Ecler MPA4-400 User manual

MPA4-400
SERVICE MANUAL
100 0 10 0 10 0
POWER
10
OFF
ON
CHANNEL 4
VOL
5
CLIP SP
CHANNEL 1 CHANNEL 3
5
SP
5
CLIP
CHANNEL 2
CLIP SP
5400
MULTICHANNEL
POWER AMPLIFIER
MP
THERMAL SP CLIP
LECRE
A4-
VOLVOLVOL
MAINS INPUT
GND
XLR CONNECTIONS: PIN 1 - GROUND, PIN 2 - PHASE, PIN 3 - NON PHASE
IN 2
LINK CH 1
LINK CH 2
IN 4
BRIDGE IN 3
BRIDGE
OFFON
IN 3+IN 4
GND LINK
STEREO
BRIDGE
IN 1+IN 2
ON IN 4
CHANNEL 4
HP FILTER
OFF
ON
OFF
IN 2
BRIDGE IN 1
STEREO
CHANNEL 2
LP FILTER IN 1
IN 3 LINK CH 1
CHANNEL 3
IN 1
IN 3
IN 1+IN 2
CHANNEL 1
CH 2 -
CH 2 +
MINIMUM LOAD: 4 OHM STEREO, 8 OHM BRIDGE
FOR BRIDGED OUTPUT USE RED POSTS ONLY.
OUTPUT
BRIDGED
CH 3 -CH 4 -
CH 4 + CH 3 +
BRIDGED
CH 1 -
CH 1 +

SERVICE MANUAL MPA4-400
INDEX
-BLOCK DIAGRAM
-FUNCTIONING DESCRIPTION
-SCHEMATICS
Power amplifier
Inputs
Power Supply + Outs
Leds + potentiometers
-COMPONENTS LOCATION SCHEMA
Power amplifier
Power Supply + Inputs + Outs
Leds + potentiometers
-TESTING AND QUALITY CONTROL
-TECHNICAL CHARACTERISTICS
-WIRING DIAGRAM
-CONFIGURATION DIAGRAM
-MECHANICAL DIAGRAM
-PACKING DIAGRAM

52-0017-0100 EP14-02.doc 1 of 2
The amplifying stage basic structure is actually the one commonly used until now, this is,
a push-pull mounted A-B class amplifier, using P-type (IRFP9240) and N-type (IRFP240)
mosfets.
The system's controlling core is a NE5534 OpAmp, which is internally compensated in
order to obtain an amplifying gain ratio equal or greater than 3. The amplifier's feedback
runs through a resistor and a capacitor associated to the OpAmp's non-inverting input.
Transistors BF871 and BF872 are common-base configured, becoming actually a current
source structure. They accomplish a dual function: on one hand, they polarise the mosfet's
gate-source junction, keeping them on their conduction knee. On the other hand, they
carry out the OpAmp's output voltage variations, referred to signal ground.
The polarisation current adjustment is fixed by a 2k5 trimming potentiometer connected to
the BF transistors base. This current is added to the current source's output, which passes
through the BF-transistors load resistors. The bias current stability against temperature is
fixed through the BD437 transistors. Their temperature- dependent base-emitter voltage
curve is used to alter adequately the current source's reference voltage. As a
consequence, if the temperature rises, the reference voltage decreases, thus the gate-
source voltage also does, and finally the bias current also decreases.
The Zobel network, formed by a resistor-inductor-capacitor group, and which is located at
the amplifier's output, intends to keep the amplifier's load impedance as constant as
possible, no matter which load is connected to the stage's output, or which signal
frequency is to be amplified, in order to prevent an inverted-phase feedback signal.
In order to avoid a DC offset on the output signal, a diac-triac tandem system is used,
which shorts the output to signal ground when the DC level is enough to get the diac
triggered. To prevent this from happening while carrying audio signal (sine-wave, music),
the diac's reference voltage is taken from a filter formed by resistor R161 and capacitor
C123.
The protection circuitry supervises at any time the power consumed by the MOSFETS. The
circuitry basically consists on two sections: MOSFET's drain current (Id) monitoring and
drain-source voltage (Vds) monitoring.
When the drain current exceeds a certain limiting value, a transistor (called control-
transistor) becomes conducting, together with an auxiliary circuitry (helper), formed by a
transistor (which is the same type as the control-transistor) and a 8'2V Zener diode. This
value determines the point where the auxillary circuitry starts to run. The helper-
transistor's base-emitter junction curve is used to obtain a non-linear variation on the
MOSFETS gate-source voltage control, and thus on their drain current.
author: Queralt date: 020927 project:
EP14-02
product:
MPA4-400
E
C
LER approved:
num: 52..0017 version: 01.00
title:
FUNCTIONING DESCRIPTION

