Crown k1 Manual Suplementario
K Series Service Manual
Rev A.
Theory 3-1
©1999 Crown International, Inc.
3 Theory
3.0 Overview
This section of the manual explains the general op-
eration of the K Series power amplifier. Topics cov-
ered include Power Supplies, Input Stage, DC Servo,
Sleep Circuit, Error Amp, and Modulator. For Simplic-
ity, the circuit theory will only refer to channel one. It
may be assumed that channel two is identical to chan-
nel one.
eration of the K Series power amplifier. Topics cov-
ered include Power Supplies, Input Stage, DC Servo,
Sleep Circuit, Error Amp, and Modulator. For Simplic-
ity, the circuit theory will only refer to channel one. It
may be assumed that channel two is identical to chan-
nel one.
3.1 Power Supplies
There are numerous power supplies and voltage regu-
lators found within the K Series amplifiers. The main
high energy power supply and the low energy power
supplies are located on the main module.
lators found within the K Series amplifiers. The main
high energy power supply and the low energy power
supplies are located on the main module.
3.1.1 Main Power Supply
The AC line cord is terminated through the fuse to the
AC line filter circuit. C1 is a .22uF capacitor and is
located across the line and neutral leads. C2 and C3
are .0047uF capacitors. C2 is connected from line to
ground and C3 is connected from neutral to ground.
This filter prevents unwanted emissions from contami-
nating the AC power line. The AC power then is routed
to the control board where the power-on relay, soft
start circuit and the AC line voltage configuration cir-
cuits take place.
AC line filter circuit. C1 is a .22uF capacitor and is
located across the line and neutral leads. C2 and C3
are .0047uF capacitors. C2 is connected from line to
ground and C3 is connected from neutral to ground.
This filter prevents unwanted emissions from contami-
nating the AC power line. The AC power then is routed
to the control board where the power-on relay, soft
start circuit and the AC line voltage configuration cir-
cuits take place.
When S1 is closed and power is first applied the relay
K1 is open and current passes through PTC (R1) to
the power transformer primary. The PTC restricts the
amount of inrush current while the transformer is en-
ergizing. When the power supply voltage reaches op-
erating voltage level the relay (K1) closes and by-
passes the PTC resistor. D1 is a diode bridge that is
configured to filter out any DC component on the AC
line. This is included to eliminate the possibility of
“Transformer Buzz” which can occur when a torroidial
transformer is subjected to “dirty” or “noisy” AC power.
K1 is open and current passes through PTC (R1) to
the power transformer primary. The PTC restricts the
amount of inrush current while the transformer is en-
ergizing. When the power supply voltage reaches op-
erating voltage level the relay (K1) closes and by-
passes the PTC resistor. D1 is a diode bridge that is
configured to filter out any DC component on the AC
line. This is included to eliminate the possibility of
“Transformer Buzz” which can occur when a torroidial
transformer is subjected to “dirty” or “noisy” AC power.
The primary wiring configuration for the multi-tap
torroidial power transformer (T1) is accomplished with
a connector plug that contains 9 connections. The
jumpers on the plug determine the amplifiers line volt-
age operating level. Line voltage reconfiguration can
be achieved by inserting the appropriately wired pug
(See Section 4) or by rewiring the existing plug.
torroidial power transformer (T1) is accomplished with
a connector plug that contains 9 connections. The
jumpers on the plug determine the amplifiers line volt-
age operating level. Line voltage reconfiguration can
be achieved by inserting the appropriately wired pug
(See Section 4) or by rewiring the existing plug.
Full wave rectification is achieved by the bridge recti-
fying units D1 and D2 for the high energy supplies
(±Vcc). C5 and C7 filter unwanted AC ripple from the
±Vcc power supplies.
fying units D1 and D2 for the high energy supplies
(±Vcc). C5 and C7 filter unwanted AC ripple from the
±Vcc power supplies.
D3, D4 and R1 detect low energy by sampling the
transformer secondary voltage levels and passing this
on to the Power OK circuit located on the Main mod-
ule (to be covered later).
transformer secondary voltage levels and passing this
on to the Power OK circuit located on the Main mod-
ule (to be covered later).
3.1.2 Low Voltage Power Supplies
On power up the ±Vcc power supplies first initiate.
Once the +Vcc supplies are up to an operational level
they power up the 125KHz oscillator: U9 and the gate
driver: U10. The +Vcc is fed through F1 (3 amp fuse),
L1 and R6. This sends+15V to both U9 and U10. The
output of U10 is amplified by Q2, rectified by D3 and
filtered by C15. The result is a regulated +15VDC. This
+15V feeds U4 (+5V) which starts a 4MHz generator
Y1/U6D (main schematic). The 4MHz output of U6D
is sent to a divide-by chip, U5. U5 generates two out-
puts:
Once the +Vcc supplies are up to an operational level
they power up the 125KHz oscillator: U9 and the gate
driver: U10. The +Vcc is fed through F1 (3 amp fuse),
L1 and R6. This sends+15V to both U9 and U10. The
output of U10 is amplified by Q2, rectified by D3 and
filtered by C15. The result is a regulated +15VDC. This
+15V feeds U4 (+5V) which starts a 4MHz generator
Y1/U6D (main schematic). The 4MHz output of U6D
is sent to a divide-by chip, U5. U5 generates two out-
puts:
1. 500KHz–routed to the triangle generator (see Tri-
angle generator circuit description).
angle generator circuit description).
2. 125KHz–routed back to the low voltage power sup-
ply. This 125KHz signal is fed back in order to drive a
high frequency switch mode power supply. This SMPS
consists of D4, D5, U11A, U11B, Q3 and Q4. U11A
and B drive the 2 FET devices Q3 and Q4. The result-
ing output is a +7V 125KHz signal. The output of this
switch mode power supply is routed in three direc-
tions:
ply. This 125KHz signal is fed back in order to drive a
high frequency switch mode power supply. This SMPS
consists of D4, D5, U11A, U11B, Q3 and Q4. U11A
and B drive the 2 FET devices Q3 and Q4. The result-
ing output is a +7V 125KHz signal. The output of this
switch mode power supply is routed in three direc-
tions:
1. Through C23 this supply is rectified and filtered by
D10, D11, C24, and L5. The output is –13V.
D10, D11, C24, and L5. The output is –13V.
2. Through C22 a 7VAC (15Vp-p) source is routed to
the output stage. In the output stage T1 relays the
power source to the full wave bridge (D01 and D02).
Power Supply filtering is provided by C1, C2, C3 and
C4. This +15V now feeds U03A and U03B (output
stage FET drivers) and a +5V regulator (U01).
the output stage. In the output stage T1 relays the
power source to the full wave bridge (D01 and D02).
Power Supply filtering is provided by C1, C2, C3 and
C4. This +15V now feeds U03A and U03B (output
stage FET drivers) and a +5V regulator (U01).
3. T1 Transformation:
a. Using the primary coil of T1 the signal is filtered by
C26 and L6 to supply +7V. This +7V is used to
feed a number of 5V regulators found on the main
module.
feed a number of 5V regulators found on the main
module.
b. T1 secondary #1: this power supply uses -Vcc as a
reference point. The output is labeled -Vcc+12.
Since the K2 Vcc is ±103V the output of this power
supply is –103V +12V = –98V. D12 and D13 pro-
vide rectification and C27 and C28 provide filtering.
Since the K2 Vcc is ±103V the output of this power
supply is –103V +12V = –98V. D12 and D13 pro-
vide rectification and C27 and C28 provide filtering.