Crown MA-3600, MA-3600-VZ, Macro-Tech 3600, Macro-Tech 3600-VZ Service manual

POWER AMPLIFIER

SERVICE MANUAL

Macro-Tech

MA-3600VZ

Some models may be exported under the name Amcron

© 2000 by Crown International, Inc., P.O. Box 1000, Elkhart, Indiana 46515-1000 U.S.A. Telephone: 219-294-8000. Trademark Notice: PIP™, Grounded Bridge™, and SmartAmp™ are trademarks and Amcron®, Crown®, Macro-Tech®, IOC®, ODEP® and IQ System® are

registered trademarks of Crown International, Inc. Other trademarks are the property of their respective owners.

130366-1

11-00

Rev. A

MA-3600VZ Service Manual

The information furnished in this manual does not include all of the details of design, production, or variations of the equipment. Nor does it cover every possible situation which may arise during installation, operation or maintenance. If you need special assistance beyond the scope of this manual, please contact the Crown Technical Support Group.

Mail: P.O. Box 1000 Elkhart IN 46515-1000

Shipping: Plant 2 SW 1718 W. Mishawaka Road Elkhart IN 46517

Phone: (800) 342-6939 / (219) 294-8200

FAX: (219) 294-8301

130366-1 Rev. A

CAUTION

TO PREVENT ELECTRIC SHOCK DO

NOT REMOVE TOP OR BOTTOM COVERS. NO USER SERVICEABLE PARTS INSIDE. REFER SERVICING

TO QUALIFIED SERVICE PERSON-

NEL. DISCONNECT POWER CORD

BEFORE REMOVING REAR INPUT

MODULE TO ACCESS GAIN SWITCH.

WARNING

TO REDUCE THE RISK OF ELECTRIC

SHOCK, DO NOT EXPOSE THIS

EQUIPMENT TO RAIN OR MOISTURE!

AVIS

À PRÉVENIR LE CHOC ÉLECTRIQUE N’ENLEVEZ PAS LES COUVERTURES.

RIEN DES PARTIES UTILES

À L’INTÉRIEUR.

DÉBRANCHER LA BORNE

AVANT D’OUVRIR LA

MODULE EN ARRIÈRE.

The lightning bolt triangle is used to alert the user to the risk of electric shock.

The exclamation point triangle is used to alert the user to important operating or maintenance instructions.

130366-1 Rev. A

MA-3600VZ Service Manual

Revision History

Revision Number

Rev. A

Date

11-2000 Initial Printing

Comments

III

MA-3600VZ Service Manual

130366-1 Rev. A

This page intentionally left blank

130366-1 Rev. A

1 Introduction............................................................................ 1-1

1.1 Introduction...........................................................................................1-1

1.2 The Macro-Tech Series Ampliﬁ ers ........................................................1-1

1.3 Scope....................................................................................................1-1

1.4 Warranty................................................................................................1-1

2 Speciﬁ cations ......................................................................... 2-1

2.1 Performance .........................................................................................2-1

2.2 Power ....................................................................................................2-1

2.3 Controls.................................................................................................2-1

2.4 Indicators ..............................................................................................2-1

2.5 Input/Output..........................................................................................2-2

2.6 Protection..............................................................................................2-2

2.7 Construction..........................................................................................2-2

3 Theory of Operation .................................................................. 3-1

3.1 Overview ...............................................................................................3-1

3.2 Features ................................................................................................3-1

3.3 Front End Operation..............................................................................3-1

3.4 Voltage Ampliﬁ cation ............................................................................3-2

3.5 Grounded Bridge Topology ..................................................................3-2

3.6 Output Device Emulation Protection (ODEP)........................................ 3-4

3.7 VZ Power...............................................................................................3-4

4 Maintenance .......................................................................... 4-1

4.1 Cautions and Warnings........................................................................ 4-1

4.2 General Information ..............................................................................4-1

4.3 Test Procedures ...................................................................................4-1

5 Parts .................................................................................... 5-1

5.1 General Information .............................................................................5-1

5.2 Ordering and Receiving Parts ............................................................ 5-1

5.3 Mechanical Parts ..................................................................................5-1

5.4 Circuit Board Parts..............................................................................5-19

6 Schematic Diagrams................................................................ 6-1

MA-3600VZ Service Manual

This Page Intentionally Left Blank

130366-1 Rev. A

1 Introduction

1.1 Introduction

This manual contains complete service information on the Crown® MA-3600VZ power ampliﬁ er. It is designed to be used in conjunction with the Reference Manual; however, some important information is duplicated in this Service Manual in case the Reference Manual is not readily available.

MA-3600VZ Service Manual

feature balanced inputs with bridged and parallel monophonic capability. Specific features vary depending on model.

1.3 Scope

This Service Manual in intended to apply to all versions of the MA-3600VZ amplifier. The Parts Listings include parts speciﬁ c for the US version and the European version (E17CE). For parts speciﬁ c only to other versions contact the Crown Technical Support Group for help in ﬁ nding part numbers.

NOTE: THE INFORMATION IN THIS MANUAL IS INTENDED FOR USE BY AN EXPERIENCED TECHNICIAN ONLY!

1.2 The Macro-Tech Series Ampliﬁ ers

The Macro-Tech® series is a complete family of amplifiers designed for pro sound reinforcement. Macro-Tech amplifiers are designed to provide enormous levels of pure, undistorted power in a rugged low-profile package, utilizing Crown's patented Grounded Bridge™ output topology. They also employ Crown's patented ODEP® protection circuitry, which keeps the ampliﬁ er working under extreme conditions that would shut down a lesser ampliﬁ er. The MA-3600VZ features Crown's PIP™ (Programmable Input Processor) expansion system. The PIP expansion system makes it easy to tailor the amplifier to a specific application. Providing high power ampliﬁ cation from 20 Hz to 20 kHz with minimum distortion, Macro-Tech series amplifiers

Crown Customer Service

Technical Support Group

Factory Service

Parts Department

1.4 Warranty

Each Reference Manual contains basic policies as related to the customer. In addition, it should be stated that this service documentation is meant to be used only by properly trained personnel. Because most Crown products carry a 3-Year Full Warranty (including round trip shipping within the United States), all warranty service should be referred to the Crown Factory or Authorized Warranty Service Center. See the applicable Reference Manual for warranty details. To ﬁ nd the location of the nearest Authorized Warranty Service Center or to obtain instructions for receiving Crown Factory Service, please contact the Crown Technical Support Group (within North America), or your Crown/Amcron Importer (outside North America). If you are an Authorized Warranty Service Center and have questions regarding the warranty of a product, please contact the Field Service Manager or the Technical Support Group.

Mailing Address: P.O. Box 1000, Elkhart IN 46515

Shipping Address: Plant 2 S. W.

1718 W. Mishawaka Rd., Elkhart IN 46517

Phone: (219) 294-8200

Toll Free: (800) 342-6939

Fax: (219) 294-8301

http://www.crownaudio.com

Introduction 1-1

MA-3600VZ Service Manual

130366-1 Rev. A

Introduction 1-2

Figure 1.1 MA-3600VZ Front and Rear Views

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2 Speciﬁ cations

These speciﬁ cations apply to 120 VAC units in stereo mode with 8 ohm loads and an input sensitivity of 26 dB unless otherwise speciﬁ ed.