52-0017-0100 EP14-02.doc 2 of 2
Moreover, as the helper-transistor's base-emitter current is temperature-dependent, the
controlling circuitry (basically the control-transistor) compensates the safe operation area
(SOA) drift due to temperature.
If the MOSFET's drain-source voltage (Vds) drops too low, a second circuitry actuates to
alter the control-transistor's triggering level, obtaining a SOA-like curve section and a
current stage, which can be adjusted adequately in order to maintain the MOSFET's power
consumption as close as possible to its SOA.
Moreover, the amplifier also includes an ANTICLIP system.
When the amplifier reaches its clipping level, the OpAmp becomes unable to keep the
system under control, and as a consequence ±V peaks appear at its output (15V power
supply). This peaks are used to be rectified and sent to an optocupler (led-resistor) which
modifies its impedance as a function of those peaks' amplitude. The resulting impedance is
part of a voltage divider, together with the amplifier's input impedance. So, as the
optocoupler increases its impedance, the amplifier's input signal level decreases until the
system becomes stable.
Also a dual-function temperature control circuitry is provided:
- Temperature-depending control of the cooling fan speed, whose voltage supply is variable
between 7 and 14 Vac.
- Amplifier shutdown when temperature exceeds approximately 90ºC.
The circuitry is formed by LM35D-type IC, which acts like a thermal probe, an amplifier,
thermal probe level comparator and a 7805-type voltage regulator.
The amplifier is responsible for the cooling fan speed control. The comparator triggers a
relay, which cuts off the MOSFETs' bias current by shunting a 22Ωresistance to the BF-
type transistors' load resistors. This way, the output signal of the amplifier is effectively
cutted off.
The STAND-BY circuit.
This circuit keeps the safety relay closed for about 10 seconds, thus the MOSFET's bias
current is cutted off during this period, until the whole system reaches again a voltage-
stable situation. Due to this, hearing annoying transients and noises during start up
through the loudspeakers is avoided. This delay is obtained by a RC-cell, where R=287K,
and C=47µF/50V. During start up, this RC-cell's voltage smoothly rises until the 40106-
type Trigger-Schmitt trigging level is reached, and the amplifier starts functioning. C=47µF
resets or discharges when the unit is turned off. During a short period of time, a BC817-
type transistor acts like a switch, connecting two 75Ωparallel resistors to C=47µ/50V.

PARTS LIST: PRINTED CIRCUIT 11.0956.03.01
Code
Description
Reference
FCXCD12200
22p
C101
FCXCD41000
100n
C102
FCXCD41000
100n
C103
FCCE250100
10u/50
C104
FCCE250470
47u/50
C105
FCXCD16800
68p
C106
FCXCD16800
68p
C107
FCCE350470
47u/100
C108
FCCE350470
47u/100
C109
FCCE250100
10u/50
C110
FCXCD41000
100n
C111
FCXCD11500
15p
C112
FCXCD41000
100n
C113
FCCE250100
10u/50
C114
FCXCD44700
470n
C115
FCXCD44700
470n
C116
FCXCD11500
15p
C117
FCXCD11500
15p
C118
FCCDK52200
C220n/100V
C119
FCCDK52200
C220n/100V
C120
FCXCD26800
680p
C121
FCXCD26800
680p
C122
FCCDK20010
C1u/63V
C123
FCXCD40100
10n
C124
FCXCD40100
10n
C125
FCCDH71100
C100n/400V
C126
FCCDH71047
C47n/400V
C127
FCXCD41000
100n
C128
FCXCD41000
100n
C129
FCXCD41000
100n
C130
FCCE250100
10u/50
C131
FCXCD44700
470n
C132
FCCE250100
10u/50
C133
FCCE100000
47u/16
C134
FCXCD44700
470n
C135
FCCE250470
47u/50
C136
FCCE250470
47u/50
C137
FCCE250100
10u/50
C138
FCCE154700
470u/25
C139
FCXCD12200
22p
C140
FCXCD41000
100n
C141
FCXCD41000
100n
C142
FCCE250100
10u/50
C143
FCCE250470
47u/50
C144
FCXCD16800
68p
C145
FCXCD16800
68p
C146
FCCE350470
47u/100
C147
FCCE350470
47u/100
C148
FCCE250100
10u/50
C149
FCXCD41000
100n
C150
FCXCD11500
15p
C151
FCXCD41000
100n
C152
FCCE250100
10u/50
C153
FCXCD44700
470n
C154
FCXCD44700
470n
C155
FCXCD11500
15p
C156
40-0113-0105 EP14-02 MPA4-400.xls 1 of 10

