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1、 A6000GTi Car Audio Power Amplifier Service Manual 2003 by Crown Audio, Inc., P.O. Box 1000, Elkhart, Indiana 46515-1000 U.S.A. Telephone: 574-294-8000. Trademark Notice: Crown is a registered trademark of Crown International, Inc; JBL is a registered trademark of JBL. Other trademarks are the prope
2、rty of their respective owners. 137159-1 11/03 Rev. 1 RadioFans.CN 收音机爱 好者资料库 137159-1 Rev. 1 A6000GTi Service Manual 2003 Crown Audio, Inc. II 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
3、possible situation, which may arise during installation, operation or maintenance. If you need special assistance beyond the scope of this manual, please contact the JBL Technical Support Group. This document contains data proprietary to Crown Audio, which was developed at private expense. Crown Aud
4、io reserves all rights in connection with this document and in the subject matter presented therein. The recipient hereby acknowledges these rights and shall not, without Crown Audios prior written permission, copy, disclose or divulge this document in whole or in part to third parties or use it for
5、 any purpose other than that for which it was delivered to the recipient. TO PREVENT ELECTRIC SHOCK DO NOT REMOVE TOP OR BOTTOM COVERS. REFER SERVICING TO QUALIFIED SERVICE PERSONNEL. TO REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE! The exclamation point triang
6、le is used to alert the user to important operating or maintenance instructions. RadioFans.CN 收音机爱 好者资料库 137159-1 Rev. 1 A6000GTi Service Manual 2003 Crown Audio, Inc. III Revision History Revision Number Date Comments Rev. 1 11-2003 Initial Draft RadioFans.CN 收音机爱 好者资料库 137159-1 Rev. 1 A6000GTi Ser
7、vice Manual 2003 Crown Audio, Inc. IV This page intentionally left blank 137159-1 Rev. 1 A6000GTi Service Manual 2003 Crown Audio, Inc. V Table of Contents 1. INTRODUCTION . 1-1 1.1. THE A6000GTI CAR AMPLIFIER . 1-1 1.2. SCOPE . 1-1 1.3. WARRANTY. 1-1 2. SPECIFICATIONS . 2-1 2.1. OUTPUT POWER . 2-1
8、2.2. PERFORMANCE . 2-1 2.3. CONTROLS however, some important information is duplicated in the Service Manual. NOTE: THE INFORMATION IN THIS MANUAL IS INTENDED FOR USE BY AN EXPERIENCED TECHNICIAN ONLY! 1.1. The A6000GTi Car Amplifier The A6000GTi is an extremely high output audio amplifier designed
9、for automotive use, providing high power amplification from 20Hz 400Hz with minimum distortion. The A6000GTi features Crowns patented, awarded-winning BCA (Balanced Current Amplifier) engineering, for superior power output, increased efficiency, legendary Crown sound and extraordinary reliability. O
10、ther features include parallel mode operation for driving loads below 2 Ohms, selectable 12/24 dB/octave crossover slope, phase adjustment and DBO (Dynamic Bass Optimization). 1.2. Scope This Service Manual is intended to apply to all versions of the A6000GTi amplifier. The Parts Listings include pa
11、rts specific for all versions. Parts are available from the Crown Parts Department. 1.3. 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. All war
12、ranty service should be referred to the Crown Factory or JBL Authorized Warranty Service Center. See Figure 1.1 for a copy of the Warranty. To find the location of the nearest Authorized Warranty Service Center or to obtain instructions for receiving Factory Service, please contact the JBL Technical
13、 Support Group. If you are an Authorized Warranty Service Center and have questions regarding the warranty of a product, please contact the JBL Technical Support Group. JBL Technical Support Phone: (516) 255-4JBL Phone: (516) 255-4525 Web Page: Customer Support Factory Service Parts Department Maili
14、ng Address: P.O. Box 1000, Elkhart, IN 46517 Shipping Address: Plant 2 S. W. 1718 W. Mishawaka Rd., Elkhart IN 46517 Phone: (574) 294-8200 Fax: (574) 294-8301 137159-1 Rev. 1 A6000GTi Service Manual 2003 Crown Audio, Inc. Introduction 1-2 Figure1.1 JBL Warranty 137159-1 Rev. 1 A6000GTi Service Manua
15、l 2003 Crown Audio, Inc. Specification 2-1 2. Specifications 2.1. Output Power A6000GTi Power Chart Maximum power 100Hz With 0.1% THD 2 ohm Dual 3000W 4 ohm Bridged 6000W 1 ohm Parallel 6000W Load Impedance: Safe with all types of loads. Rated for 2 ohms in dual mode, 4 ohms in Bridged and 1 ohm in
16、Parallel. Required Battery Voltage: 10.0-16.0 VDC DC Line Current: For 6000W: 700A; At idle: Amp draws 12.0A and no more than 200 watts. 2.2. Performance Frequency Response: 3dB from 10Hz to 200Hz at 1 watt. Phase Response: 0 to 180 degrees deviation from 20Hz to 320Hz. Signal to Noise Ratio, A-Weig