120 VAC, 60 Hz Units: These units are equipped with transformers rated for 120 VAC, 60 Hz power.

International Units: These units are equipped with transformers for either 100 VAC, 50/60 Hz, or 230 VAC, 50/60 Hz power.

2.1 Performance

Frequency Response: ±0.1 dB from 20 Hz to 20 kHz at 1 watt.

Phase Response: ±10° from 10 Hz to 20 kHz at 1 watt.

Signal-to-Noise Ratio: Greater than 105 dB below rated

output (20 Hz to 20 kHz, A-weighted); 100 dB below rated output (20 Hz to 20 kHz, no weighting).

Harmonic Distortion (THD): At rated output, less than 0.05% from 20 Hz to 1 kHz increasing linearly to less than 0.1% at 20 kHz.

IM Distortion (IMD): Less than 0.05% from 368 milliwatts to full rated output.

Damping Factor: Greater than 1,000 from 10 Hz to 400 Hz.

Crosstalk: See Figure 2.1.

Slew Rate: Greater than 30 volts per microsecond.

Voltage Gain: (At maximum output) 20:1 ±3% or 26 dB ±0.25

dB at +26 dB sensitivity, and 124.6:1 ±12% or 41.9 dB ±1.0 dB at 0.775 volt sensitivity.

2.2 Power

Output Power:

Note: Maximum average watts per channel (unless in Mono mode) at 1 kHz with 0.1% or less THD.

120 VAC, 60 Hz Units: Stereo mode with both channels driven: 1800 watts into 2 ohms. 1565 watts into 4 ohms. 1120 watts into 8 ohms. Bridge-Mono mode: 3505 watts into 4 ohms. 3140 watts into 8 ohms. Parallel-Mono mode: 3555 watts into 1 ohm. 3190 watts into 2 ohms.

100 VAC International Units:

Stereo mode with both channels driven: 1460 watts into 2 ohms. 1300 watts into 4 ohms. 980 watts into 8 ohms. Bridge-Mono mode: 2835 watts into 4 ohms. 2625 watts into 8 ohms. Parallel-Mono Mode 2820 watts into 1 ohm. 2585 watts into 2 ohms.

MA-3600VZ Service Manual

120 VAC International Units:

Stereo mode with both channels driven: 1490 watts into 2 ohms. 1300 watts into 4 ohms. 985 watts into 8 ohms. Bridge-Mono mode: 2980 watts into 4 ohms. 2600 watts into 8 ohms. Parallel-Mono Mode 2980 watts into 1 ohm. 2600 watts into 2 ohms.

230 VAC International Units:

Stereo mode with both channels driven: 1520 watts into 2 ohms. 1325 watts into 4 ohms. 965 watts into 8 ohms. Bridge-Mono mode: 2800 watts into 4 ohms. 2515 watts into 8 ohms. Parallel-Mono Mode 2910 watts into 1 ohm.

2565 watts into 2 ohms.

Load Impedance: Rated for 16, 8, 4, and 2 ohm use only. Safe with all types of loads, even reactive ones.

AC Power Requirements: 100 VAC, 50/60 Hz; 120 VAC, 50/60 Hz; and 230 VAC, 50/60 Hz units are available. 230 VAC, 50/60 Hz units can be used with 220 and 240 VAC. All versions draw 90 watts or less at idle. 100 and 120 VAC units can draw up to 30 amps of current; 230 VAC units can draw up to 15 amps. Refer to the back panel for your unit’s speciﬁ cations.

2.3 Controls

Enable: A front panel push button used to turn the ampliﬁ er on and off.

Level: A 31-position detented rotary attenuator for each channel located on the front panel used to control the output level.

Stereo/Mono: A three-position back panel switch used to select Stereo, Bridge-Mono or Parallel-Mono operation.

Sensitivity: A three-position switch located inside the PIP compartment used to select one of three input sensitivities for both channels: 0.775 volts or 1.4 volts for standard 1 kHz power or a voltage gain of 26 dB.

Input Ground Lift: A two position back panel switch used to isolate the phone jack signal grounds from the chassis (AC) ground.

Reset: A back panel button for each channel used to reset the corresponding power supply. 100 and 120 VAC units have 15 amp circuit breakers. 230 VAC units have 7.5 amp circuit breakers.

2.4 Indicators

Enable: This amber indicator is on when the ampliﬁ er is switched on to show that the low voltage power supply is operating.

Signal / IOC: Two green indicators ﬂ ash with medium inten- sity in sync with the ampliﬁ er’s outputs to show signal pres-

Speciﬁ cations 2-1

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130366-1 Rev. A

ence. In the unlikely event the output waveform differs from that of the input by 0.05% or more, they ﬂ ash brightly to indi- cate distortion. As sensitive distortion indicators they provide proof of performance. Note: It is normal for the Channel 2 IOC indicator to remain on in Parallel-Mono mode.

ODEP: Each channel has a multifunction LED (light emitting diode) indicator that shows the channel’s energy reserve status. Normally, the LEDs are brightly lit to show that reserve energy is available. An indicator will dim proportionally as the energy reserve for its channel decreases. In the rare event that a channel has no reserve energy, the indicator turns off and ODEP proportionally limits the channel’s output drive level so the ampliﬁ er can continue safe operation even when conditions are severe.

2.5 Input/Output

Input Connector: Balanced ¼-inch phone jacks on chassis and internal PIP connector. (Balanced 3-pin XLR connectors are provided on the P.I.P.-FX which is a standard feature.)

Input Impedance: Nominally 20 k ohms, balanced. Nominally 10 K ohms, unbalanced.

Input Sensitivity: Switchable between 0.775 V (unbalanced) for rated output or a ﬁ xed voltage gain of 26 dB.

Output Connector: Color-coded dual binding posts (banana jacks).

Output Impedance: Less than 10 milliohms in series with less than 2 microhenries.

DC Output Offset: (Shorted input) ±10 millivolts.

Output Signal;

Stereo: Unbalanced, two-channel, Bridge-Mono: Balanced, single-channel. Channel 1 controls

are active; Channel 2 controls are inactive and not removed from operation,

Parallel-Mono: Unbalanced, single-channel. Channel 1

controls are active; Channel 2 controls are inactive but notremoved from operation.

2.7 Construction

Durable black powder coated steel chassis and aluminum front panel with Lexan overlay; specially designed “ﬂ ow- through” ventilation from front to side panels.

Cooling: Forced-air with custom heat diffusers and patented circuitry to promote uniform dissipation.

Dimensions: 19 inch (48.3 cm) standard rack mount (EIA Std. RS-310-B), 3.5 inch (8.9 cm) height, 16 inch (40.6 cm) depth behind mounting surface and 2.5 inches (6.4 cm) in front of mounting surface (see Figure 2.2).

Approximate Weight: Center of gravity is 6 inches (15.2 cm) behind the front mounting surface.

120 VAC, 60 Hz Units: Net weight 55 lbs, 1.5 ounces (25.0 kg); shipping weight

63 lbs, 10 ounces (28.9 kg).

100 VAC International Units:

Net weight 54 lbs, 5 ounces (24.7 kg); shipping weight 63

lbs, 0.5 ounces (28.6 kg). 120 VAC International Units: Net weight 55 lbs, 1.5 ounces (25.0 kg); shipping weight

63 lbs, 10 ounces (28.9 kg). 230 VAC International Units: Net weight 53 lbs, 6 ounces (24.2 kg); shipping weight 61

lbs, 15 ounces (28.1 kg).

