Leisure Craft P-1000 Service manual

Index & Warnings

Technical Specifications, Test Procedures & Adjustments

Block Diagram

Protections, Fuse, Supply, Display, Sockets, Inputs Boards

Driver & Power Boards

Part List, Layout

2
5
6
7
8

SERVICE MANUAL

Schematic Diagrams

CODE : 277320

GENERALMUSIC S.p.A. Sales Division: 47048 S.Giovanni in Marignano (RN) ITALY - Via delle Rose, 12 - tel. [phone] - tlx 550555 GMUSIC I - fax [phone]

Notice

Service must be carried out by qualified personnel only.Any tampering carried out by unqualified personnel during the guarantee

For a correct operation of the instrument, after having switched off, be careful to wait at least 3 seconds before switching on again.
To improve the device's specifications, the schematic diagrams may be subject to change without prior notice.

period will forfeit the right to guarantee.

Schematic Notes

All components marked by this symbol have special safety characteristics, when replacing any of these components use only
manufacturer's specified parts.

The (µ) micro symbol of capacitance value is substituted by U. The (Ω) omega symbol of resistance value is substituted by E.
The electrolytic capacitors are 25Vdc rated voltage unless otherwise specified. All resistors are 1/8W unless otherwise specified.

Soldering point.
Male connector.
Female connector.
M/F faston connector.
Test point.
Flag joined with one or more flags with the same signal name inscribed.

Supply voltage.
Logic supply ground.
Analog supply ground.
Signal ground.
Chassis ground.

Observe precautions when handling

ATTENTION

electrostatic sensitive devices

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TECHNICAL SPECIFICATIONSTECHNICAL SPECIFICATIONS

TECHNICAL SPECIFICATIONS

TECHNICAL SPECIFICATIONSTECHNICAL SPECIFICATIONS

Dimensions: (WxHxD) 483x88x445mm (2U)

Weight: 16Kg

Power Requirements: (230Vac±15% 50/60Hz) 1000VA

(115Vac±15% 50/60Hz) 1000VA

Output Power: (4Ω stereo/parallel) 2x 500Watts

(8Ω stereo/parallel) 2x 350Watts
(8Ω bridge) 1000Watts
(16Ω bridge) 700Watts

Max. Undistorted Out: (4Ω stereo/parallel) 126Vpp

(8Ω stereo/parallel) 149Vpp
(8Ω bridge) 250Vpp

Input Sensitivity: (constant sensitivity) 0.775Vrms (0dB)

(constant gain) 2.25Vrms (+9.2dB)

Input Impedance: (balanced) 30KΩ

(unbalanced) 15KΩ

Voltage Gain: (constant sensitivity) 35±0.5dB

(constant gain) 26±0.5dB

Slew Rate: 25V/µS
Damping Factor: (4Ω stereo/parallel) >400

RemarksRemarks

Remarks

RemarksRemarks

➭ The output coupled transistors TR6-TR11 (MJ15022/B) and TR16-TR22

(MJ15023/B) are factory selected on VBE and V
V
The selection is marked by a red digit (from 0 to B) representative of V
forward voltage categories, these are subdivided in 12 steps of 30mV
each.
Only selected transistors must be used when replacing TR6-TR11 orOnly selected transistors must be used when replacing TR6-TR11 or

Only selected transistors must be used when replacing TR6-TR11 or

Only selected transistors must be used when replacing TR6-TR11 orOnly selected transistors must be used when replacing TR6-TR11 or
TR16-TR22 and every coupled transistors must have the same digit.TR16-TR22 and every coupled transistors must have the same digit.

TR16-TR22 and every coupled transistors must have the same digit.

TR16-TR22 and every coupled transistors must have the same digit.TR16-TR22 and every coupled transistors must have the same digit.

➭ The power supply utilizes a dual bipolar DC rail configuration with low and

high voltages; one positive and one negative low rail (+/-Vcc1) and one
positive and one negative high rail (+/-Vcc2).

Visual CheckVisual Check

Visual Check

Visual CheckVisual Check

➭ Use compressed air to clear dust in the amplifier chassis.
➭ Before proceed to supply the amplifier check visually the internal assem-

bly, if appears an evident damage find the most possible reasons that
cause it.

➭ Check the wiring cables for possible interruptions or shorts.
➭ If the damage has burnt a printed circuit board don’t try to repair it, re-

place with a new one.