PARTS LIST: PRINTED CIRCUIT 11.0956.03.01
Code
Description
Reference
FCXCD11500
15p
C157
FCCDK52200
C220n/100V
C158
FCCDK52200
C220n/100V
C159
FCXCD26800
680p
C160
FCXCD26800
680p
C161
FCCDK20010
C1u/63V
C162
FCXCD40100
10n
C163
FCXCD40100
10n
C164
FCCDH71100
C100n/400V
C165
FCCDH71047
C47n/400V
C166
FCCE100000
47u/16
C167
FCCE250470
47u/50
C168
FCXCD41000
100n
C169
FCPERL2550
Cer. Bead
CB101
FCPERL2550
Cer. Bead
CB102
FCPERL2550
Cer. Bead
CB103
FCPERL2550
Cer. Bead
CB104
FCCI009560
Printed Board 11.0956
CI101
FCXDDBAS28
BAS28
D101
FCXZ000075
Z7.5V
D102
FCXDDBAS28
BAS28
D103
FCXZ000039
Z3.9V
D104
FCXZ000039
Z3.9V
D105
FCLEDSMD20
TLMH3101
D106
FCLEDSMD20
TLMH3101
D107
FCDD041200
Z12
D108
FCDD041200
Z12
D109
FCDD041200
Z12
D110
FCDD041200
Z12
D111
FCDD041200
Z12
D112
FCDD041200
Z12
D113
FCXZ000180
Z18V
D114
FCXZ000180
Z18V
D115
FCDD102700
Z27V/1
D116
FCDD102700
Z27V/1
D117
FCDIDB3000
DB3
D118
FCXZ000082
Z8.2V
D119
FCXZ000082
Z8.2V
D120
FCXZ000056
Z5.6V
D121
FCXDDBAS16
BAS16
D122
FCXDD40070
1N4007
D123
FCXZ000120
Z12V
D124
FCXDDBAS28
BAS28
D125
FCXDDBAS16
BAS16
D126
FCXDDBAS16
BAS16
D127
FCXDD40070
1N4007
D128
FCXZ000100
Z10V
D129
FCXDDBAS16
BAS16
D130
FCXDDBAS16
BAS16
D131
FCXDDBAS28
BAS28
D132
FCXZ000075
Z7.5V
D133
FCXDDBAS28
BAS28
D134
FCXZ000039
Z3.9V
D135
FCXZ000039
Z3.9V
D136
FCLEDSMD20
TLMH3101
D137
FCLEDSMD20
TLMH3101
D138
40-0113-0105 EP14-02 MPA4-400.xls 2 of 10