2.6 Protection

Macro-Tech ampliﬁ ers are protected against shorted, open or mismatched loads; overloaded power supplies; excessive temperature, chain destruction phenomena, input overload damage and high-frequency blow-ups. They also protect loudspeakers from input/output DC and turn-on/turn-off transients.

If unreasonable operating conditions occur, the patented ODEP circuitry proportionally limits the drive level to protect the output devices, particularly in the case of elevated temperature. Transformer overheating results in a temporary shutdown of the offending channel. When it has cooled to a safe temperature, the transformer automatically resets itself. Controlled slew rate voltage ampliﬁ ers protect against RF burnouts, and input overload protection is provided by current-limiting resistance at the input.

Turn On: The four second turn-on delay prevents dangerous turn-on transients. Turn-on occurs at zero crossing of the AC waveform, so power sequencers are rarely needed with multiple units. Note: The turn-on delay time may be changed. Contact Crown’s Technical Support Group for details.

Circuit Breaker: Circuit breaker current ratings vary based on the AC operating power.

Speciﬁ cations 2-2

100 1 K 10 K 20 K

TEF

FREQUENCY (Hz)

Figure 2.1 Typical Crosstalk

Figure 2.2 Dimensions

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3 Theory of Operation

3.1 Overview

It should be noted that over time Crown makes improvements and changes to their products for various reasons. This manual is up to date as of the time of writing. For additional information regarding these ampliﬁ ers, refer to the applicable Technical Notes provided by Crown for this product.

MA-3600VZ Service Manual

front panel and are of the rotary type. Front panel indicators let the user know the status of the low voltage power supply (enable), an ODEP indicator for each channel which shows the reserve energy status, and a SPI/IOC indicator for each channel which indicates signal output and distortion. In general, the packaging of this model is designed for maximum watt/price/weight/size value with user friendly features.

For additional details refer to the speciﬁ cation section, or to the applicable Owner’s Manual.

This section of the manual explains the general operation of a Macro-Tech 3600VZ power ampliﬁ er. Topics covered include Front End, Grounded Bridge, ODEP, and VZ supply. Due to variations in design from vintage to vintage (and similarities with other Crown products) the theory of operation remains simpliﬁ ed.

3.2 Features

Macro Tech amplifiers utilize numerous Crown innovations including grounded bridge and ODEP technologies. Cooling techniques make use of the what is essentially air conditioner technology. Air ﬂ ows bottom to top, and front to side. Air ﬂ ows a short distance across a wide heatsink. This type of air flow provides significantly better cooling than the “wind tunnel” technology used by many other manufacturers. Output transistors are of the metal can type rather than plastic case. This allows for a signiﬁ cantly higher thermal margin for the given voltage and current ratings. All devices used are tested and graded to ensure maximum reliability. Another electronic technique used is negative feedback. Almost all power ampliﬁ ers utilize negative feedback to control gain and provide stability, but Crown uses multiple nested feedback loops for maximum stability and greatly improved damping. Most Crown ampliﬁ ers have damping in excess of 1000 in the bass frequency range. This feedback, along with our compensation and ultra-low distortion output topology, makes Crown ampliﬁ ers superior.

Features speciﬁ c to the Macro Tech Series’ include two seperate power transformers (one for each channel), a full time full speed fan which also serves as the low voltage transformer, slew rate limiting, and audio muting for delay or protective action. This ampliﬁ er can operate in either a Bridged or Parallel Mono mode as well as dual (stereo). A sensitivity switch allows selection of input voltage required for rated output. Level controls are mounted on the

3.3 Front End Operation

The front end is comprised of three stages: Balanced Gain Stage (BGS), Variable Gain Stage (VGS), and the Error Amp. Figure 3.1 shows a simpliﬁ ed diagram of a typical front end with voltage amplification stages.

3.3.1 Balanced Gain Stage (BGS)

Input to the ampliﬁ er is balanced. The shield may be isolated from chassis ground by an RC network to interrupt ground loops via the Ground Lift Switch. The non-inverting (hot) side of the balanced input is fed to the non-inverting input of the ﬁ rst op-amp stage. The inverting (negative) side of the balanced input is fed to the inverting input of the ﬁ rst op-amp stage. A potentiometer is provided for common mode rejection adjustment. Electrically, the BGS is at unity gain. (From an audio perspective, however, this stage actually provides +6dB gain if a fully balanced signal is placed on its input.) The BGS is a non-inverting stage. It’s output is delivered to the Variable Gain Stage.

3.3.2 Variable Gain Stage (VGS)

From the output of the BGS, the signal goes to the VGS where gain is determined by the position of the Sensitivity Switch, and level is determined by the level control. VGS is an inverting stage with the input being fed to its op-amp stage. Because gain after this stage is ﬁ xed at 26dB (factor of 20), greater ampliﬁ er sensitivity is achieved by controlling the ratio of feedback to input resistance. The Sensitivity Switch sets the input impedance to this stage and varies the gain such that the overall ampliﬁ er gain is 26 dB, or is adjusted appropriately for 0.775V or 1.4V input to attain rated output.

3.3.3 Error Amp

The inverted output from the VGS is fed to the noninverting input of the Error Amp op-amp stage through

Theory of Operation 3-1

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an AC coupling capacitor and input resistor. Ampliﬁ er output is fed back via the negative feedback (NFb) loop resistor. The ratio of feedback resistor to input resistor ﬁ xes gain from the Error Amp input to the output of the amplifier at 26 dB. Diodes prevent overdriving the Error Amp. Because the Error Amp ampliﬁ es the difference between input and output signals, any difference in the two waveforms will produce a near open loop gain condition which in turn results in high peak output voltage. The output of the Error Amp, called the Error Signal (ES) drives the Voltage Translators.

3.4 Voltage Ampliﬁ cation

The Voltage Translator stage separates the output of the Error Amp into balanced positive and negative drive voltages for the Last Voltage Ampliﬁ ers (LVAs), translating the signal from ground referenced ±15V to ±Vcc reference. LVAs provide the main voltage ampliﬁ cation and drive the High Side output stages. Gain from Voltage Translator input to ampliﬁ er output is a factor of 25.2.

3.4.1 Voltage Translators

A voltage divider network splits the Error Signal (ES) into positive and negative drive signals for the balanced voltage translator stage. These offset reference voltages drive the input to the Voltage Translator transistors. A nested NFb loop from the output of the ampliﬁ er mixes with the inverted signal riding on the offset references. This negative feedback ﬁ xes gain at the offset reference points (and the output of the Error Amp) at a factor of -25.2 with respect to the ampliﬁ er output. The Voltage Translators are arranged in a common base conﬁ guration for non-inverting voltage gain with equal gain. They shift the audio from the ±15V reference to VCC reference. Their outputs drive their respective LVA.

Also tied into the Voltage Translator inputs are ODEP limiting transistors and control/protection transistors. The ODEP transistors steal drive as dictated by the ODEP circuitry (discussed later). The control/protection transistors act as switches to totally shunt audio to ground during the turn-on delay, or during a DC/LF or Fault protective action.

