Ecler DPA2500T User manual

DPA2500T / DPA4000T
SERVICE MANUAL

SERVICE MANUAL DPA2500T DPA4000T
INDEX
-BLOCK DIAGRAM
-FUNCTIONING DESCRIPTION
-SCHEMATICS
-COMPONENTS LOCATION SCHEMA
-TESTING AND QUALITY CONTROL
-TECHNICAL CHARACTERISTICS
-WIRING DIAGRAM
-CONFIGURATION DIAGRAM
-MECHANICAL DIAGRAM
-PACKING DIAGRAM

52-0031-0100 EP04-05-05 DPA2500T DPA4000T Anglès.doc 1 of 2
POWER MODULE.
Due to the high power level required on the output load, the amplifier final stage's structure differs from the design
used until now. This is due to the breakdown voltage limit on P-channel MosFET's, with is 200V. This final stage is
formed by several shunted MosFET's, where those of the positive branch are common-drain configured, and the
negative branch are mounted in common-source configuration.
The system's controlling device is a NE5534-type operational amplifier, with is internally compensated in order to
obtain gain levels equal or higher than three. The amplifier's feedback is given by a resistor and a capacitor
associated to the operational amplifier's non inverting input.
Transistors BF471 and BF472 are common-base configured, forming a current supply structure. This specific
transistor type is used because of the higher Vce voltage level required by this design. They perform
simultaneously two functions: they polarize the MosFET's gate-source junctions, keeping them on the conducting
edge, and they transfer the OpAmp's output voltage variations referred to signal ground.
The signal variations normally reflected by Q107 and referred to the positive power supply, are now needed to be
floating variations, and referred to the outputs. This function is done by Q109-110 (BF472), with are mounted
forming a Wilson-type mirror current supply. This mirror current supply transfers all of the current variations
detected while descending through Q109's collector, to similar variations on Q110's collector also downward
current. Resistors R167 and R174 are used to balance the current mirror, in order to avoid the use of transistors
with forcibly the same beta value. C138 and C141 suppress their resistance when high frequency signal is
processed. Diodes D126 and D127 avoid the transistors to get saturated, and R171 eliminates the loads on
BF472's bases (Baker Circuit).
The system requires about 12Vdc additional voltage upon the usual Vcc level, this allows a correct saturation and a
symmetric clipping at the higher MosFET's.
The correct polarization current value is adjusted by a 4K7 potentiometer connected to the BF transistor's emitter.
This adds an additional current to the current source output on the BF transistor's loading resistors.
In order to maintain the appropriate stand-by current level against varying temperature conditions, BD437-type
transistors are used. As they have a particular temperature-depending base-emitter voltage curve, this voltage is
used to keep a correct voltage reference for the current supply. As the temperature rises, the reference voltage
level decreases, the gate-source voltage also decreases and, finally, the bias current also decreases.
Transistors Q111 and Q112, and their corresponding twins at the lower branch, form a current-buffering circuit with
allows a fast charge and discharge of the power MosFET's gates.
The Zobel circuit, a resistance-capacitance-inductance formed network associated to the amplifier's output, tries to
keep the amplifier's output load impedance constant no matter with load value is connected to the output, or with
frequency is processed, in order to avoid phase shifts on the feedback signal.
To avoid the presence of DC voltage on the output, a diac-triac based system is used, with shorts the output to
signal ground in case the DC level reaches the diac's triggering value. To avoid this to happen when processing
correct signal (sine waveform, music...), the diac obtains its reference level from a filtering network formed by a
100K resistor and a 1µF capacitor.
The protections circuitry overhauls the MosFET's power consumption. Basically, this circuitry consists of two
important sections: MosFET's Id current monitoring, and MosFET's Vds value detection.
author: J. Colomines date: 051006 project:
EP04/05-05
product:
DPA2500T/4000T
E
C
LER approved:
num: 52..0031 version: 01.00
title:
FUNCTIONING DESCRIPTION