PARTS LIST: PRINTED CIRCUIT 11.0956.03.01
Code
Description
Reference
FCDD041200
Z12
D139
FCDD041200
Z12
D140
FCDD041200
Z12
D141
FCDD041200
Z12
D142
FCDD041200
Z12
D143
FCDD041200
Z12
D144
FCXZ000180
Z18V
D145
FCXZ000180
Z18V
D146
FCDD102700
Z27V/1
D147
FCDD102700
Z27V/1
D148
FCDIDB3000
DB3
D149
FCXZ000082
Z8.2V
D150
FCXZ000082
Z8.2V
D151
FCXZ000056
Z5.6V
D152
FCXDD40070
1N4007
D153
FCXZ000120
Z12V
D154
FCXDDBAS28
BAS28
D155
FCXDDBAS16
BAS16
D156
FCXDDBAS16
BAS16
D157
FCFUS50350
F8A
F101
FCFUS50350
F8A
F102
FCFUS50350
F8A
F103
FCFUS50350
F8A
F104
FCFER43220
Ferrite
FB101
FCFER43220
Ferrite
FB102
FCFER43220
Ferrite
FB103
FCFER43220
Ferrite
FB104
FCFER43220
Ferrite
FB105
FCFER43220
Ferrite
FB106
FCFER43220
Ferrite
FB107
FCFER43220
Ferrite
FB108
FCFER43220
Ferrite
FB109
FCFER43220
Ferrite
FB110
FCFER43220
Ferrite
FB111
FCFER43220
Ferrite
FB112
FCMECT0220
Heatsink f/ TO220
HS101
FCMECT0220
Heatsink f/ TO220
HS102
FCMECT0220
Heatsink f/ TO220
HS103
FCMECT0220
Heatsink f/ TO220
HS104
FCMECT0220
Heatsink f/ TO220
HS105
FCMECT0220
Heatsink f/ TO220
HS106
FCMECT0220
Heatsink f/ TO220
HS107
FCRAD13850
Heatsink f/ Power Module
HS108
FCOPTVTL50
VTL 5C8
IC101
FCIC071010
TL071
IC102
FCIC553410
NE5534A
IC103
FCIC431010
LM431AC
IC104
FCIC350000
LM35DZ
IC105
FCIC072010
TL072
IC106
FCREG78050
7805
IC107
FCIC409301
HEF4093B
IC108
FCOPTVTL50
VTL 5C8
IC109
FCIC071010
TL071
IC110
FCIC553410
NE5534A
IC111
FCIC409301
HEF4093B
IC112
FCMICTO126
Insulant TO126
IN101
40-0113-0105 EP14-02 MPA4-400.xls 3 of 10

PARTS LIST: PRINTED CIRCUIT 11.0956.03.01
Code
Description
Reference
FCMICTO126
Insulant TO126
IN102
FCMICTO126
Insulant TO126
IN103
FCMICTO126
Insulant TO126
IN104
FCMICTO126
Insulant TO126
IN105
FCMICTO126
Insulant TO126
IN106
FCMICTO126
Insulant TO126
IN107
FCTIRKON00
Insulating polymer
IN108
FCTIRKON00
Insulating polymer
IN109
FCMICTO126
Insulant TO126
IN112
FCCTM00040
B4B-EH-A
J101
FCCTM00030
B3B-EH-A
J102
FCTERM0100
Jumper Pin
J103
FCTERM0100
Jumper Pin
J104
FCTERM0100
Jumper Pin
J105
FCTERM0100
Jumper Pin
J106
FCTERM0100
Jumper Pin
J107
FCTERM0100
Jumper Pin
J108
FCCTM00030
B3B-EH-A
J109
FCCTM00020
B2B-EH-A
J110
FCCTM00040
B4B-EH-A
J111
FCTERM0100
Jumper Pin
J112
FCTERM0100
Jumper Pin
J113
FCTERM0100
Jumper Pin
J114
FCTERM0100
Jumper Pin
J115
FCTERM0100
Jumper Pin
J116
FCTERM0100
Jumper Pin
J117
FCREL00300
TQ2-12V
K101
FCREL00300
TQ2-12V
K102
FCIND00100
1uH
L101
FCIND00100
1uH
L102
FCMJ000100
Jumper
MJ101
FCMJ000100
Jumper
MJ102
FCMJ000100
Jumper
MJ103
FCMJ000100
Jumper
MJ104
FCMJ000100
Jumper
MJ105
FCMJ000100
Jumper
MJ106
FCPINZAM00
Clamp WD. 00.2636
MP101
FCPINZAM00
Clamp WD. 00.2636
MP102
FCTUE00300
Nut M3
NV101
FCTUE00300
Nut M3
NV102
FCTUE00300
Nut M3
NV103
FCTUE00300
Nut M3
NV104
FCTUE00300
Nut M3
NV105
FCTUE00300
Nut M3
NV106
FCPORF3150
3/15P
PF101
FCPORF3150
3/15P
PF102
FCPORF3150
3/15P
PF103
FCPORF3150
3/15P
PF104
FCTR437000
BD437
Q101
FCTR437000
BD437
Q102
FCTR471000
BF471
Q103
FCTR472000
BF472
Q104
FCTR340000
MJE340
Q105
FCTR350000
MJE350
Q106
FCTR340000
MJE340
Q107
FCTR350000
MJE350
Q108
40-0113-0105 EP14-02 MPA4-400.xls 4 of 10