3.4.2 Last Voltage Ampliﬁ ers (LVAs)

The Voltage Translator stage channels the signal to the Last Voltage Ampliﬁ ers (LVA’s) in a balanced conﬁ guration. The +LVA and -LVA, with their push- pull effect through the Bias Servo, drive the fully complementary output stage. The LVAs are conﬁ gured as common emitter amplifiers. This configuration provides sufﬁ cient voltage gain and inverts the audio. The polarity inversion is necessary to avoid an overall polarity inversion from input jack to output jack, and it allows the NFb loop to control Error Amp gain by feeding back to its non-inverting input (with its polarity opposite to the output of the VGS). With the added voltage swing provided by the LVAs, the signal then gains current ampliﬁ cation through the Darlington emitter-follower output stage.

3.5 Grounded Bridge Topology

Figure 3.2 is a simpliﬁ ed example of the grounded bridge output topology. It consists of four quadrants of three deep Darlington (composite) emitter-follower stages per channel: one NPN and one PNP on the High Side of the bridge (driving the load), and one NPN and one PNP on the Low Side of the bridge (controlling the ground reference for the rails). The output stages are biased to operate class AB+B for ultra low distortion in the signal zero-crossing region and high efﬁ ciency.

BGS VGS Error

Audio

Inputs

Figure 3.1 Typical Ampliﬁ er Front End and Voltage Ampliﬁ cation Stages.

Theory of Operation 3-2

+15V

Amp

ODEP

Q100

Q103

Voltage Divider

-15V

Q121

Mute

NFb Loo

Voltage

Translators

Q101

Q122

Q102

+VCC

Q105

NPN Outputs (+HS) PNP Outputs (-HS)

Q110

-VCC

LVA’s

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MA-3600VZ Service Manual

3.5.1 High Side (HS)

The High Side (HS) of the bridge operates much like a conventional bipolar push-pull output conﬁ guration. As the input drive voltage becomes more positive, the HS NPN conducts and delivers positive voltage to the load. Eventually the NPN devices reach full conduction and +Vcc is across the load. At this time the HS PNP is biased off. When the drive signal is negative going, the HS PNP conducts to deliver -Vcc to the load and the HS NPN stage is off.

The output of the +LVA drives the base of predriver device. Together, the predriver and driver form the ﬁ rst two parts of the three-deep Darlington and are biased class AB. They provide output drive through the bias resistor, bypassing the output devices, at levels below about 100mW. An RLC network between the predriver and driver provide phase shift compensation and limit driver base current to safe levels. Output devices are biased class B, just below cutoff. At about 100mW output they switch on to conduct high current to the load. Together with predriver and driver, the output device provide an overall class AB+B output.

The negative half of the HS is almost identical to the positive half, except that the devices are PNP. One difference is that the PNP bias resistor is slightly greater in value so that PNP output devices run closer to the cutoff level under static (no signal) conditions. This is because PNP devices require greater drive current.

HS bias is regulated by Q18, the Bias Servo. Q18 is a Vbe multiplier which maintains approximately

3.3V Vce under static conditions. The positive and negative halves of the HS output are in parallel with this 3.3V. With a full base-emitter on voltage drop across predrivers and drivers, the balance of voltage results in approximately .35V drop across the bias resistors in the positive half, and about .5V across the bias resistor in the negative half. Q18 conduction (and thus bias) is adjustable.

A diode string prevents excessive charge build up within the high conduction output devices when off. Flyback diodes shunt back-EMF pulses from reactive loads to the power supply to protect output devices from dangerous reverse voltage levels. An output terminating circuit blocks RF on output lines from entering the ampliﬁ er through its output connectors.

3.5.2 Low Side (LS)

The Low Side (LS) operates quite differently. The power supply bridge rectiﬁ er is not ground referenced, nor is the secondary of the main transformer. In other words, the high voltage power supply floats with respect to ground, but ±Vcc remain constant with respect to each other. This allows the power supply to deliver +Vcc and -Vcc from the same bridge rectiﬁ er and ﬁ lter as a total difference in potential, regardless of their voltages with respect to ground. The LS uses inverted feedback from the HS output to control the ground reference for the rails (±Vcc). Both LS quadrants are arranged in a three-deep Darlington

+Vcc (Positive Rail)

Input signal

HIGH SIDE LOW SIDE

Figure 3.2 Grounded Bridge Output Topology

Load

(speaker)

Inverting Op-amp

-Vcc (Negative Rail)

Theory of Operation 3-3

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and are biased AB+B in the same manner as the HS.

When the ampliﬁ er output swings positive, the audio is fed to an op-amp stage where it is inverted. This inverted signal is delivered directly to the bases of the positive (NPN) and negative (PNP) LS predrivers. The negative drive forces the LS PNP devices on (NPN off). As the PNP devices conduct, Vce of the PNP Darlington drops. With LS device emitters tied to ground, -Vcc is pulled toward ground reference. Since the power supply is not ground referenced (and the total voltage from +Vcc to -Vcc is constant) +Vcc is forced higher above ground potential. This continues until, at the positive ampliﬁ er output peak,

-Vcc = 0V and +Vcc equals the total power supply potential with a positive polarity. If, for example, the power supply produced a total of 70V from rail to rail (±35VDC measured from ground with no signal), the amplifier output would reach a positive peak of +70V.

Conversely, during a negative swing of the HS output where HS PNP devices conduct, the op-amp would output a positive voltage forcing LS NPN devices to conduct. This would result in +Vcc swinging toward ground potential and -Vcc further from ground potential. At the negative ampliﬁ er output peak, +Vcc = 0V and -Vcc equals the total power supply potential with a negative polarity. Using the same example as above, a 70V supply would allow a negative output peak of -70V. In summary, a power supply which produces a total of 70VDC rail to rail (or ±35VDC statically) is capable of producing 140V peak-topeak at the amplifier output when the grounded bridge topology is used. The voltage used in this example are relatively close to the voltages of the PB-1/460CSL.

3.6 Output Device Emulation Protection (ODEP)

To further protect the output stages, a specially developed ODEP circuit is used. It produces a complex analog output signal. This signal is proportional to the always changing safe-operatingarea margin of the output transistors. The ODEP signal controls the Voltage Translator stage by removing drive that may exceed the safe-operating-area of the output stage.

ODEP senses output current by measuring the voltage dropped across LS emitter resistors. LS NPN current (negative amplifier output) and +Vcc are sensed, then multiplied to obtain a signal proportional to output power. Positive and negative ODEP voltages are adjustable via two potentiometers. Across ±ODEP are a PTC and a thermal sense (current source). The PTC is essentially a cutoff switch that causes hard ODEP limiting if heatsink temperature exceeds a safe maximum, regardless of signal level. The thermal sense causes the differential between +ODEP and –ODEP to decrease as heatsink temperature increases. An increase in positive output signal output into a load will result in –ODEP voltage dropping; an increase in negative output voltage and current will cause +ODEP voltage to drop. A complex RC network between the ±ODEP circuitry is used to simulate the thermal barriers between the interior of the output device die (immeasurable by normal means) and the time delay from heat generation at the die until heat dissipates to the thermal sensor. The combined effects of thermal history and instantaneous dynamic power level result in an accurate simulation of the actual thermal condition of the output transistors.

The total effect is to deliver a peak to peak voltage to the speaker load which is twice the voltage produced by the power supply. Beneﬁ ts include full utilization of the power supply (it conducts current during both halves of the output signal; conventional designs require two power supplies per channel, one positive and one negative), and never exposing any output device to more than half of the peak to peak output voltage (which does occur in conventional designs).

Low side bias is established by a diode string which also shunts built up charges on the output devices. Bias is adjustable via potentiometer. Flyback diodes perform the same function as the HS ﬂ ybacks. The output of the LS is tied directly to chassis ground via ground strap.