17、hted, 20Hz to 320Hz: Better than 100dB below rated 100Hz power. Total Harmonic Distortion (THD): 100Hz rated power 0.1% or less THD Damping Factor: Greater than 1000 from 10Hz to 400Hz Common Mode Rejection (CMR): Better than 70dB from 20Hz to 100Hz. 137159-1 Rev. 1 A6000GTi Service Manual 2003 Crow
18、n Audio, Inc. Specification 2-2 2.3. Controls LED will illuminate. Note that this LED will indicate whether signal is present at the amplifier but not whether it is being output from the amplifier. The compressor circuit is initiated by either the Input-Output Comparator (IOC) circuit or by the Ther
19、mal Limit Control (TLC) circuit. The IOC circuit is on the front-end board, and monitors the error amp signal. If the error amp signal becomes too large, indicating too much distortion on the output, the IOC signal will drop to 15 volts. This will cause the compressor drive circuit on the input boar
20、d to compress the inputs of the amplifier. U102 on the input board turns on Q100, which causes U103 to become active. U103 shunts the input signals together, thereby limiting the input to the amplifier. IOC will cause the CLIP LED to light only if it occurs long enough to be audible. The TLC circuit
21、 lights the THERMAL LED when the audio section is beginning to overheat. The LED can light before the TLC circuit begins to compress. The TLC circuit will be discussed in another section. The FAULT LED indicates that something catastrophic has happened to the amplifier. When the amplifier senses a f
22、ault condition, the audio section and power supply are both 137159-1 Rev. 1 A6000GTi Service Manual 2003 Crown Audio, Inc. Theory Of Operations 3-6 disabled, and a crowbar circuit is employed to drain the rail voltage to prevent any further damage. 3.2.4. Thermal Limit Control (TLC) The TLC circuit
23、is used to control the output of the amplifier while monitoring the temperature of the amplifier output devices and of the power supply switching devices. When the devices begin to overheat, the TLC circuit begins to compress the input signal, scaling back the output power until the unit is capable
24、of cooling itself again. On the input board, U104-C and U104-D form a window comparator with the input signal and two DC voltages created by U110-A and U110-D. As the unit begins to heat up, the window narrows, and when the input signal reaches the upper or lower limit on the window comparator, the
25、compressor drive circuit is activated and the input is compressed in the same manner as IOC. 137159-1 Rev. 1 A6000GTi Service Manual 2003 Crown Audio, Inc. Theory Of Operations 3-7 3.3. Power Supply 3.3.1. Switching Power Supply Operation The switching power supply is designed to take 12-volts in an
26、d convert it to +/- 150-volts out using a full bridge topology. The ring of mosfets around the transformer in the middle of the supply can be divided into 6 parallel H bridges, with each bridge having 2 mosfets per leg (for a total of 48 mosfets). The low voltage supply is a 48W push-pull. It suppli
27、es the large power supply and audio section with +/- 24-volts. The large power supply is specially designed to handle the high current demand of the audio section. The buss bars provide a low impedance path for the current into the full bridge. The orientation of the power mosfets maintains that low
28、 impedance path to maintain high efficiency. When the REM signal goes high, the low voltage power supply enables and generates the +/-24 volt rails. Once the voltage is about +/- 20 volts, the large power supply is enabled. The 6 parallel H bridges begin switching in unison. The PWM chip for the lar
29、ge power supply has soft start circuitry to decrease the inrush current demands of the amplifier. The H bridges create a 24 volts peak-to-peak square wave at a frequency of approximately 1000 Hz. The transformer has a turns ratio of 12:1, and the output voltage is stepped up to 288 volts peak to pea
30、k. The AC voltage is rectified to +/-144 volts DC. These are the rail voltages for the audio section. 3.3.2. Switching Power Supply Protection Circuit The power supply is equipped with crowbar circuitry to disable itself and drain the rails if the amplifier senses DC on the speaker outputs. The powe
31、r supply will also protect itself from over voltage and under voltage situations. The power supply is unregulated, so as battery voltage increases, rail voltage increases. For 16 volts in, the rail voltage will be 192 volts. The rail capacitors are only rated for 200 volts, so the power supply will
32、shut down to prevent an over voltage situation. The power supply is also equipped with thermal circuitry to compress the audio section when the power supply is overheating. This decreases the power demand and allows the power supply to cool down. 3.3.3. (LVPS) Low Voltage Power Supply Operation The
