removing or reinstalling any component, circuit board,
module, or any other assembly.
(2) Disconnecting or reconnecting any internal electrical
plug or other electrical connection.
(3) Connecting a test substitute in parallel with an electrolytic
capacitor.
Caution: A wrong part substitute or incorrect polarity
installation of electrolytic capacitors may result in an
explosion hazard.
2. Do not spray chemicals on or near this Stereo amplifier or
any of its assemblies.
3. Unless specified otherwise in this service data, clean
electrical contacts by applying an appropriate contact
cleaning solution to the contacts with a pipe cleaner,
cottontipped swab, or comparable soft applicator.
Unless specified otherwise in this service data, lubrication
of contacts is not required.
4. Do not defeat any plug/socket B+ voltage interlocks with
which instruments covered by this service manual might be
equipped.
5. Do not apply AC power to this Stereo amplifier and/or any
of its electrical assemblies unless all solid-state device heat
sinks are correctly installed.
6. Always connect test instrument ground lead to the
appropriate ground before connecting the test instrument
positive lead. Always remove the test instrument ground lead
last.
Insulation Checking Procedure
Disconnect the attachment plug from the AC outlet and turn the
power on. Connect an insulation resistance meter (500V) to the
blades of the attachment plug. The insulation resistance
between each blade of the attachment plug and accessible
conductive parts (Note 1) should be more than 1 M-ohm.
Note 1: Accessible Conductive Parts including Metal panels,
Input terminals, Earphone jacks, etc.
Electrostatically Sensitive (ES) Devices
Some semiconductor (solid state) devices can be damaged
easily by static electricity. Such components commonly are
called Electrostatically Sensitive (ES) Devices. Examples of
typical Es devices are integrated circuits and some field effect
transistors and semiconductor chip components.
The following techniques should be used to help reduce the
incidence of component damage caused by static electricity.
1. Immediately before handing any semiconductor component
or semiconductor-equipped assembly, drain off any
electrostatic charge on your body by touching a known earth
ground. Alternatively, obtain and wear a commercially
available discharging wrist strap device, which should be
removed for potential shock reason prior to applying power to
the unit under test.
2. After removing an electrical assembly equipped with ES
devices, place the assembly on a conductive surface such as
aluminum foil, to prevent electrostatic charge buildup or
exposure of the assembly.
3. Use only a grounded-tip soldering iron to solder or unsolder
ES devices.
4. Use only an antistatic solder removal device. Some solder
removal devices not classified a “anti-static” can generate
electrical charges sufficient to damage ES devices.
5. Do not use freonpropelled chemicals. These can generate
electrical charge sufficient to damage ES devices.
6. Do not remove a replacement ES device from its protective
package until immediately before you are ready to install it.
(Most replacement ES devices are packaged with leads
electrically shorted together by conductive foam, aluminum
foil, or comparable conductive material).
7. Immediately before removing the protective material from the
leads of a replacement ES device, touch the protective
material to the chassis or circuit assembly into which the
device will be installed.
Caution: Be sure no power is applied to the chassis or circuit,
and observe all other safety precautions.
8.Minimize bodily motions when handing unpackaged
replacement ES devices. (Normally harmless motion such as
the brushing together of your clothes fabric or the lifting of
your foot from a carpeted floor can generate static electricity
sufficient to damage an ES device.)
1-3
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321 123
ALIGNMENT PROCEDURE
A. POWER DRIVEN VOLTAGE(PSU BOARD)
Connect a DC Millivoltmeter to TP601/TP701 1 and 2 pin, then adjust VR601/VR701(6.8kohms)
for 0V±0.1V.
B. IDLING CURRENT(AMP BOARD)
1.Connect a DC Millivoltmeter betweenTP301 2 pins, then adjust VR301 (200ohms) for 7-8mV
reading on meter.
2.Connect a DC Millivoltmeter between TP401 2 pins, then adjust VR401 (200ohms) for 7-8mV
reading on meter.