Theory of Operation 3-4

3.7 VZ Power

VZ means Variable Impedance and is the name of Crown’s patented articulated power supply technol- ogy. It enables Crown to pack tremendous power into just 3½ inches of vertical rack space.

3.7.1 Background

A power supply must be large enough to handle the maximum voltage and current necessary for the ampliﬁ er to drive its maximum rated power into a specified load. In the process of fulfilling this requirement conventional power supply designs produce excessive heat, are heavy, and take up precious real estate. It’s no secret that heat is one of a power ampliﬁ ers worst enemies.

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MA-3600VZ Service Manual

According to Ohm’s Law, the bigger the power supply, the more heat the power transistors must dissipate. Also, the lower the resistance of the power transistors, the more voltage you can deliver to the load. But at the same time that you lower the resistance of the transistors, you increase the current passing through them, and again increase the amount of heat they must dissipate.

3.7.2 The VZ supply

An articulated power supply, like VZ, can circumvent much of this problem by reducing the voltage applied to the transistors when less voltage is required. Reducing the voltage reduces the heat. Since the amplifier runs cooler, you can safely pack more power into the chassis.

The VZ supply is divided into segments to better match the voltage and current requirements of the power transistors. Remember that audio signals like music are complex waveforms.

For music the average level is always much less than the peak level. This means a power supply does not need to produce full voltage all the time.

The VZ supply is divided into two parts. When the voltage requirements are not high, it operates in a parallel mode to produce less voltage and more current (Figure 3.3). In this mode the power transistors stay cooler and are not forced to needlessly dissipate heat. This is the normal operating mode of the VZ power supply.

VZ POWER SUPPLY

POWER TRANSISTOR

STAGE

SPEAKER LOAD

POWER TRANSISTOR

STAGE

Figure 3.3 VZ Supply in Parallel Mode

When the voltage requirements are high the VZ supply switches to a series mode to produce the higher voltage and less current (Figure 3.4). The ampliﬁ ed output signal never misses a beat and gets full voltage when it needs it—not when it doesn’t need it.

VZ POWER SUPPLY

POWER TRANSISTOR

SPEAKER LOAD

POWER TRANSISTOR

STAGE

Figure 3.4 VZ Supply in Series Mode

Sensing circuitry watches the voltage of the signal to determine when to switch modes. The switching circuitry is designed to prevent audible switching distortion to yield the highest dynamic transfer function—you hear only the music and not the ampliﬁ er. You get not only the maximum power with the maximum safety, you also get the best power matching to your load.

3.7.3 VZ Switch Control

The two halves of U03 form identical comparators that monitor the available voltage of DC supply V2 and compare it to the output voltage of the ampliﬁ er. When a positive going output voltage exceeds a predetermined ratio of the available supply voltage, U03 pin 1 produces a low voltage triggering U04. When triggered, the “Q” output of U04 changes from low to high driving the gates of FET’s Q00, Q01, and Q02. The other half of U03 (pin 7) reacts to negative going output voltage. Both halves of U03 receive V2 and ampliﬁ er output voltage differentially.

The time constant set by C18 and R16 on the input of U04 sets the maximum switch frequency of the supply. This time constant forces the supply to stay in the series mode regardless of ampliﬁ er condition for 200 ms. The reset pin of U04 (pin 4) forces the output of U04 low when FET damage conditions exist.

C16 and C17 provide hysteresis around the comparators of U03 to insure stable operation. VZ Protection Circuit Protecting high current transistors can be troublesome in circuits that do not provide convenient current sample points. FETs Q00-Q02 fall into this class of problems, but protection has been designed based on the following two conditions being present at the same time:

Theory of Operation 3-5

MA-3600VZ Service Manual

130366-1 Rev. A

• Higher than normal on-state drain to source voltage

• Gate drive present.

When both of these conditions exist, a reasonable assumption can be made that the FETs are operating in an area that if sustained will cause damage to the FETs. These two conditions are detected by U05 pins 5 and 7.

U05 detects gate drive to the FETs at pin 7. Pin 6 is a reference input with the reference voltage set by R22 in series with R19.

U05 detects excessive source to drain voltage on the

DISPLAY

BALANCED

INPUTS

XLR

1/4" PHONE

P.I.P.

BALANCE

GAIN STAGE

VARIABLE

GAIN STAGE

PANEL

ERROR AMP

VOLTAGE

TRANSLATOR

ODEP

VOLTAGE

TRANSLATOR

FETs at pin 5. R17 in series with R18 forms a voltage divider to pin 5 of U05. The reference is set by a voltage divider formed by R29, R20, and R22.

When both conditions are detected the outputs of U05 (pins 1 and 2) allow C20 to start charging through R23. After 20µS, C20 will be sufﬁ ciently charged to turn on the section of U05 whose output is pin 14, discharging C21. As C21 discharges, it turns on Q03 which pulls the non-inverting input low (pin 9). U05 pin 13 drives the reset pin of U04 low which removes gate drive from the FETs. This hysteresis makes the circuit auto-resetting. Every 10ms (set by C21 and R26) it will make another 20µs try at driving the FETs. R25 prevents Q03 from pulling the input of U05 below its negative supply.

+VCC

POSITIVE

HIGH SIDE

OUTPUT STAGE

NEGATIVE HIGH SIDE

OUTPUT STAGE

-VCC

NPN

OUTPUT

PNP

A (ODEP)

B (ODEP)

LVA

BIAS

SERVO

CURRENT

LIMIT

NFb

INVERTING

BALANCE

-1

BRIDGE

BIAS

NETWORK

+VCC

POSITIVE

LOW SIDE

OUTPUT STAGE

NEGATIVE LOW SIDE

OUTPUT STAGE

-VCC

NPN

PNP

(ODEP)

Figure 3.5 Typical Crown Grounded Bridge Ampliﬁ er Basic Block Diagram (One Channel Shown)

Theory of Operation 3-6

130366-1 Rev. A

4 Maintenance

4.1 Cautions and Warnings

DANGER: The outputs of this ampliﬁ er can produce LETHAL energy levels! Be very careful when making connections. Do not attempt to change output wiring until the ampliﬁ er has been off at least 10 seconds. WARNING: This unit is capable of producing high sound pressure levels. Continued exposure to high sound pressure levels can cause permanent hearing impairment or loss. User caution is advised and ear protection is recommended when using at high levels. WARNING: Do not expose this unit to rain or moisture. WARNING: Only properly trained and qualified technicians should attempt to service this unit. There are no user serviceable parts inside. WARNING: When performing service checks with the power off, discharge the main power supply ﬁ lter capacitors fully before taking any measurements or touching any electrical components. A 300-ohm 10-W resistor is recommended for this. Hold the resistor with pliers, as the resistor may become extremely hot. WARNING: Under load, with a sine wave signal at full power into both channels, the ampliﬁ er may draw in excess of 30 amperes from the AC service mains. WARNING: Do not change the position of the Mode Switch when the ampliﬁ er is turned on. If the position of this switch is changed while the amplifier is powered, transients may damage your speakers. WARNING: Heatsinks are not at ground potential. Simultaneously touching either heatsink and ground, or both heatsinks will cause electrical shock. CAUTION: Eye protection should be worn at all times when protective covers are removed and the ampliﬁ er is plugged in. CAUTION: Disconnect the power cord before installing or removing any cover or panel.

