Crown Macro-Tech 5002VZ Manuel de service Page 23
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- Table des matières
- MARQUE LIVRES
Noté. / 5. Basé sur avis des utilisateurs
Circuit Theory 4-9
130446-1 Rev. A
MA-5002VZ Service Manual
©2000 Crown International, Inc.
signal information. An error signal (spike) is produced
any time the shape of the output waveform differs from
the output of the Variable Gain Stage and LOI by more
than 0.05%. This error signal drives the error signal (ES)
input to the PIP connector, the error signal sense test
point, and the compression control circuit.
4.5.4 Compressor
The compression circuitry senses error signal and BGS
level. If the BGS overloads, or an error signal is present,
the compression control circuit (U101) produces a com-
pression drive pulse. A switch on the rear panel selects
the speed of the integrator circuit to follow. In the off
position, the error driven compression is disabled, but
the input overload compression remains on (in fast
speed) to protect the front end. The compression drive
pulse also drives the IOC Integrator (U102). The IOC
integrator not only tells the IOC indicator circuit when to
turn on, but ensures that the indicator will remain on
long enough to be visible to the human eye.
The compression integrator (U102, Q100) sets com-
pression speed and produces an output pulse which
controls attack and decay times. An optic device (U103)
provides a resistive shunt to the input audio according
to the degree of compression required and the dura-
tion of that compression. The amplifier input impedance
is not affected by compressor operation.
4.5.5 Loudspeaker Offset Integration
LOI (U104A/B) senses amplifier feedback and prevents
dynamic DC offset. It operates essentially as a dual fil-
ter system with band pass from about 35 Hz to about
50 kHz. The upper roll-off has a second order Bessel
response while the lower roll-off has a third order
Butterworth response.
4.5.6 Voltage Translator and LVA Stages
The Voltage Translator stages (Q104, Q104) channel
the signal to the Last Voltage Amplifiers (LVAs, located
on the output modules), depending on the signal polar-
ity, from the error amp U105. The ±LVAs, with their push-
pull effect through the High Side bias servo devices,
drive the fully complementary output stage. For more
information on the LVAs, refer to Section 4.2.
U106 and U107 bring in feedback information and pro-
tection muting to the Voltage Translator stages. The feed-
back controls gain from the Voltage Translators to the
output jacks. The protection inputs (±LH) pull off feed
to the Voltage Translators in proportion to ODEP limit-
ing, and completely shut down the feed in the event of
power-down or a Fault.
4.5.7 Inverting Stages
Overall, the amplifier is non-inverting. Four stages within
the amplifier, however, do invert the audio signal for a
net non-inversion. The individual stages are: the BGS,
which inverts the audio; the Variable Gain Stage, which
inverts it back; the input side of U106 and U107 (which
drives the Voltage Translators) re-inverts the audio (the
Voltage Translators are a common-base configuration
for high voltage gain); and finally, the LVAs invert the
audio for the last time for a net non-inversion through
the amplifier.
4.6 Protection Systems
The MA-5002VZ has several protection mechanisms to
limit drive or shutdown the amplifier completely in the
event of a fault of almost any kind. Mechanisms include:
ODEP (covered in depth in Section 4.4), current limit
(covered in Section 4.2.2), over-voltage (on AC mains),
DC/LFI, common mode output current, output thermal,
transformer thermal, FET thermal, loss of AC mains,
compression (covered in Section 4.5.4), LOI (covered
in Section 4.5.5), and slew rate limit (covered in Section
4.2.2). After any non-latching fault which has shut down
the amplifier clears, the amplifier will automatically power
back up via soft-start. Because the fans within the MA-
5002VZ cool the amplifier (under normal conditions) to
prevent thermal shutdowns and ODEP limiting, the fan
control circuit is also covered in this section.
Refer to Figures 4.6, 4.7, and 4.8. Figure 4.6 shows soft-
start and fan control. Figure 4.7 shows the soft-start con-
trol signals. Figure 4.8 shows the over-all protection
scheme of the MA-5002VZ. Each augments the others,
and explode the basic block diagram of the unit (Fig-
ure 4.9).
4.6.1 Soft-start
Soft-start circuitry controls the rate at which power is
initially applied to the primary of the toroid transformers
for the high-voltage power supplies. For ease of expla-
nation, assume the amplifier is operating properly and
is just being turned on from the front panel power switch.
Before the power switch push-button is depressed, the
input to the low voltage supply is open. The high volt-
age supply is isolated via input relay K700 and triac
Q701 (which is in parallel with K700).
Several things occur immediately at turn-on. First, the
low voltage supply powers up and produces its main
unregulated ±24VDC and regulated ±15VDC. It also
immediately produces pulsed DC via full-wave rectifier
D709/D714.
