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Micro-Tech 2400 Amplifier Service Manual
POWER AMPLIFIER
SERVICE MANUAL
®
MICRO-TECH -2400
©1995 by CROWN INTERNATIONAL, INC.
Mailing Address: Shipping Address:
P.O. Box 1000 57620 C.R. 105
Elkhart, IN U.S.A. 46515-1000 Elkhart, IN U.S.A. 46517
® ® ®
Micro-Tech , ODEP and Crown are registered trademarks of Crown International, Inc.
K-SVCMT24
7-95
1
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Micro-Tech 2400 Amplifier 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: 57620 C.R. 105 Elkhart IN 46517 Phone: (800) 3
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Micro-Tech 2400 Amplifier Service Manual Table of Contents Introduction ............................................................. 4 Scope ...................................................................... 4 Warranty .................................................................. 4 Parts Information ..................................................... 5 Specifications .......................................................... 6 Voltage Conversion ......................................
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Micro-Tech 2400 Amplifier Service Manual Introduction This manual contains service information on Crown Each of the compact audio power amplifiers are power amplifiers. It is designed to be used in conjunc- designed for professional or commercial use. Provid- tion with the applicable Owner's Manual. However, ing high power amplification from 20Hz to 20KHz with some important information is duplicated in this Ser- minimum distortion, they feature balanced inputs with vice Manual in case the Own
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Micro-Tech 2400 Amplifier Service Manual Parts Information shipment on a C.O.D. or pre-payment (check or credit GENERAL INFORMATION card) basis. Later sections include both mechanical and electrical parts lists for this product. The parts listed are current TERMS as of the date printed. Crown reserves the right to modify and improve its products for the benefit of its Normal terms are pre-paid. Net-30 Days applies to customers. only those firms having pre-established accounts with Crown. If pre-
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Micro-Tech 2400 Amplifier Service Manual Specifications Unless noted otherwise, all specifications are based Input Impedance: Nominally 20K ohms balanced; 10K on driving an 8 ohm load per channel, both channels ohms unbalanced. driven, the sensitivity switch in the 26dB position, the AC supply is 120VAC at 60Hz. Crown specifications Output Impedance: <10 milliohms in series with <2 are guaranteed through the warranty period (normally microhenries. 3 years). Because our testing methods are more s
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Micro-Tech 2400 Amplifier Service Manual Voltage Conversion The 120 Volt 60 Hz version, sold in the United States, is not voltage selectable. It does not have a voltage selection board. This version is to be used only with 120 Volts and only with 60Hz. All other versions of the Micro Tech 2400 use a volt- age selection board. The following chart indicates different configurations of jumpers for different volt- ages. Note that the circuit breakers, fuse and transmotor may need to be changed to ac
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Micro-Tech 2400 Amplifier Service Manual Theory packaging of this model is designed for maximum OVERVIEW watt/price/weight/size value with user friendly fea- It should be noted that over time Crown makes im- tures. provements and changes to their products for various reasons. This manual is up to date as of the time of For additional details refer to the specification section, writing. For additional information regarding these or to the applicable Owner’s Manual. amplifiers, refer to the applic
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Micro-Tech 2400 Amplifier Service Manual Theory amplifies the difference between input and output The ODEP transistors steal drive as dictated by the signals, any difference in the two waveforms will ODEP circuitry (discussed later). The control/protec- produce a near open loop gain condition which in turn tion transistors act as switches to totally shunt audio to results in high peak output voltage. The output of the ground during the turn-on delay, or during a DC/LF or Error Amp, called the Er
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Micro-Tech 2400 Amplifier Service Manual Theory to the cutoff level under static (no signal) conditions. High Side (HS) This is because PNP devices require greater drive The High Side (HS) of the bridge operates much like current. a conventional bipolar push-pull output configuration. As the input drive voltage becomes more positive, the HS bias is regulated by Q18, the Bias Servo. Q18 is a HS NPN conducts and delivers positive voltage to the Vbe multiplier which maintains approximately 3.3V loa