4.2 General Information

The following test procedures are to be used to verify operation of this ampliﬁ er. DO NOT connect a load or inject a signal unless directed to do so by the procedure. These tests, though meant for veriﬁ cation and alignment of the amplifier, may also be very helpful in troubleshooting. For best results, tests should be performed in order.

MA-3600VZ Service Manual

All tests assume that AC power is from a regulated AC source appropriate for the unit under test.. Test equipment includes an oscilloscope, a DMM, a signal generator, loads, and I.M.D. and T.H.D. noise test equipment.

4.3 Test Procedures

4.3.1 Standard Initial Conditions

Level controls fully clockwise. Stereo/Mono switch in Stereo. Sensitivity switch in 26 dB ﬁ xed gain position. Ambient Temperature: 20 to 30 degrees C. It is assumed, in each step, that conditions of the amplifier are per these initial conditions unless otherwise speciﬁ ed.

4.3.2 Test 1: DC Offset

Spec: 0 VDC, ±5 mV. Initial Conditions: Controls per standard, inputs

shorted. Procedure: Measure DC voltage at the output connectors (rear panel). There is no adjustment for output offset. If spec is not met, there is an electrical malfunction. Slightly out of spec measurement is usually due to U104/U204 out of tolorance.

4.3.3 Test 2: Output Bias Adjustment

Spec: 310 ±10 mVDC. Initial Conditions: Controls per standard, heatsink

temperature less than 40°C. Procedure: Measure DC voltages on the output PWA across R02, adjust R26 if necessary. Measure DC voltages on the output PWA across R21, adjust R23 if necessary. Repeat for second channel.

4.3.4 Test 3: ODEP Voltage Adjustment

Spec: Bias Per Chart, ±0.1V DC. Initial Conditions: Controls per standard, heatsink

at room temperature 20 to 30°C (68 to 86°F). Note: This adjustment should normally be performed within 2 minutes of turn on from ambient (cold) conditions. If possible measure heatsink temperature, if not measure ambient room temperature. Use this information when referencing the chart on the following page.

Mantenance 4-1

MA-3600VZ Service Manual

130366-1 Rev. A

°F °CV –ODEPV +ODEP

66 18.9 –11.31 11.31 68 20.0 –11.26 11.26 70 21.1 –11.20 11.20 72 22.2 –11.14 11.14 74 23.3 –11.09 11.09 76 24.4 –11.03 11.03 77 25.0 –11.00 11.00 78 25.6 –10.97 10.97 80 26.7 –10.91 10.91 82 27.8 –10.86 10.86 84 28.9 –10.80 10.80 86 30.0 –10.74 10.74 88 31.1 –10.69 10.69 90 32.2 –10.63 10.63 92 33.3 –10.57 10.57 94 34.4 –10.51 10.51

–ODEP Procedure: Measure pin 6 of U100 and, if necessary, adjust R121 to obtain V–ODEP as speciﬁ ed above. Measure pin 6 of U200 and, if necessary, adjust R221 to obtain V–ODEP as speciﬁ ed above. +ODEP Procedure: Measure pin 6 of U103 and, if necessary, adjust R132 to obtain V+ODEP as speciﬁ ed above. Measure pin 6 of U203 and, if necessary, adjust R232 to obtain V+ODEP as speciﬁ ed above.

4.3.5 Test 4: AC Power Draw

Spec: 100 Watts maximum quiescent. Initial Conditions: Controls per standard. Procedure: With no input signal and no load,

measure AC line wattage draw. If current draw is excessive, check for high AC line voltage or high bias voltage.

4.3.6 Test 5: Common Mode Rejection

Spec at 1KHz: –70 dB. Initial Conditions: Sensitivity switch in 0.775V Procedure: No load. Inject a 0 dBu (.775VRMS) 1K

Hz sine wave into each channel, one channel at a time, with inverting and non-inverting inputs shorted together (common mode). Adjust R512 for minimum A.C output of Channel 1, R612 for Channel 2. At the output measure less than –28 dBu (30.5mVRMS).

4.3.7 Test 6: Voltage Gain

Spec 26dB Gain: Gain of 20.0 ±3%. Spec 0.775V Sensitivity: ±12%. Spec 1.4V Sensitivity: ±12%. Initial Conditions: Controls per standard. Procedure: 8 ohm load connected. Inject a single

ended 0.775 VAC 1 kHz sine wave with the Sensitivity Switch in the 26 dB position. Measure 15.5 VAC, ±0.3 VAC, at the ampliﬁ er output. Switch the Sensitivity Switch to the 0.775V position. Adjust the level of the input signal so that the output is at rated power. Measure 0.775 VAC ±12% at the amplifier input. Switch the sensitivity switch to the 1.4V position Measure 1.4 VAC, ±12%, at the ampliﬁ er input.

4.3.8 Test 7: Phase Response

Spec: ±10° from 10 Hz to 20 kHz at 1 Watt. Initial Conditions: Controls per standard, 8 ohm

load on each channel. Procedure: Inject a 1 kHz sine wave and adjust for 1 Watt output (2.8 VAC). Check input and output signals against each other, input and output signals must be within 10° of each other.

IN OUT

Figure 4.1 Differentiator Circuit

Mantenance 4-2

.047µf

1k ohm

Figure 4.2 Differentiated wave form at current limit

130366-1 Rev. A

MA-3600VZ Service Manual

4.3.9 Test 8: Level Controls

Spec: Level controlled by level controls. Initial Conditions: Controls per standard. Procedure: No Load. Inject a 1 kHz sine wave.

With level controls fully clockwise you should see full gain. As controls are rotated counterclockwise, observe similar gain reduction in each channel. When complete, return level controls to fully clockwise position.

4.3.10 Test 9: Current Limit

Spec: Current Limit at 43 - 48 Amps Initial Conditions: Controls per standard. Procedure: Load each channel to 1 Ohm. Inject a 1

kHz differentiated (or 10% duty cycle) square wave. See ﬁ gure 4.1. Increase output level until current limit occurs. Current limit should occur at 43 - 48 Amps (43-48 Vpk). Disregard waveform overshoot. Observe clean (no oscillations) current clipping. See Figure 4.2 for differentiated wave form at current limit.

4.3.11 Test 10: Slew Rate & 10 kHz Square Wave

Spec: 30 - 40 V/µS. Initial Conditions: Controls per standard. Procedure: Load each channel to 8 ohms. Inject a

10 kHz square wave to obtain 90 volts zero-to-peak at each output. Observe the slope of the square wave. It should typically measure 30 to 40 V/µS. Also, the square wave must not include overshoot, ringing, or any type of oscillation. See Figure 4.3 for typical 10 kHz square wave response.

4.3.12 Test 11: Crosstalk

Spec: -60dB at 20 kHz. Initial Conditions: Controls per standard. Terminate input of channel not driven with 600 ohms.

Procedure: 8 ohm load on each channel. Inject a 20 kHz sine wave into the Channel 1 input and increase output level to 80 VAC. Measure less than 80 mVAC at the output of Channel 2. Inject a 20 kHz sine wave into the Channel 2 input and increase output level to 80 VAC. Measure less than 80 mVAC at the output of Channel 1.