Test InstrumentTest Instrument

Test Instrument

Test InstrumentTest Instrument

=11V for NPN and I

(BR)CE0

<6.6mA at V

EC0

BREAKDOWN

=-11V for PNP)

(BR)CE0

(I

EC0<

-6.6mA at

BE

➭ Re-set the Variac at zero voltage, turn off the amplifier and put the fuses

back on its holders.

➭ Connect the oscilloscope probes CH1/2 to the channel outputs, set both

to 20V/div. 200µS/div.

➭ Set up the Variac slowly monitoring the Outputs with the oscilloscope

CH1/2 connected, it should display the sinusoidal input signal amplified
with no distortions, if a distortion occur check the Driver and the Power
Boards as suggested in the ADVICES section.

➭ If the protection trips, turn off the amplifier, wait some minutes and dis-

connect the supplies from the outputs modules (CN1 - CN2 - CN7 - CN8
on POWER boards), continue to check the supplies.

CAUTION: Before re-connecting the output modules to the supplies,CAUTION: Before re-connecting the output modules to the supplies,

➭

CAUTION: Before re-connecting the output modules to the supplies,

CAUTION: Before re-connecting the output modules to the supplies,CAUTION: Before re-connecting the output modules to the supplies,
you must have the capacitors discharged for your safety: connect ayou must have the capacitors discharged for your safety: connect a

you must have the capacitors discharged for your safety: connect a

you must have the capacitors discharged for your safety: connect ayou must have the capacitors discharged for your safety: connect a
100100

ΩΩ

100W resistor across the caps and remove the resistor just 100W resistor across the caps and remove the resistor just

100

Ω

100W resistor across the caps and remove the resistor just

100100

ΩΩ

100W resistor across the caps and remove the resistor just 100W resistor across the caps and remove the resistor just

after they are discharged.after they are discharged.

after they are discharged.

after they are discharged.after they are discharged.

➭ Finally verify the DC supplies on Supply Board:

CN6 (+Vcc2) =+89.5±2Vdc
CN8 (+Vcc1) =+50±1.5Vdc
CN7 (-Vcc1) =-50±1.5Vdc
CN2 (-Vcc2) =-89.5±2Vdc

on Protections Board:

CN2 pin3 =+27±1Vdc
CN3 pin3 =-27±1Vdc
CN1 pin4-5-6 =+13.8±1Vdc
CN1 pin1-2-3 =-13.8±1Vdc

➭ If one or more voltages don’t correspond, check the rectifiers, capacitors

and transformers disconnecting them from circuitry, refer to schematics.

(8Ω stereo/parallel) >800

Frequency Response (-0.2dB) 20Hz÷20KHz

at Full Power: (-3dB) 10Hz÷60KHz

IMD: (SMPTE 60Hz/7KHz 4:1) <0.1%

THD: (THD+N) <0.1%

S/N Ratio: (unweighted) >95dB

Crosstalk: (1KHz) >70dB

TEST PROCEDURES & ADJUSTMENTSTEST PROCEDURES & ADJUSTMENTS

TEST PROCEDURES & ADJUSTMENTS

TEST PROCEDURES & ADJUSTMENTSTEST PROCEDURES & ADJUSTMENTS

PrecautionPrecaution

Precaution

PrecautionPrecaution

➭ To prevent short circuit during any test,

EARTH insulatedEARTH insulated

EARTH insulated, this occurs because some test require to connect its

EARTH insulatedEARTH insulated
probe to the amplifier output, non-compliance may cause damages to
oscilloscope inputs circuitry.

➭ Before removing or installing any modules and connectors,

the amplifier from AC MAINSthe amplifier from AC MAINS

the amplifier from AC MAINS and measure the DC supply voltages

the amplifier from AC MAINSthe amplifier from AC MAINS
across each of the power suppliy capacitors. If your measurement on any

of the caps is greater than 10Vdc, connect a 100Ω 100W resistor across

the applicable caps to discharge them for your safety. Remember to
remove the discharge resistor immediately after discharging caps.
power up the amplifier with the discharge resistor connectedpower up the amplifier with the discharge resistor connected

power up the amplifier with the discharge resistor connected.

power up the amplifier with the discharge resistor connectedpower up the amplifier with the discharge resistor connected

➭ Read these notes entirely before proceeding to any operation. These

notes are not comprehensive of all damages that possibly occur, but
includes some specifically advices, checks and adjustments relative to
this amplifier.