3. Watch for 10minutes, to make sure it is arround 7mV
PSU BOARD
AMP BOARD(L/R)
1-4
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C. BALANCE INPUTS CMRR
1.Volum set 0dB, Input 2V/10KHZ common mode sinwave signal at L channel Balance input,Connect a AC
Millivoltmeter to preout1L then adjust R565 for lowest output level.
2. Volum set 0dB,Input 2V/10KHZ common mode sinwave signal at R channel Balance input,Connect a AC
Millivoltmeter to preout1R then adjust R564 for lowest output level.
1-5
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Power Amplifier Section
Continuous output power into 4/8 ohms 180W (17dBw)
(Minimum RMS power per channel, both channels
driven, With no more than the rated distortion)
Rated distortion (THD)(20Hz –20kHz) İ0.004%
Channel Separation ı100dB
(MAIN IN, 60W Out at 8,1kshorted, 1kHz)
Clipping power, 1kHz 220W
(Maximum continuous power per channel)
Dynamic Headroom at 8 ohms 4.2dB
Dynamic power 8ohms ı280W
(Maximum short-term power per channel ) 4ohms ı480W
2ohms ı785W
Damping factor ı150
Signal to noise ratio(refer 1W A-weighted) ıı100dB
Slew rate ıı20V/ȝsec
T.H.D and SMPTE I.M. İ0.01%
(Distortion from 250mW to rated output)
IHF I.M. (CCIF IM) and T.I.M distortion İ0.005%
(From 250mW to rated output))
Input impedance 20k//680pF
Input sensitivity rate power into 8ohms)roF( 1.38V
Power amp gain 29dB
Preamplifier Section
Input Impedance single-ended input 150k//500pF
SPECIFICATIONS
NAD M3 INTEGRATE AMPLIFIER
Note: Specifications are measured in accordance with EIA
Standard RS-490 (IHF A-202) for amplifiers
1-6
balanced input 120kS)
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Signal-to-Noise ratio 110dB ref 500mV
(A-weighted, line In, Pre-Out)
Rated distortion (THD)(20Hz –21kHz) İ0.005%
Channel Separation ı110dB
(1kHz 2V Line/balanced IN, 2V Pre-Out)
Input Sensitivity 320mV for 2V out
Input Overload Line input
Balanced input
ı10V
Frequency response(5Hz-70KHz) <+/-0.3dB
THD (SUB OUT) İ0.01%
(2V CD in, 2V SUB out; 50Hz, 80kHz LPF)
THD (ZONE 2 OUT)
(2V CD IN, 1kHz, 80kHz LPF) İ0.01%
Outputs
Preamp output impedance 
Zone2 output impedance 
Controls
Treble ±5dB at 10kHz
Bass ±5dB at 100Hz
Pre-in ,Power AMP out,input 2V
Signal-to-Noise ratio, A-weighted 107dB ref 1 W out
(500mV CD in, SPK out, 8, A weighted)
Rated distortion (THD)(20Hz –20kHz) İ0.008%
Input sensitivity 450mV
(CD in, SPK out, at rated power, volume max.)
Channel Separation ı100dB
(CD in, 20W out at 8, 1kshorted, 1kHz)
Frequency response Bd3.0-/+
1-7
ı9 V
PHYSICAL SPECIFICATIONS
Dimensions(W x H x D)
Net 17.2x5.3x15.2”(435x135x386mm)
Gross 17.2x5.8x17.2”(435x147x435mm)
Net Weight 51.8lbs(23.5kg)
Shipping Weight 68.3lbs(31.0kg)
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2-1
SECTION 2
CABINET & MAIN CHASSIS
CONTENTS
EXPLODED VIEWS.................................................................................. 2-2
1. Cabinet and main frame section...................................................................2-2
2. Packing accessory section............................................................................. 2-3
3. Exploded view parts list................................................................................. 2-4,5
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S023
PR10
PR07
PR08
PR09
PR11
PR12
S024
S015
S001
S020
C001
C002
C003
F001 F002 F003
F004
F005 F007
F008
F009 F010
F011
F012
C021
C004
C005
C006
C007
C010
C011
C012
C014
C015
C016
C015
C017
C013
R001
R002
R004
R006 R008
R007
R003
R005
C018 C019
C020
A001
A002 C022
C026
C009
C025
C008
PR01
PR02
PR03
PR04
PR06
T001
C027
PR05
C023
C024
C028
R009
A003
A004
A005
A006
S001
S001
S001
S002 S019
S002
S003
S004
S019
S005
S007
S006
S009
S008
S010
S004 S002
S011
S014
S013
S001
S018 S017
S016
S002
S004
S025
S022
S026
S016
S013
S025
S021
S004
F006
F013
R011
R010
C029
S012
S003
1. Cabinet and main frame section
2-2
EXPLODED VIEWS
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P006
P005
P001
P002
P003
P004
P008
P007
P011
P009
P013
P016
P015
P014
P012
P010
2. Packing accessory section
2-3
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REF.NO PART NO. DESCRIPTION Qty. REF.NO PART NO. DESCRIPTION Qty.