4.3.13 Test 12: Output Power

Spec at 8 Ohm Stereo: ≥ 1125W at 0.1% THD. Spec at 4 Ohm Stereo: ≥ 1625W at 0.1% THD. Spec at 2 Ohm Stereo: ≥ 1800W at 0.1% THD. International 8 Ohm Stereo: ≥ 945W at 0.1% THD. International 4 Ohm Stereo: ≥ 1255W at 0.1% THD. International 2 Ohm Stereo: ≥ 1490W at 0.1% THD. Initial Conditions: Controls per standard. Procedure: Load each channel to 8 ohms. Inject a

1 kHz sine wave and measure at least 94.67 VAC at the output of each channel. Load each channel to 4 ohms. Inject a 1 kHz sine wave and measure at least

80.62 VAC. Load each channel to 2 ohms. Inject a 1 kHz sine wave and measure at least 60.00 VAC. All power measurements must be at less than 0.1% THD. For international units, calculate output voltage with above power speciﬁ cations.

4.3.14 Test 13: Reactive Loads

Spec: No oscillations. Safe with all types of loads. Initial Conditions: Controls per standard. Procedure Capacitive: Load each channel to 8

ohms in parallel with 2 µF. Inject a 20 kHz sine wave with 48 VAC output for 10 seconds. Procedure Inductive: Load each channel to 8 ohms in parallel with 159 µHenries. Inject a 1 kHz sine wave with 36 VAC output for 10 seconds.

Figure 4.3 10 kHz square wave response Figure 4.4 ODEP limiting wave form

Mantenance 4-3

MA-3600VZ Service Manual

130366-1 Rev. A

Procedure Torture: Load each channel with the primary (red and black leads) of a PSU transformer (D 7040-5). Inject a 35 Hz sine wave for an output level of 89.5 Vrms, for 10 seconds. Procedure Short: Inject a 60 Hz sine wave with 30.0 VAC at the amplilﬁ er output. After establishing signal, short the output for 10 seconds.

4.3.15 Test 14: ODEP Limiting

Spec: ODEP Limiting occurs per the procedure. Either channel controls limiting in Parallel Mono Mode. Initial Conditions: Controls per standard; rag or other obstruction blocking fan so that it does not turn. Procedure: Load the ampliﬁ er to 2 ohms on each channel. Inject a 60 Hz sine wave and adjust for 30 Vrms at the output. After a few minutes observe a wave form similar to Figure 4.4. Both positive and negative alternations must show the distinctive waveform. There is no requirement of symmetry between positive and negative alternations. There is no requirement of uniformity from channel to channel. Remove the input signal from both channels and allow the ampliﬁ er to cool for a few minutes. Switch the ampliﬁ er to Parallel Mono and remove the load from Channel 1. Inject the signal into Channel 1 and observe that ODEP limiting occurs at the output of both channels. Remove the load from Channel 2, and install the load on Channel 1. Again, observe that both channels limit. Return all ampliﬁ er controls to standard initial conditions. Remove the fan obstruction.

4.3.16 Test 15: LF Protection

Spec: Ampliﬁ er mutes for low frequency. Initial Conditions: Controls per standard. Procedure: No load. Inject a 0.5 Hz, 10 volt peak-topeak, square wave, or a 1Hz, 17 volt peak-to-peak, sine wave into each channel and verify that each channel cycles into mute.

4.3.17 Test 16: Signal to Noise Ratio

Spec: 100 dB below rated 8 ohm power 20 Hz to 20 kHz. 105 dB A-Weighted.

Initial Conditions: 26dB Sensitivity. Short inputs. Procedure: Load each channel to 8 ohms. Measure

less than 950 µV at the output of each channel (20 Hz-20 kHz bandpass ﬁ lter).

4.3.18 Test 17: Turn On Transients

Spec: No dangerous transients. Initial Conditions: Controls per standard. Procedure: From an off condition, turn on the ampliﬁ er

and monitor the output noise at the time of turn on. Note: Turn on noise may increase signiﬁ cantly if the ampliﬁ er is cycled off and on.

4.3.19 Test 18: Turn Off Transients

Spec: No dangerous transients. Initial Conditions: Controls per standard. Procedure: From an on condition, turn off the ampliﬁ er

and monitor the output noise at the time of turn off. Note: Turn off noise may increase signiﬁ cantly if the ampliﬁ er is cycled off and on.

4.3.20 Test 19: Intermodulation Distortion

Spec at 0 dB Output: 0.02%. Spec at –35 dB Output: 0.05%. Initial Conditions: Controls per standard. Procedure: Load each channel to 8 ohms. Inject a

SMPTE standard IM signal (60 Hz and 7 kHz sine wave mixed at 4:1 ratio). Set the 60 Hz portion of the sine wave to 72 Volt RMS. Set the 7 kHz portion to 25%. With an IM analyzer measure less than 0.02% IMD. Repeat test at –35 dB (reference 72 Volt RMS, 60 Hz portion) and measure less than 0.05% IMD.

4.3.21 Test 20: High Line Cutout

Spec: 10% - 12% above nominal. Initial Conditions: Controls per standard. Procedure: Using an AC line variac, increase the

line voltage until the unit goes into standby. The unit should fo into standby at 10% - 12% above the nominal (120V U.S. units).

4.3.22 Post Testing

After completion of testing, if all tests are satisfactory, the amplifier controls should be returned to the positions required by customer. If conditions are unknown or unspecified, factory settings are as follows: Level Controls: 9 to 11 O’Clock. Sensitivity Switch: 0.775V U.S., 1.4V International. Stereo/Mono Switch: Stereo. Ground Lift: Lift. Power: Off.

Mantenance 4-4

130366-1 Rev. A

5 Parts

5.1 General Information

Replacement parts for this Crown ampliﬁ er can be ordered from the Crown Parts Department.

PART PRICES AND AVAILABILITY ARE SUBJECT TO CHANGE WITHOUT NOTICE.

5.2 Ordering and Receiving Parts

When ordering parts, be sure to give the product model, and include a description and part number from the parts listing. Price quotes are available on request.

5.2.1 Terms

Normal terms are prepaid. Net-30 Days applies to only those having pre-established accounts with Crown. The Crown Parts Department does accept Visa or Master Card. If prepaying, the order must be packed and weighed before a total bill can be

MA-3600VZ Service Manual

established, after which an amount due will be issued and shipment made upon receipt of payment. New parts returned for credit are subject to a restocking fee, and authorization from the Crown Parts Department must be obtained before returning parts for credit.

5.2.2 Shipment

Shipment will normally be made via UPS, or best other method unless you specify otherwise. Shipments are made to and from Elkhart, Indiana USA, only. Established accounts with Crown will receive shipment freight prepaid and will be billed. All others will receive shipment on a C.O.D. or prepayment (check or credit card) basis.

5.3 Mechanical Parts

This section includes a mechanical part list for this product. All serviceable parts and assemblies will have a Crown Part Number (CPN) listed in this chapter. The parts listed are current as of the date printed. Crown reserves the right to modify and improve its products for the beneﬁ t of its customers.

Crown Customer Service

Technical Support Group

Factory Service

Parts Department

Mailing Address: P.O. Box 1000, Elkhart IN 46515

Shipping Address: Plant 2 S. W.