the oscilloscope must bethe oscilloscope must be

the oscilloscope must be

the oscilloscope must bethe oscilloscope must be

disconnectdisconnect

disconnect

disconnectdisconnect

Do notDo not

Do not

Do notDo not

➭ Audio Generator
➭ Dual Trace Oscilloscope
➭ Digital Multimeter
➭ 2Ω 2000W, 4Ω 1000W, 8Ω 1000W, 100Ω 100W resistors
➭ Variac
➭ Temperature Meter

SetupSetup

Setup

SetupSetup

➭ Connect the Variac between the PROTECTION board and the TF1 and

TF2 transformers and set it at zero voltage.

➭ Set the amplifier in STEREO MODE and turn full clockwise the LEVEL

potentiometers.

➭ Connect the audio generator to the channel inputs and set it to 1KHz

775mV

➭ Insert the temperature meter through the IC1 interstice located at centre

of heatsink.

➭ The procedures that follow must be executed subsequently in the order

specified.

Supply CheckSupply Check

Supply Check

Supply CheckSupply Check

➭ Remove the transformer secondary fuses (located on FUSE board), set

the Variac to the nominal mains voltage, check with the Multimeter the
phase opposition between the secondaries of the two transformers (F1­F2,F3-F4), if not, verify the primary connections (T1÷T4 on Protections
Board).

➭ Verify the AC supply voltages: F1-F2=72±2Vac F3-F4=128±3Vac.

(0dB) sinusoidal signal.

RMS

Channels CheckChannels Check

Channels Check

Channels CheckChannels Check

➭ The channel A is facing the front and channel B the rear of the chassis.
➭ These procedures are intended for one channel at a time, repeat these

operation for the other channel.

➭ Verify, with the Multimeter, the insulation between the heatsink and the

transistors collectors.
SETUP:SETUP:

➭

SETUP:

SETUP:SETUP:
Connect the CH1 scope GND clip to CN5 (GND terminal).
Connect the CH1 probe tip to CN6 (AMP output).
Connect the CH2 probe tip to D2 cathode on POWER board.
Set the LEVEL potentiometers full clockwise.
The load resistor is disconnected.

INITIAL TEST:INITIAL TEST:

➭

INITIAL TEST:

INITIAL TEST:INITIAL TEST:
Increase slowly the Variac. The channel output signals must be symmetri­cal respect the GND without visible distortion and oscillation as shown in

Fig.1 Trace A

proceed to check the other channel.
Verify that, when the heatsink temperature is less 50°c, the cooling fan

Fig. 1Fig. 1

Fig. 1

Fig. 1Fig. 1

. If there is a distortion read the section ADVICES and

Trace B (20V/div.)

Trace A (20V/div.)

Trace C (20V/div.)

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voltage must be between 12 and 16V.

HIGH RAIL CHECK:HIGH RAIL CHECK:

➭

HIGH RAIL CHECK:

HIGH RAIL CHECK:HIGH RAIL CHECK:
When the output signal (Positive half-wave) is less than 44Vp the voltage
on D2 cathode must remain constant at 50V, when the output signal
exceeds 44Vp the voltage must follow the output signal with 6V offset
(see

Fig.1 Trace B

D18 anode (see

), to check the negative high rail connect the probe to

Fig.1 Trace C

).

Connect the 4Ω 1000W load on the output and repeat the INITIAL and

HIGH RAIL checks.
Check the signal clipping, it must occur at 130±5Vpp (see

ABC

).

Fig. 2Fig. 2

Fig. 2

Fig. 2Fig. 2

Trace B (20V/div.)

Trace A (20V/div.)

Trace C (20V/div.)

SIGNAL/CLIP SENSOR CHECK:SIGNAL/CLIP SENSOR CHECK:

➭

SIGNAL/CLIP SENSOR CHECK:

SIGNAL/CLIP SENSOR CHECK:SIGNAL/CLIP SENSOR CHECK:

Fig.2 Trace

Set the LEVEL pot to minimum, set the scope timebase at 1V/div. 200µS/

div., then increase the level and check the SIGNAL/CLIP led activity: it
must turn on (green light) when the amplifier output is higher than 5Vpp.
Set the scope at 50V/div. and increase the level, check the led: it must
change from green to red colour when the amplifier output signal clip.
CURRENT AND SHORT CIRCUIT SENSOR CHECK:CURRENT AND SHORT CIRCUIT SENSOR CHECK:

➭

CURRENT AND SHORT CIRCUIT SENSOR CHECK:

CURRENT AND SHORT CIRCUIT SENSOR CHECK:CURRENT AND SHORT CIRCUIT SENSOR CHECK:
Set the CH2 sensitivity to 0.5V/div., connect the scope CH1, GND clip at
CN6 (AMP output) and the probe tip at CN5 (GND terminal), CH2 probe
tip alternatively on TR6, TR11 (NPN) and TR16, TR22 (PNP) emitters.
Set the generator to have approx. 1Vp on the emitters: their difference
must be less than 10% one each other (see

Fig.3 Trace A

). The NPN or
PNP transistors out of tolerance must be replaced with a new selected
pair.

Connect a 2Ω 2000W load. Connect the CH1 probe tip on TR16 emitter

and the CH2 probe tip on TR11 emitter. Increase the input signal, the
output current limiter must keep the emitter voltages (both half channel) at

1.2Vp approx. (see

Fig.3 Trace B

).
Temporarily short the amplifier output: the current limiter must keep the
emitter voltages (both half channel) at 0.7Vp (see

Fig. 3Fig. 3

Fig. 3

Fig. 3Fig. 3

COOLING FAN & PROTECTION CHECK:COOLING FAN & PROTECTION CHECK:

➭

COOLING FAN & PROTECTION CHECK:

COOLING FAN & PROTECTION CHECK:COOLING FAN & PROTECTION CHECK:

Fig.3 Trace C

Trace A (0.5V/div.)

Trace B (0.5V/div.)

Trace C (0.5V/div.)

).

Short circuit pins 11 and 12 of OC1 on Driver board, the fan must run at
max. speed (20÷23Vdc on its tips).
Short circuit pins 9 and 10 of OC1 on the same board, the PROTECT led
must turn on immediately, the fan must run at max. speed. The PROTECT
led of the other channel must also turn on after 2 Sec. and the relay must

disconnect the transformers from the mains.
Remove the short circuit, after 3 Sec. both PROTECT leds must turn off
and the relay must re-connect the transformers to the mains.
Temporarily short the emitter and the collector of TR7 (Driver board) the
PROTECT led must turn on and the relay must disconnect the transform­ers from the mains.
Turn off the amplifier to reset it, wait a minute to let the supply caps
discharged.

OFFSET SENSOR CHECK:OFFSET SENSOR CHECK:

➭

OFFSET SENSOR CHECK:

OFFSET SENSOR CHECK:OFFSET SENSOR CHECK:
Set the Variac to zero voltage output, disconnect the amplifier load and
the supply connection to the Power board (CN1,2,7,8), turn on the ampli­fier, connect temporarily (by means of a suitable conductor wire) CN6 to
+15Vdc, the PROTECT led must turn on immediately; the fan must run at
maximum speed).
Reset the protection turning off the amplifier, turn it on again, connect
temporarily (by means of a suitable conductor wire) CN6 to -15Vdc, the
led PROTECT must turn on again.

SOA ADJUSTMENT:SOA ADJUSTMENT:

➭

SOA ADJUSTMENT:

SOA ADJUSTMENT:SOA ADJUSTMENT:
Set the scope sensitivity at 5V/div. (both channels) and connect the CH1
probe on D12 cathode and the CH2 probe on D11 anode on Driver board,
check the voltage across D12 and D11 zener diodes: it must be

14.8±0.1V; increasing 10dB the generator level this voltage does not
decrease more than 0.5V.

Connect the 4Ω 1000W load, set the scope sensitivity at 2V/div. and

connect the CH1 probe tip at R43 side CN3 and the CH2 probe tip at R36
side CN2. Decrease the signal level until two sinusoid appear on the
scope as shown in

Fig. 4Fig. 4

Fig. 4

Fig. 4Fig. 4

Fig 4 Trace AB

.

Trace A (2V/div.)

Trace C (20V/div.)
(Amplifier Output)

Trace B (2V/div.)

Their max. amplitude must be 5.5Vp (the outer) and 1.5Vp (the inner) as
shown in

Fig 5 Trace A,B

sinusoid must produce spikes on its peaks as shown in

; increasing a bit the generator signal, the inner

Fig 5 Trace A,B

Connect the 2Ω 1000W load, set the scope sensitivity at 1V/div. (both

channels) and connect its probes to the collectors of TR8 (CH1) and
TR11 (CH2) on Driver Board.