52-0031-0100 EP04-05-05 DPA2500T DPA4000T Anglès.doc 2 of 2
When the MosFET's Id level rises above a certain level, transistor Q119 (controlling transistor) conducts and
decreases the BF transistor's loading resistance, thus reducing also their gate-source voltage and, finally, lowering
the Id current value. This system is helped by a delayed performance, due to the associated circuitry to Q145 and
C174. This capacitor starts to charge when a current level above the allowed value is detected, and the protection
starts. The greater is the capacitor's charge level, the higher is also the voltage applied to Q119 controlling
transistor's base, increasing its conduction and, consequently, reducing the gate-source voltage and thus the Id
current value. This system uses a feedback network. The delay used is necessary to avoid clipping the processed
signal's dynamic range, with should result in the typical clipping noise. In the negative branch, the protection
circuitry is associated to control transistor Q120.
In case the overcurrent is not occasional, and persists, after a period of time between 4 and 10 seconds
(determined by R142 and C124), the system switches back to Stand-by mode, due to a system-reset. This is done
by an optocoupler (IC113) associated to the negative branch protection circuitry. When protections get activated,
IC113 gradually charges C124 until a 40106-type Schmidt trigger gate switches over. If the problem persists, this
cycle is repeated.
STANDBY CIRCUITRY. This circuit maintains the Output shutdown relay closed for about 10 seconds, and thus
annulated any current through the MosFET's during this period, just until the whole system's power supply voltage
reaches its stable level. By this system, we avoid to hear through the loudspeakers any possible annoying noise
proceeding from the system's start-up.
This delay time is achieved by using a RC cell, where R135=287K and C119=47µF/50V. As this cell charges, its
voltage increases until reaching the 40106-type Schmidt trigger (IC108) switching value; at this point, the relay
opens and the amplifier starts to function normally.
The discharge or reset of capacitor C119=47µF can be done by cutting off the power supply, or by triggering the
Thermal or other protections. During a short period of time, BC817-type transistor Q102 acts like a switch, shunting
two 75Ωresistors to C119.
Moreover, the amplifier includes some other additional features, like:
- Volume control by a VCA system.
- An ANTICLIP system.
- A Temperature control system.
THE ANTICLIP SYSTEM. When the amplifier reaches clipping levels, the operational amplifier looses control on
the system's performance and at its output some ±Vcc voltage peaking pulses may appear, proceeding from its
power supply. This peaking pulses are used to be rectified and sent to an optocoupler (IC111), with varies the
system's VCA control voltage as a function of those pulse's amplitude, creating a negative feedback with should
pull back the system into stable functioning area.
The Temperature control system has three main functions:
- Controlling the cooling fan speed, as it is a function of the measured temperature. The fan's operation voltage
range is 7 to 14 Volts.
- Suspending the amplifier's functioning when the temperature exceeds 92ºC
- Reducing the amount of power output, depending on the module's temperature (as it rises above 85ºC) and on
the main power supply's transformer (above 120ºC).
The temperature control system consists on two LM35D-type IC's, with act like a thermal probe; one is placed on
the amplifier's heat sink, and the other is placed into the main power supply transformer's core. Moreover, three
amplifiers, a comparator for the thermal probe and a 7805-type IC to feed the cooling fan are used.
The first amplifier (1/4 IC114) acts on the cooling fan speed control. The second amplifier (1/4 IC114) modifies the
VCA gain control, in order to reduce the system's gain if the temperature rises above 85ºC. The third amplifier (1/4
IC114) modifies the VCA gain control, in order to reduce the system's gain if the temperature rises above 120ºC.
The comparator (1/4 IC114) is responsible for the output shutdown relay performance, in order to close it as the
temperature reaches 92ºC, and thus cutting of the amplifier's MosFETs bias current. As this happens, the signal
output of the whole unit is cutted off.