1718 W. Mishawaka Rd., Elkhart IN 46517

Phone: (219) 294-8200

Toll Free: (800) 342-6939

Fax: (219) 294-8301

http://www.crownaudio.com

Parts 5-1

MA-3600VZ Service Manual

130366-1 Rev. A

Parts 5-2

Figure 5.1 Top Chassis Assembly

130366-1 Rev. A

MA-3600VZ Service Manual

5.3.1 Top Chassis Assembly

Refer to Figure 5.1 for Exploded View

Item Quantity Description Part # (CPN)

Not Pictured

Front Assembly

Chassis

Heatsink Assembly

Paper Shroud

Channel 1 B-L Switch Assembly

Power Transformer 120VAC 60Hz Domestic

Power Transformer 230VAC 50Hz E17CE

Transformer Plate

#8 Nylon Shoulder Washer

#8 Int Star Washer

Screw, 8-32 x 2.75 MSCR PNHD Zinc

Fan Assembly

Top Cover

Back Panel Assembly

Fuse, 1A 3AG 1.25 x .25

Control PWA

1/4 PC BD Support

star washer

Screw, 6-32 x.31 TORX PNHD STAR

Channel 2 B-L Switch Assembly

Bottom Cover

Insulator, 11 x 15 Transformer

Cable Tie Mount

see Section 5.3.3

F12621-3

see Section 5.3.3

see Section 5.3.6

see Section 5.3.8

D 8867-0

see Section 5.3.5

D 8874-6

D8876-1

F12588-4

A10099-5

A10094-6

A10089-10844

see Section 5.3.7

F12544J6

see Section 5.3.4

A10285-10

see Section 5.4

C 6032-4

included with screw

103433-70605

see Section 5.3.6

F12609-8

D8249-1

C 6918-4

Parts 5-3

MA-3600VZ Service Manual

130366-1 Rev. A

Parts 5-4

Figure 5.2 Bottom Chassis Assembly

130366-1 Rev. A

MA-3600VZ Service Manual

5.3.2 Bottom Chassis Assembly

Refer to Figure 5.2 for Exploded View

Item Quantity Description Part # (CPN)

Chassis

Pad, VZ Thru Hole

Note: use CPN #D 7679-0 with Output PWB

P10316-1 and earlier.

Output PWA

6-32 x .312 Pan HD T15 Screw

Driver Bracket

Screw, 6-32 x.312 Torx

Spacer, .75 Plastic

Spacer, 1.0 Plastic

Main PWA

Screw, 8-18 x 1.375 PNHD MSCR Zinc

Nylon Washer

Board Support, Plastic

Slip Collar

Sil Pad, 1.12 x 5 60

see Section 5.3.1

D7839-0

See Section 5.4

A10315-1

D8300-2

103415-70605

C6914-3

C6913-5

See Section 5.4

A10109-10822

D4137-2

C6912-7

A10192-1

D8440-6

Parts 5-5

MA-3600VZ Service Manual

130366-1 Rev. A

Parts 5-6

Figure 5.3 Front Assembly

130366-1 Rev. A

MA-3600VZ Service Manual

5.3.3 Front Assembly

Refer to Figure 5.3 for Exploded View

Item Quantity Description Part # (CPN)

Foam Filter

Screw, #8 x 1.00 Type AB Flat HD

Nylon Spacer

Grille Clip

Bottom Cover

Knob

Overlay

Display Panel

Handle

Panel Cap

Screw, #6-32 x .75 FLTHD TT

End Cap

Screw, 8-18 x 1.375 PNHD

Screw, 4-40 x .37 Taptite Pan

Display PWA

5KOhm Linear 31 Detent Pot 15MM Shaft

Screw, 6-32 x .25 RDHD

Washer, #6 Int Star

Screw, 6-32 x ,437 Socket Cap

Switch, DPST Pushbtn 6A 250VAC

Chassis

Lower Grille Extrusion

Push Button, .75 Threaded

Panel Cap Spacer

Self-Stick Rubber Feet

Insulator, 11 x 15 Transformer

.5 x .136 Nylon Washer

Velcro Tape

Grille Assembly (includes Bottom Cover)

D7696-4

A10103-10816

A10101-12

A10173-1

F12609-8

D6265-9

D 9148-4

F12887-0

D8048J6

D8049J4

C10258-9

D8052J8

A10086-10824

C5961-5

See Section 5.4

C7280-8

A10086-10604

A10094-3

A10092-20607

C10180-5

see Section 5.3.1

D8752-4

D6013-3

F12647-8

C3342-0

D8249-1

A10101-5

D5796-6

M46504-3

Note: Old style grilles with the one-piece ﬁ lter behind the grille are no longer available. If an older ampliﬁ er needs a new grille, the only option is to convert it to the new style by ordering CPN #M46504-3, which includes the bottom cover, grille extrusion, ﬁ lters and necessary hardware. New grilles will not ﬁ t onto old bottom covers.

Parts 5-7

MA-3600VZ Service Manual

130366-1 Rev. A

Figure 5.4 Back Panel Assembly

Parts 5-8

130366-1 Rev. A

MA-3600VZ Service Manual

5.3.4 Back Panel Assembly

Refer to Figure 5.4 for Exploded View

Item Quantity Description Part # (CPN)

Dual Binding Post

Screw, 8-32 x .37 RDHD MSCR

#8 Int Star Washer, Black

Standard PIP Assembly

Power Cord, NEMA TT-30P Plug, Domestic

Power Cord, HAR 230VAC 15A Plug, E17CE

Strain Relief

Edge Connector

Circuit Breaker, 15A, Domestic

Circuit Breaker, 8A, E17CE

#4 Int Star Lockwasher

Screw, 4-40 x .62 RDHD

Jumper, 4 Position Ground

Back Panel

Washer, #6 Int Star

Screw, 6-32 x .312 Pan HD T15 Taptite

Aluminum Spacer

PWB, PIP Interconnect

Cable W/Terminals

Daisy Ribbon Cable

2-Position Jumper

C10184-7

A10086-70806

A10094-5

See Section 5.3.9

D8247-5

D8844-9

C7315-2

C 6821-0

C10169-8

C10171-4

A10094-2

A10086-10410

D8855-5

F12864-9

A10094-3

C 9491-9

A10100-7

101240-1

D7623-8

D8573-4

F12812-8

Parts 5-9

MA-3600VZ Service Manual

130366-1 Rev. A

LEFT

Figure 5.5 Channel 1 Bi-Level Switch Assembly

Parts 5-10

+ 74 hidden pages

Crown MA-3600, MA-3600-VZ, Macro-Tech 3600, Macro-Tech 3600-VZ Service manual

Revision History

Table of Contents

1 Introduction

1.1 Introduction

1.3 Scope

1.4 Warranty

2.1 Performance

2.2 Power

2.3 Controls

2.4 Indicators

2.5 Input/Output

2.7 Construction

2.6 Protection

3 Theory of Operation

3.1 Overview

3.2 Features

3.3 Front End Operation

3.3.1 Balanced Gain Stage (BGS)

3.3.2 Variable Gain Stage (VGS)

3.3.3 Error Amp

3.4.1 Voltage Translators

3.5 Grounded Bridge Topology

3.5.1 High Side (HS)

3.5.2 Low Side (LS)

3.6 Output Device Emulation Protection (ODEP)

3.7 VZ Power

3.7.1 Background

3.7.2 The VZ supply

3.7.3 VZ Switch Control

4 Maintenance

4.1 Cautions and Warnings

4.2 General Information

4.3 Test Procedures

5 Parts

5.1 General Information

5.2 Ordering and Receiving Parts

5.3 Mechanical Parts

5.3.1 Top Chassis Assembly

5.3.2 Bottom Chassis Assembly

5.3.3 Front Assembly

5.3.4 Back Panel Assembly