C001 lenaPraeR1-400840-761sissahC2-200840-76 ˄C˅1
C002 lenaPraeR2-410840-764knistaeH0-100840-07 ˄AH˅1
C003 01-50306-02 RAMP Board Assy 1 67-048024-0 Rear Panel˄CCC˅1
C004 01-50306-01 LAMP Board Assy 1 R002 01-50308-02 SPK Board˄R˅1
C005 01-50305-00 Power Board Assy 1 R003 01-50308-01 SPK Board ˄L˅1
C006 01-50307-02 StandbyBoard(Buttom) Assy 1 R004 77-048001-0 Bindingpost Plug Red(C) 4
C007 01-50307-21 StandbyBoard(Top) Assy 1 R005 17-03001-03 HS Bindingpost Red Assy 4
C008 01-50303-00 Connect Board Assy 1 R006 17-03001-04 HS Bindingpost white Assy 4
C009 01-50301-00 Balance Board Assy 1 77-048010-0 Double step washer Red 10
C010 01-50309-00 PREM Board Assy 1 77-048011-0 Double step washer White 10
C011 01-50312-00 Tone Board Assy 1 R008 69-048016-0 Counternut 20
C012 01-50311-00 L Input Board Assy 1 R009 77-048002-0 Bindingpost Plug White(C) 4
C013 94-048001-2 Transformer label 2 R010 11-01101-03 Power Switch 1
C014 68-048002-0 Shielding Box 2 R011 30-60480-00 RCA Shorting Plug 2
C015 Transformer rubber pad 4
C016 Transformer 2 A01 70-048005-0 Small Heatsink B 2
C017 2csiDlateM0-800100-66 A02 70-048004-0 Small Heatsink 2
C018 68-048001-1 HS Fixl Bar 4 A03 66-005009-0 Tr. Clamping 16
C019 4AraBsuB1-010840-96 A04 78-005005-0 Insulated Cashion 16
C020 4BraBsuB1-110840-96 A05 69-048024-0 Copper Spacer-Screw 16
C021 4yssAtooF0-010840-38 A06 66-018005-0 Tem. SW. Clamper 2
C022 75-048022-0 Bus Bar Washer 4
C023 1revoCCP0-210840-67 PR01 69-048032-0 Copper Spacer 2
C024 85-008001-1 Spacer Support 1 PR02 85-048001-0 Pcb Spacer 2
C025 69-048013-0 Copper Spacer 2 PR03 69-048027-0 PRE-BUSBAR L 1
C026 69-048031-0 Copper Spacer-Screw 4 PR04 69-048028-0 PRE-BUSBAR R 1
C027 66-011011-0 Connectible Bracket 2 PR05 17-01001-16 HS RCA Red Assy 10
C028 66-048004-0 Balance pcb Shielding 1 PR06 17-01001-15 HS RCA White Assy 10
C029 1telnIC
A00-20170-71 PR07 Pre. Module pcb Down 2
PR08 Pre. Module pcb Up 2
F001 71-048010-0 Vol. Knob Assy 1 PR09 70-048002-0 Module Base 2
F002 70-048011-0 M3 Fascia 2 1 PR10 70-048003-0 Module Cover 2
F003 01-50302-00 Encoder Board Assy 1 PR11 66-048001-0 Tr. Bracket 4
F004 76-048010-0 Window lens 1 PR12 78-048004-0 Insulated Cashion 8
F005 70-048013-0 Power Button 1
F006 1sneLDEL1-100800-67 S001 61-023208-0 Screws, BTB3×8 35
F007 92-048001-0 Spring for Button 8 S002 61-224512-1 Hex Screws 4×12 51
F008 87-048002-0 Input Button Pad 7 S003 61-224508-1 Hex Screws 4×8 10
F009 70-048012-1 Input Button 7 S004 61-023206-0 Screws, BTB3×6 40
F010 01-50304-00 FPP Board Assy 1 S005 62-010802-0 Nut M8 2
F011 70-048010-1 M3 Fascia 1 1 S006 63-020820-1 Spring Washers ij82
F012 1aicsafbuS1-300840-7
6S007 63-010816-0 Washers ij82