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Micro-Tech 2400 Amplifier Service Manual Theory respect to each other. This allows the power supply to deliver +Vcc and -Vcc from the same bridge rectifier Low side bias is established by a diode string which and filter as a total difference in potential, regardless also shunts built up charges on the output devices. of their voltages with respect to ground. The LS uses Bias is adjustable via potentiometer. Flyback diodes inverted feedback from the HS output to control the perform the same funct
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Micro-Tech 2400 Amplifier Service Manual Theory POSITIVE +VOLTAGE +LVA HIGH SIDE TRANSLATOR -1 OUTPUT NPN STAGE ERROR BGS VGS AMP OUTPUT HIGH SIDE DEVICE BALANCED -1 BIAS EMULATION INPUTS SERVO PROTECTION NEGATIVE -VOLTAGE -LVA HIGH SIDE TRANSLATOR -1 OUTPUT PNP STAGE MAIN NEGATIVE FEEDBACK (NFb) LOOP POSITIVE LOW SIDE OUTPUT NPN STAGE LOW SIDE BIAS -1 DIODE STRING NEGATIVE LOW SIDE INVERTING OUTPUT BRIDGE PNP STAGE BALANCE Figure 3. Typical Crown Amplifier Basic Block Diagram (One Channel Shown
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Micro-Tech 2400 Amplifier Service Manual Electrical Checkout Procedures °F °C V V GENERAL INFORMATION –ODEP +ODEP 66 18.9 –10.31 10.31 The following test procedures are to be used to verify 68 20.0 –10.26 10.26 operation of this amplifier. DO NOT connect a load or 70 21.1 –10.20 10.20 inject a signal unless directed to do so by the proce- 72 22.2 –10.14 10.14 dure. These tests, though meant for verification and 74 23.3 –10.09 10.09 alignment of the amplifier, may also be very helpful in 76 24.4
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Micro-Tech 2400 Amplifier Service Manual Electrical Checkout Procedures TEST 6: VOLTAGE GAIN TEST 10: SLEW RATE & 10 KHZ SQUARE WAVE Spec 26dB Gain: Gain of 20.0 ±3%. Spec: 17 - 25 V/µS. Spec 0.775V Sensitivity: ±6%. Initial Conditions: Controls per standard. Spec 1.4V Sensitivity: +12%/–6%. Procedure: Load each channel to 8 ohms. Inject a 10 Initial Conditions: Controls per standard. kHz square wave to obtain 64 volts peak-to-peak at Procedure: No load connected. Inject a 0.775 VAC 1 each outp
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Micro-Tech 2400 Amplifier Service Manual Electrical Checkout Procedures Procedure Short: Inject a 60 Hz sine wave at 5 VAC TEST 16: SIGNAL TO NOISE RATIO minimum output. After establishing signal, short the Spec: 100 dB below rated 8 ohm power 20 Hz to 20 output for 10 seconds. kHz. 105 dB A-Weighted. TEST 14: ODEP LIMITING Initial Conditions: Controls per standard. Short inputs. Spec: No oscillation on ODEP Limiting wave form; Procedure: Load each channel to 8 ohms. Measure either channel contr
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Micro-Tech 2400 Amplifier Service Manual Parts List (Non-Module) SUPPLIMENTAL ITEMS CPN ITEM QTY D 4137-2 Nylon Thumbscrew Washer 4 C 3342-0 Feet, Black Self-Stick 4 A10087-71012 10-32 .75 Machine (Rack Screw) 4 K80603-2 MT Series Owners Manual 1 POWER SUPPLY CPN ITEM QTY D 7975-2 Power Cord (US Models) 1 A10793-0503G Power Cord (European plug) 1 D 8633-6 Power Transformer (120V 60 Hz only) 2 D 8631-0 Power Transformer (Universal Volt) 2 C 9508-0 Circuit Breaker, 15A (100V-120V) 2 C 8041-3 Circu
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Micro-Tech 2400 Amplifier Service Manual Parts List (Non-Module) OUTPUT ASSEMBLY CONT. (ONE PER CHANNEL) CPN ITEM QTY(PER CHANNEL) D 7665-9 Clip, TO-3P Mounting 2 D 7666-7 Bracket, TO-3P Heatsink 2 C 8813-5 Q318/Q418 Bias Servo MPSA18/MPS8097 1 B 5842-8 Tubing, #23 TFE Thin Wall Red (For C 8813-5) Request in Inches C 5826-0 S100/S200 Thermal Sense LM334Z 1 B 5464-1 Tubing, #24 Teflon Thin Wall (For C 5826-0) Request in Inches D 8774-8 PTC Thermal Sensor 95DEGC 1 A10315-1 Screw, 6-32-.56 Hex Wash
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Micro-Tech 2400 Amplifier Service Manual Parts List (Non-Module) MAIN CHASSIS ASSEMBLY CPN ITEM QTY D 8501-5 Cover, Top 1 D 8548-6 Cover, Bottom 1 A10110-70605 Screw, 6-32-.312 Taptite Ph (Covers) 16 M21447J3 Main Chassis 1 MISCELLANEOUS CPN ITEM QTY A10110-70812 8-32 x .750 Taptite Pnhd Screw 2 A10094-3 Washer, #6 Black Star 3 A10109-10822 Screw, 8-18-1.375 Pan Ph 2 A10192-1 Snap Bushing .5 4 C 6912-7 Tension Retainer Board Support 2 C 6913-5 Spacer Nut, 1 inch 2 C 6914-3 Spacer Nut, .75 inch 2
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Micro-Tech 2400 Amplifier Service Manual Module Information MODULE HISTORY The Micro Tech 2400 amplifier was introduced in January of 1995. Since then there have been several updates and revisions, some of which called for new modules. The following is a list of all modules used up to this date, July 1995. OUTPUT MODULES: (left and right are identical) Q43354-2 Original Output Module, still in production. Uses P10429-2 board. MAIN MODULES: Q43328-6 Original Main Module on D 8679-9 board. Used un
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Micro-Tech 2400 Amplifier Service Manual M46330-3 Fuse Module & Q43327-8 Display Module Parts List M46330-3 FUSE MODULE 2 C 5060-6 PC Mount Fuse Clip 11 C 7817-7 Tab, AMP .25 Faston PC Mount 1 P10425-0 MT-2400 Fuse Board For replacement fuse see Power Supply Parts List on page 16. Q43327-8 DISPLAY MODULE CAPACITORS C503 C603 C 6806-1 .01µF C507 C607 C 6809-5 220pF C701 C 6802-0 .47µF C702 C 6802-0 .47µF DIODES D701 C 3533-4 1N966B D702 C 3533-4 1N966B LED'S E502 E602 C 4342-9 Amber, MV5153 E701