PARTS LIST: PRINTED CIRCUIT 11.1034.02.01
Code
Description
Reference
FCCE35022000
22u/100
C101
FCCE35022000
22u/100
C102
FCCDH7147000
C470n/275V X2
C103
FCCDH7147000
C470n/275V X2
C104
FCCDH7147000
C470n/275V X2
C105
FCCDH7147000
C470n/275V X2
C106
FCCCD2225000
C2n2/250V Y1
C107
FCCCD2225000
C2n2/250V Y1
C108
FCCCD2225000
C2n2/250V Y1
C109
FCCCD2225000
C2n2/250V Y1
C110
FCPERL255000
Cer. Bead
CB101
FCPERL255000
Cer. Bead
CB102
FCPERL255000
Cer. Bead
CB103
FCPERL255000
Cer. Bead
CB104
FCPERL255000
Cer. Bead
CB105
FCPERL255000
Cer. Bead
CB106
FCPERL255000
Cer. Bead
CB107
FCPERL255000
Cer. Bead
CB108
FCPERL255000
Cer. Bead
CB109
FCPERL255000
Cer. Bead
CB110
FCPERL255000
Cer. Bead
CB111
FCPERL255000
Cer. Bead
CB112
FCCI01034000
Printed Board 11.1034.02
CI101
FCDD14007000
1N4007
D101
FCDD14007000
1N4007
D102
FCDD14007000
1N4007
D103
FCDD14007000
1N4007
D104
FCDD14007000
1N4007
D105
FCDD14007000
1N4007
D106
FCDD14007000
1N4007
D107
FCDD14007000
1N4007
D108
FCFUS8040000
16A Temp.
F101
FCFUS8040000
16A Temp.
F102
FCCTAMP06000
6P AMP MALE SOC
J101
FCCTAMP06000
6P AMP MALE SOC
J102
FCCTAMP06000
6P AMP MALE SOC
J103
FCCTAMP06000
6P AMP MALE SOC
J104
FCTERMF63000
Faston 6.3mm
J106
FCTERMF63000
Faston 6.3mm
J107
FCREL1060000
Relay 60V 6000
K101
FCREL1060000
Relay 60V 6000
K102
FCBB2X350000
2x1.5mH
L101
FCBB2X350000
2x1.5mH
L102
FCPORF020000
Fuse clip
PF101
FCPORF020000
Fuse clip
PF102
FCPORF020000
Fuse clip
PF103
FCPORF020000
Fuse clip
PF104
FCRC54560000
5k6/2
R101
FCRC54560000
5k6/2
R102
FCNTC0030000
NTC10
R103
FCNTC0030000
NTC10
R104
FCVDR0275000
VDR275V
RV101
FCVDR0275000
VDR275V
RV102
FCTERMF28000
Faston 2.8mm
TS101
FC2H13620000
1136.02.00
WI104
FC2H13620000
1136.02.00
WI105
40-0160-0100 EP05-05 DPA4000T.xls 1 of 2

PARTS LIST: PRINTED CIRCUIT 11.1034.02.01
Code
Description
Reference
FC2H13720000
1137.02.00
WI106
FC2H13720000
1137.02.00
WI107
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PARTS LIST: PRINTED CIRCUIT 11.1036.02.01
Code
Description
Reference
FCCE36022000
2200u/200
C101
FCCE36022000
2200u/200
C102
FCCE36022000
2200u/200
C103
FCCE36022000
2200u/200
C104
FCCE36022000
2200u/200
C105
FCCE36022000
2200u/200
C106
FCCE36022000
2200u/200
C107
FCCE36022000
2200u/200
C108
FCCE36022000
2200u/200
C109
FCCE36022000
2200u/200
C110
FCCE36022000
2200u/200
C111
FCCE36022000
2200u/200
C112
FCCE36022000
2200u/200
C113
FCCE36022000
2200u/200
C114
FCCE36022000
2200u/200
C115
FCCE36022000
2200u/200
C116
FCCE36022000
2200u/200
C117
FCCE36022000
2200u/200
C118
FCCE36022000
2200u/200
C119
FCCE36022000
2200u/200
C120
FCCI01036000
Printed Board 11.1036.02
CI102
FCTERM100000
Faston 6.3mm
J101
FCTERM100000
Faston 6.3mm
J102
FCTERM100000
Faston 6.3mm
J103
FCTERM100000
Faston 6.3mm
J104
FCRP55330000
33k/2 PR02
R101
FCRP55330000
33k/2 PR02
R102
FCRP55330000
33k/2 PR02
R103
FCRP55330000
33k/2 PR02
R104
FC0H08535000
1085.03.50
WI101
FC0H07125000
1071.02.50
WI102
FC0H08550000
1085.05.00
WI103
FC0H07150000
1071.05.00
WI104
FC0C05128000
1051.02.80
WI107
FC0C05128000
1051.02.80
WI108
FC0C05135000
1051.03.50
WI113
FC0C05135000
1051.03.50
WI114
FC0H13800000
1138.00.00
WI117
FC0H03935000
1039.03.50
WI118
FC0H03935000
1039.03.50
WI119
FC0H03935000
1039.03.50
WI120
FC0H13800000
1138.00.00
WI121
FC0H03935000
1039.03.50
WI122
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