F013 87-048003-0 Power Button Pad 1 S008 63-020616-0 Spring Washers ij68
S009 61-226510-0 Hex Screws 6×10 8
1revoCpoT0-100840-76100T S010 64-208070-0 Bolts M8×70 2
3. Exploded view parts list
R007
R001
16-53013-00
18-53231-01
2-4
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REF.NO PART NO. DESCRIPTION Qty. REF.NO PART NO. DESCRIPTION Qty.
S011 61-023212-0 Screws, BTB3×12 2
S012 62-050302-0 PEM NUT-PCB M3×0.5 16
S013 61-223506-1 Hex Screws w/Tooth washer 24
S014 61-223514-0 Hex Screws 3×14 16
S015 61-023106-0 Screws, STB3×6 4
S016 61-373506-0 Machine Screws M3×6 14
S017 63-010408-0 Spring Washers ij42
S018 62-010402-0 Nut M4 2
S019 61-024108-0 Screws, STB4×8 4
S020 63-020411-0 Washers ij42
S021 62-010302-1 Nut M3 6
S022 61-023506-1 Screws, MB3×6 16
S023 61-062206-1 Screws, BTF2×6 8
S024 61-062108-1 Screws, STF2×8 4
S025 61-023508-0 Screws, MB3×8 10
S026 61-022206-0 Screws, BTB2×6 8
P001 88-048001-0 Shipping Box 1
P002 1xoBtfiG0-200840-88
P003 89-048001-0 Polyfoam-Bottom 1
P004 89-048002-0 Polyfoam-Cap 1
P005 87-048004-0 Non-woven-cloth Bag 1
P006 1gabyloP0-100500-09
P007 88-043003-0 Accessories Box 1
30-45030-11 Instruction Manual 1
30-45030-02 Instruction Manual 1
30-45030-03 Instruction Manual CCC 1
P009 89-048003-0 Little Polyfoam A 1
P010 30-28601-00 Batteries CR2025 1
P011 30-10300-00 Remote Control 1
P012 1teehS
xoB0-400340-88
1CdroCCA00-05201-51
15-10125-00 AC Cord AH
15-10250-03 AC Cord CCC 1
P014 30-17200-01 Remote Control ZR3 1
P015 89-048004-0 Little Polyfoam B 1
P016 30-22100-00 Batteries AA 2
P008
P013
Packing List
2-5
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SECTION 3
ELECTRICAL CONTENTS
ELECTRICALTROUBLESHOOTING GUIDE
1. Power check flow
2. Preamp operation flow
DETAILS AND WAVEFORMS ON SYSTEM TEST AND DEBUGGING
1. SYSTEM 11MHz CLOCK
2. AT89C51 reset signal
3. Volume control DATA and CLOCK
4. REC(ZONE) select DATA and CLOCK
5. Input select DATA and CLOCK
BLOCK DIAGRAMS
1. POWER DISTRIBUTE DIAGRAM
2. PREAMP SIGNAL PATH
3. SYSTEM CONTROL PATH
CIRCUIT DIAGRAMS
1. POWER AMPLIFIER BOARD Circuit DIAGRAM
2. PREAMP BOARD Circuit DIAGRAM
3. STANDBY AND SPEAKER BOARD Circuit DIAGRAM
4. ENCODER AND CONNECT BOARD Circuit DIAGRAM
5. FRONT PANEL BOARD Circuit DIAGRAM
6. BALANCE INPUT BOARD Circuit DIAGRAM
7. POWER BOARD Circuit DIAGRAM
PRINTED CIRCUIT DIAGRAMS
1. Preamp Main board(PREM)
2. Preamp LCH input board(PREL)
3. Preamp tone control board(PRET)
4. Power supply board(PSU)
5. Balance amplifier board(BAL)
6. Connect board(CON)
7. Encoder board(ENC)
8. Speaker board(SPK)
9. Front pannel board(FPP)
10. Standby board Bottom(STBB)
11. Standby board top(STBT)
12. Left Channel PCB
3-2
3-2,3
3-4,5
3-6
3-6
3-6
3-7
3-7
3-8
3-9
3-9
3-10
3-11
3-12
3-12
3-13
3-14
3-15