33、low voltage power supply is a switch mode power converter that uses a push pull topology. U8 is a SG3525AP pulse width modulator (PWM). The PWM regulates the output voltage to +24 volts by controlling the switching times of Q50 and Q54, which are IRF540N mosfets rated for 100V 33A. The transformer,
34、T2, has a center taped primary and secondary. The PWM alternates the on time of Q50 and Q54 at a frequency of 125kHz, synchronized with the main system clock, to apply voltage to their respective sides of the primary. This alternating voltage is multiplied by the turns ratio of the 137159-1 Rev. 1 A
35、6000GTi Service Manual 2003 Crown Audio, Inc. Theory Of Operations 3-8 transformer, then rectified by the diodes on the secondary (D8, D9, D11, D12), and filtered by L7 with C43 and by L8 with C49 to give the +/-24 volt outputs. The +24 volt is monitored by the PWM thru the resistor divider formed b
36、y R60 and R59. The PWM is equipped with soft start circuitry and pulse-by-pulse current limit to prevent the core from saturating. The current limit is accomplished by comparing the voltage across R58, which is a 0.04 ohm resistor, to a set voltage limit of 0.65 volts. U18 is the comparator that per
37、forms this function. The output of U18 is tied to the shutdown pin of the PWM and to a 5-volt pull up resistor. Note: The supply is designed to operate in continuous current mode (CCM), meaning it always supplies current on both the plus and minus 24-volt rails. If the power supply is operated witho
38、ut the audio section connected thru the ribbon cable, the 24 volt rail goes into discontinuous current mode, and the voltage jumps to 50 volts. The filter capacitors on the negative rail are only rated to 35 volts, so operating in this mode for more then a few seconds will require the replacement of
39、 C53 and C54. 137159-1 Rev. 1 A6000GTi Service Manual 2003 Crown Audio, Inc. Maintenance 4-1 4. Maintenance 4.1. Where to Begin Effective repair involves three basic steps: 1) Determine the symptom(s) of the problem 2) Identify the cause(s) of the symptom(s) 3) Repair the unit to eliminate the cause
40、(s) To determine the symptoms, you will want to get as much information from the user as possible. Get as much information as you can about the system and how the amplifier is used. There is always the possibility that the problem will show up only if used in a specific way. Once you have all the in
41、formation about the symptom(s), it is time to inspect the amplifier. A careful visual inspection is valuable for most problems, which you may encounter. To inspect the inside of the amplifier remove the cover as described in Section 4.3.1. Begin the inspection by looking for anything abnormal, like
42、loose connectors, broken wires and burnt or visibly damaged components. Inspect the printed circuit assemblies for broken traces and loose connections. Be thorough. The time you spend visually inspecting the amp is time well spent. 4.2. Surface Mount Technology The A6000GTi amplifier uses surface mo
43、unt technology in its design. There are several advantages to using surface mount technology (SMT), including; (1) surface mount devices (SMDs) are much smaller, and are mounted to the surface of the board, so more components can be placed on the board. (2) Components can be attached to both sides o
44、f the board, allowing the board size to be reduced. (3) SMT boards are lighter and provide better electrical performance and signal speed. Of course, there are also things to watch out for with SMT. (1) The placement of the components on the board, not through a hole, makes the components and solder
45、 joint more susceptible to damage. (2) Rework of SMDs can often require specialized tools, equipment, or training. (3) SMDs are very small and can be difficult to handle, see, and identify. Remember that on some of the boards, the SMDs are GLUED to the bottom of the board. This is done for manufactu
46、ring purposes. Take care not to damage components while trying to remove them from the surface of the module. 137159-1 Rev. 1 A6000GTi Service Manual 2003 Crown Audio, Inc. Maintenance 4-2 4.3. Disassembly for Inspection identify the cause of the symptoms; repair the unit to eliminate the cause. Please troubleshoot based on the order listed below. 4.4.1. Power Supply Caution: Before plugging the 6-conductor cable into the audio section, always make sure the voltage on the outer pins of the cable and on the audio section is less then 5 volts. Failure to do so
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