Fig. 5Fig. 5

Fig. 5

Fig. 5Fig. 5

Trace A (2V/div.)

Trace C (20V/div.)
(Amplifier Output)

Trace B (2V/div.)

Disconnect the fan; wait until the temperature is 90°C (require some
minutes) then decrease the input to zero.
Adjust the trimmers R20 and R40, until the scope traces go respectively
at -2.2Vdc and +2.3Vdc; turn on the cooling fan and wait until the tem­perature goes down to 80°C; then turn it off.

Reconnect the 4Ω 1000W load, adjust the level for the maximum dis-

placement of the scope tracks toward the centre of the scope screen (­3dB approx.); the SOA control circuit (Protect led light on) will start at
90±2°C.
Reconnect the cooling fan and check with the Multimeter its supply volt­age: it must be 20V or more (max speed).
At 70°C heatsink temperature, short circuit the amplifier output and check
the scope traces: they must displace 1V toward the centre of the screen,

respect to the previous position with 4Ω load.

Remove the short and decrease the input level to zero. The temperature
will decrease: at 65..75°C the speed of the cooling fan must change from
max to min speed. In case of a fan misbehaviour try to replace the D10
zener diode: if speed change at 75°C or more replace with a lower volt­age zener diode, if speed change at 60°C or less replace with a higher
voltage zener diode.

BIAS ADJUSTMENT:BIAS ADJUSTMENT:

➭

BIAS ADJUSTMENT:

BIAS ADJUSTMENT:BIAS ADJUSTMENT:
Connect the Multimeter across

R54 of Power board, when the heatsink
temperature rises at 50°C, turn off the cooling fan and adjust R31 to read
2mV.
Set the scope sensitivity at 1V/div.(CH1), and connect the GND clip to the
amplifier GND (CN5) and the probe tip on the output (CN6). Adjust the
generator level until the sinewave appears at full screen amplitude, No
crossover distortion must be detectable: if necessary re-adjust R31. Re­connect the fan.

BANDWIDTH CHECK:BANDWIDTH CHECK:

➭

BANDWIDTH CHECK:

BANDWIDTH CHECK:BANDWIDTH CHECK:
Sweep the generator frequency from 20Hz to 20KHz, the output level
must have not detectable level changes.

SLEW RATE CHECK:SLEW RATE CHECK:

➭

SLEW RATE CHECK:

SLEW RATE CHECK:SLEW RATE CHECK:
Set the scope sensitivity to 10V/div. 1mS/div. and set the generator to
1KHz square wave mode. Check the output square wave rising and falling

edge slopes: both must be 12V/µS or more.

➭ Disconnect the Variac and re-connect the transformer primaries to the

PROTECTIONS board (be careful to connect the two transformers out of
phase).

Inputs Board CheckInputs Board Check

Inputs Board Check

Inputs Board CheckInputs Board Check

➭ These procedures are intended for one channel at a time, repeat these

operations for the other channel.

.

SETUP:SETUP:

➭

SETUP:

SETUP:SETUP:
Connect the CH1 probe to amplifier input of the channel under test and
set both at 500mV/div. 200mS/div.
Connect the CH2 probe to amplifier output of the channel under test and
set it at 10mV/div. 200mS/div.
Set the audio generator at 1KHz sinus. 775mV

RMS

(0dB).
Set the LEVEL potentiometers full clockwise.
The load resistor is disconnected.

CMRR ADJUSTMENTCMRR ADJUSTMENT

➭

CMRR ADJUSTMENT

CMRR ADJUSTMENTCMRR ADJUSTMENT
Temporarily disconnect pin 3 from pin 1and short the pin 2 (positive input)
and pin 3 (negative input) of XLR input socket.
Adjust the trimmer R10 (channel A) or R21 (channel B) to obtain the
minimum output level.
GAIN ADJUSTMENTGAIN ADJUSTMENT

➭

GAIN ADJUSTMENT

GAIN ADJUSTMENTGAIN ADJUSTMENT
Re-set the input signal at pin 2 (positive input) and pin 3 (negative input)
short with pin 1 (GND) of XLR input socket
Set CH2 scope at 500mV/div. and connect it to the output of INPUTS
board (CN3 pin9 for channel A or CN3 pin7 for channel B).
Set the input SENSITIVITY (SW1) at 2.25Vrms, adjust the trimmer R5

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