3-16
3-17
3-18
3-19
3-19
3-20
3-20
3-21
3-22
3-23
3-23
3-23
3-24
3-25
3-26
3-27
3-28
3-29
3-1
13. Right Channel PCB
14. Preamp Module PCB
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1.Power Check Flow
Power switch on
Amber LED ON? NO
Check S1 and its cable
Check F901
Check the standby Transformer
Check IC1 on the standby board
YES
Hear the relay’s click? NO
Check the MCU on the keyboard
Check Q91 Q92 and OP91
Check if the main transformers
has been plugged in
YES
+/-70V
un-regulated power supply
is correct?
NO
Press the standby button
A
ELECTRICAL TROUBLESHOOTING GUIDE
5V is Right ? NO
YES
Check the MCU on the keyboard
Check U84 and Q82
Check the D81
Check F902 and F903
Check the main transformer
Check B603 B604 B703 B704
Check D602 D603 D702 D703
Check PSU PCB
YES
+/-20V
power supply is correct? NO
Check R648 R649 R748 R749
Check B605 B705
Check IC603 IC604 IC703 IC704
Check the PCB track
YES
+/-18V
power supply is correct? NO Check the sockets and plugs
Check 1Q21 1Q22 2Q21 2Q22
YES
3-2
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NO
YES
12V on the
preamp relayis correct?
NO Check Q990 Q991
Check D990 D991
YES
A
+72V
power supply is correct?
Check R646 R647 R746 R747 R622
Check B606 B706
Check Q609 Q610 Q611
Check the PCB track
THE END
YES
-72V
power supply is correct? NO Check R623
Check Q612 Q613
3-3
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2.Preamp operation flow
Power on
Amber LED change to
blue?
NO Check FPP board
YES
Hear the relay’s click? NO Check 24V relay suply
Check U113,U108,U213,U208
Check HCLK,HDATA,FUNC signal
YES
Relay respond properly? NO
YES
Wate for 10 second
Press listen,mode,biamp key
to change input and out put
mode
Input 2V RMS 1K sinewave,turn
volume to 0dB,measure
preoutput level and THD
Level=2V±0.1V ?
B
Check U105,U205,U104,U107,U204,U207
Check VOL_ CLK,STB,DATA(L/R) signal
Check VOLA signal and 1Q28
Check Q103,Q203,Q101,Q102,Q201,Q202
Check U101,U201,U106,U206
YES
THD>0.01%?
NO
YES
NO
3-4
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NO
YES
B
Response change properly?
Check U112,±17V at tone board
Check TONE_STB,OPSEL_DATA
OPSEL_CLK signal
THE END
Press Tone Key to change
tone setting,measure preout
response
YES
Level=2V±0.1V
THD<0.03%?
NO Check U109 U209 U111 U211
Check OPSEL_STB signal
Press Z-2/record key to current
input channel then measure
output level and THD
3-5
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DETAILS AND WAVEFORMS ON SYSTEM TEST AND DEBUGGING
1. SYSTEM 11MHz CLOCK
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2. AT89C51 reset is high active.
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3-6
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