- SERVICE MANUAL 1
- Macro-Tech® 1
- Revision History 3
- Table of Contents 5
- 1 Introduction 7
- 1-2 Introduction 8
- 2 Specifications 9
- ±10 millivolts 10
- 2-4 Specifications 12
- 3 Voltage Conversion 13
- INSTRUCTIONS 13
- 3-2 Voltage Conversion 14
- 4 Circuit Theory 15
- 4-2 Circuit Theory 16
- 4.2.2 Output Stage Circuitry 17
- 4.3 VZ Power Supply 18
- 4.3.2 VZ Supply Circuitry 19
- 4.4 ODEP Theory 20
- On Main ModuleOff Main 21
- 4.5 Front End Theory 22
- 4.6 Protection Systems 23
- 4-10 Circuit Theory 24
- 4.6.2 Over-voltage 25
- 4.6.3 DC/LF 25
- 4.6.5 Output Thermal 26
- 4.6.6 Transformer Thermal 26
- 4.6.7 FET Thermal 26
- 4.7 Display 27
- 4.8 Mono Modes 27
- 4.8.2 Parallel Mono 28
- 5 Maintenance 29
- 5.3.2 LED Checks 30
- Maintenance 5-3 31
- 5.4 Test Procedures 32
- 5-6 Maintenance 34
- Maintenance 5-7 35
- Maintenance 5-9 37
- 5-10 Maintenance 38
- Figure 5.3 10-kHz Square Wave 38
- Maintenance 5-11 39
- ENABLECH2 40
- 5-14 Maintenance 42
- 6 Parts 43
- 6-2 Parts 44
- 7 Exploded View Parts 45
- 7-2 Exploded View Parts 46
- 7.1 Main Chassis Assembly 47
- 7-4 Exploded View Parts 48
- 7.2 Front Chassis Assembly 49
- 7-6 Exploded View Parts 50
- 7.3 Middle Chassis Assembly 51
- 7-8 Exploded View Parts 52
- 7.4 Rear Chassis Assembly 53
- 7-10 Exploded View Parts 54
- Exploded View Parts 7-11 55
- 7-12 Exploded View Parts 56
- 7.6 Transformer Assembly 57
- 7-14 Exploded View Parts 58
- Exploded View Parts 7-15 59
- 7-16 Exploded View Parts 60
- Exploded View Parts 7-17 61
- 7-18 Exploded View Parts 62
- Exploded View Parts 7-19 63
- 7-20 Exploded View Parts 64
- Exploded View Parts 7-21 65
- 7-22 Exploded View Parts 66
- Figure 7.12 Output Assembly 66
- 7.12 Output Assembly 67
- 7-24 Exploded View Parts 68
- Exploded View Parts 7-25 69
- 7-26 Exploded View Parts 70
- Interconnect Cables 71
- 7-28 Exploded View Parts 72
- 8 Module and Schematic 73
- Information 73
- 9 Module Parts 75
- 9-2 Module Parts 76
- Module Parts 9-3 77
- 9-4 Module Parts 78
- Module Parts 9-5 79
- 9-6 Module Parts 80
- Module Parts 9-7 81
- 9-8 Module Parts 82
- Module Parts 9-9 83
- 9-10 Module Parts 84
- Module Parts 9-11 85
- 9-12 Module Parts 86
- Module Parts 9-13 87
- 9-14 Module Parts 88
- Module Parts 9-15 89
- 9-16 Module Parts 90
- Module Parts 9-17 91
- 9-18 Module Parts 92
- Module Parts 9-19 93
- 9-20 Module Parts 94
- Module Parts 9-21 95
- 9-22 Module Parts 96
- Module Parts 9-23 97
- 9-24 Module Parts 98
- Module Parts 9-25 99
- MA-5002VZ Service Manual 100
- 9-26 Module Parts 100
- 130446-1 Rev. A 100
- Module Parts 9-27 101
- 9-28 Module Parts 102
- (Component Side) 103
- 125903-4 PWA Component Map 103
- 9-30 Module Parts 104
- Module Parts 9-31 105
- 9-32 Module Parts 106
- Module Parts 9-33 107
- 9-34 Module Parts 108
- Module Parts 9-35 109
- 9-36 Module Parts 110
- Module Parts 9-37 111
- 9-38 Module Parts 112
- 127488-2 PWA Component Map 113
- 9-40 Module Parts 114
- Module Parts 9-41 115
- 9-42 Module Parts 116
- Module Parts 9-43 117
- 9-44 Module Parts 118
- Module Parts 9-45 119
- 9-46 Module Parts 120
- Module Parts 9-47 121
- 9-48 Module Parts 122
- Q42929-2 PWA Component Map 123
- 9-50 Module Parts 124
- Q42934-2 Negative Emitter PWA 125
- 9-52 Module Parts 126
- Q42935-9 Positive Emitter PWA 127
- 9-54 Module Parts 128
- Module Parts 9-55 129
- 9-56 Module Parts 130
- Module Parts 9-57 131
- 9-58 Module Parts 132
- Module Parts 9-59 133
- 9-60 Module Parts 134
- Module Parts 9-61 135
- 9-62 Module Parts 136
- Module Parts 9-63 137
- 9-64 Module Parts 138
- 10 Schematics 139
- 10-2 Schematics 140
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