PARTS LIST: PRINTED CIRCUIT 11.0956.03.01
Code
Description
Reference
FCTR243000
IRFP9240
Q109
FCTR240000
IRFP240
Q110
FCTR243000
IRFP9240
Q111
FCTR240000
IRFP240
Q112
FCXTT08570
BC857B
Q113
FCXTT08470
BC847B
Q114
FCXTT08570
BC857B
Q115
FCXTT08470
BC847B
Q116
FCTR240000
IRFP240
Q117
FCTR243000
IRFP9240
Q118
FCXTT08570
BC857B
Q119
FCXTT08470
BC847B
Q120
FCTI246000
BTB24600B
Q121
FCXTT08570
BC857B
Q122
FCXTT08470
BC847B
Q123
FCTR254010
2N5401
Q124
FCXTT08470
BC847B
Q125
FCXTT08170
BC817/25
Q126
FCTR437000
BD437
Q127
FCTR437000
BD437
Q128
FCTR471000
BF471
Q129
FCTR472000
BF472
Q130
FCTR340000
MJE340
Q131
FCTR350000
MJE350
Q132
FCTR340000
MJE340
Q133
FCTR350000
MJE350
Q134
FCTR243000
IRFP9240
Q135
FCTR240000
IRFP240
Q136
FCTR243000
IRFP9240
Q137
FCTR240000
IRFP240
Q138
FCXTT08570
BC857B
Q139
FCXTT08470
BC847B
Q140
FCXTT08570
BC857B
Q141
FCXTT08470
BC847B
Q142
FCTR240000
IRFP240
Q143
FCTR243000
IRFP9240
Q144
FCXTT08570
BC857B
Q145
FCXTT08470
BC847B
Q146
FCTI246000
BTB24600B
Q147
FCXTT08570
BC857B
Q148
FCXTT08470
BC847B
Q149
FCTR254010
2N5401
Q150
FCXTT08470
BC847B
Q151
FCXTT08170
BC817/25
Q152
FCXR561000
1M
R101
FCXR542150
21k5
R102
FCXR542150
21k5
R103
FCXR542150
21k5
R104
FCXR551000
100k0
R105
FCXR531000
1k0
R106
FCXR531000
1k0
R107
FCXR543480
34k8
R108
FCXR543480
34k8
R109
FCXR531960
1k96
R110
FCXR535620
5k62
R111
FCXR571000
10M
R112
40-0113-0105 EP14-02 MPA4-400.xls 5 of 10

PARTS LIST: PRINTED CIRCUIT 11.0956.03.01
Code
Description
Reference
FCXR531210
1k21
R113
FCXR531210
1k21
R114
FCXR525110
511
R115
FCXR521780
178
R116
FCXR525110
511
R117
FCXR521780
178
R118
FCXR515620
56.2
R119
FCXR531470
1k47
R120
FCXR531470
1k47
R121
FCXR515620
56.2
R122
FCXR526810
681
R123
FCXR531470
1k47
R124
FCRJG44700
4k7
R125
FCXR526810
681
R126
FCXR511000
10.0
R127
FCXR515620
56.2
R128
FCXR523160
316
R129
FCXR515620
56.2
R130
FCXR511000
10.0
R131
FCXR523160
316
R132
FCRF426800
NF68/1
R133
FCRF426800
NF68/1
R134
FCRF232200
NF220/ 1/2
R135
FCRF232200
NF220/ 1/2
R136
FCRF232200
NF220/ 1/2
R137
FCRF232200
NF220/ 1/2
R138
FCRY000100
W0.22/5
R139
FCRY000100
W0.22/5
R140
FCRY000100
W0.22/5
R141
FCRY000100
W0.22/5
R142
FCXR542610
26k1
R143
FCXR542370
23k7
R144
FCRF232200
NF220/ 1/2
R145
FCRF232200
NF220/ 1/2
R146
FCXR525620
562
R147
FCXR525620
562
R148
FCXR524640
464
R149
FCXR524640
464
R150
FCXR543480
34k8
R151
FCXR543480
34k8
R152
FCRY000100
W0.22/5
R153
FCRY000100
W0.22/5
R154
FCXR536810
6k81
R155
FCXR543480
34k8
R156
FCXR543480
34k8
R157
FCXR536810
6k81
R158
FCXR543480
34k8
R159
FCXR543480
34k8
R160
FCXR544640
46k4
R161
FCXR521000
100.0
R162
FCXR521000
100.0
R163
FCXR541330
13k3
R164
FCXR541330
13k3
R165
FCXR521000
100.0
R166
FCXR531000
1k0
R167
FCRY000250
6.8/5W
R168
40-0113-0105 EP14-02 MPA4-400.xls 6 of 10