Mackie-M1200-pwr-sm1维修电路原理图.pdf

M1400 / M1400i / M1200 SERVICE MANUAL 1998 MACKIE DESIGNS, INC. 820-179-00 Version 1.2 RadioFans.CN 收音机爱 好者资料库 Go To Bulletins Page 3 is interactive CAUTION AVIS RISK OF ELECTRIC SHOCK DO NOT OPEN RISQUE DE CHOC ELECTRIQUE NE PAS OUVRIR CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK DO NOT REMOVE THE COVER NO USER SERVICEABLE PARTS INSIDE REFER SERVICING TO QUALIFIED PERSONNEL WARNING: TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE THIS PRODUCT TO RAIN OR MOISTURE TO PREVENT ELECTRIC SHOCK, DO NOT USE THIS POLARIZED PLUG WITH AN EXTENSION CORD, RECEPTACLE OR OTHER OUTLET UNLESS THE BLADES CAN BE FULLY INSERTED TO PREVENT BLADE EXPOSURE. ATTENTION: POUR EVITER LES RISQUES DE CHOC ELECTRIQUE, NE PAS ENLEVER LE COUVERCLE. AUCUN ENTRETIEN DE PIECES INTERIEURES PAR LUSAGER. CONFIER LENTRETIEN AU PERSONNEL QUALIFIE. AVIS:POUR EVITER LES RISQUES DINCENDIE OU DELECTROCUTION, NEXPOSEZ PAS CET ARTICLE A LA PLUIE OU A LHUMIDITE. POUR PREVENIR LES CHOCS ELECTRIQUES NE PAS UTILISER CETTE FICHE POLARISEE AVEC UN PROLONGATEUR, UN PRISE DE COURANT OU UNE AUTRE SORTIE DE COURANT, SAUF SI LES LAMES PEUVENT ETRE INSEREES A FOND SANS LAISSER AUCUNE PARTIE A DECOUVERT. The lightning flash with arrowhead symbol within an equilateral triangle is intended to alert the user to the presence of uninsulated dangerous voltage within the products enclosure, that may be of sufficient magnitude to constitude a risk of electric shock to persons. Le symbole clair avec point de flche linterieur dun triangle quilatral est utilis pour alerter lutilisateur de la prsence linterieur du coffret de vlotage dangereux non isole dampleur suffisante pour constituer un risque dlctrocution. The exclamation point within an equilateral triangle is intended to alert the user to the presence of important operating and maintenance (servicing) instructions in the literature accompanying the appliance. Le point dexclamation lintrieur dun triangle de la prsence dinstructions importantes pour le fonctionnement et lentretien (service) dans le livret dinstrucion accompagnant Lappareil. CAUTION AVIS RadioFans.CN 收音机爱 好者资料库 TABLE OF CONTENTS INTRODUCTION. 2 SYSTEM OVERVIEW. 3 SUMMARY OF FEATURES .4 SPECIFICATIONS.6 CIRCUIT THEORY. 8 INPUT CIRCUITRY.8 POWER AMPLIFIER CIRCUITRY.8 PROTECTION CIRCUITS .9 THERMAL MANAGEMENT.10 SERVICE PROCEDURES.11 REQUIRED EQUIPMENT LIST .11 TROUBLESHOOTING TIPS - OUTPUT FAILURES.12 TEST AND BIASING PROCEDURE.13 PARTS.15 QUICK PARTS .15 CHASSIS ASSEMBLY.16 HEATSINK ASSEMBLY.18 COMPLETE PARTS LIST.20 SCHEMATICS / PCB LAYOUTS.23 INPUT PCB SCHEMATIC.23 INPUT PCB LAYOUT.24 DISPLAY PCB SCHEMATIC.25 DISPLAY PCB LAYOUT.26 MAIN PCB SCHEMATICS.27 MAIN PCB LAYOUT .30 SOFT START PCB SCHEMATIC.31 SOFT START PCB LAYOUT.32 RadioFans.CN 收音机爱 好者资料库 Click on any item to open that page M1200/M1400 SERVICE MANUAL INTRODUCTION2 INTRODUCTION This manual contains complete service information for the M1200, M1400 and M1400i audio power amplifiers. Operating instructions will be touched on briefly. For complete operating instructions refer to the owners manual. The FR Series M1200 and M1400 are high power audio amplifiers designed for professional applications. They feature audiophile quality sound, excellent stability, extensive protection circuitry, and legendary Mackie reliability. Patented Fast Recovery circuitry allows the M1200/M1400 to recover from clipping without generating undesirable artifacts. To service the M1200/M1400, technicians should be familiar with op-amps, discrete analog circuitry, and troubleshooting high power solid state amplifiers. Presentation of this manual does not constitute endorsement of qualifications by Mackie Designs. TECHNICAL SUPPORT Mackie Designs Technical Support Department is available 8AM - 5PM PST, Monday - Friday at 1-800-258-6883 (outside US call 011-425-487-4333) Please feel free to call with any questions (Better safe than sorry!). DISCLAIMER The information contained in this manual is proprietary to Mackie Designs, Inc. The entire manual is protected under copyright and may not be reproduced by any means without express written permission from Mackie Designs, Inc. SERVICE ON THE M1200/M1400 IS TO BE PERFORMED BY EXPERIENCED TECHNICIANS ONLY! ! SMD ! The M1200/M1400 makes extensive use of surface mount components. Servicing technicians should have the tools and experience to perform surface mount rework. RadioFans.CN 收音机爱 好者资料库 VERSION 1.1 SYSTEM OVERVIEW3 SYSTEM OVERVIEW This section provides a quick summary of the M1200/M1400s major features. It is not intended to take the place of the owners manual. It is included here to help servicing technicians familiarize themselves with the M1200/M1400. DIFFERENCES BETWEEN THE M1400, M1400i AND M1200 The M1200 and M1400 are electronically identical products with the following exceptions: 1. The M1400 has 12,000uF main filter caps, where the M1200 and M1400i have 10,000uF. 2. The M1400 and M1400i use a more powerful fan than the M1200. 3. The M1400 has Speakon connectors where the M1200 and M1400i have ” speaker outputs (both in addition to binding posts). The M1200 was discontinued in 1998 and replaced by the M1400i. Export M1400s also have a “Soft Start” circuit that is not installed on American units. FAST RECOVERY DESIGN Solid state power amplifiers have a reputation for sounding harsh when driven into clipping. The usual explanation is odd harmonics generated by hard clipping, but In fact much of the unpleasant sound is caused by latching and parasitic oscillations that occur as the amplifier recovers from clipping. TYPICAL AMPLIFIERMACKIE FR SERIES ARTIFACTS CAUSED BY LATCHING AND PARASITIC OSCILLATION Mackies Fast Recovery design recovers from clipping quickly without generating any undesirable artifacts. This performance is achieved by two unique design elements; the Full Symmetry Dual Differential front end provides excellent linearity while minimizing the need for negative feedback, and the Baker Clamp prevents output/driver device saturation. How these circuits operate is covered in depth in the circuit theory section. RadioFans.CN 收音机爱 好者资料库 M1200/M1400 SERVICE MANUAL SUMMARY OF FEATURES4 SUMMARY OF FEATURES FRONT PANEL 1. GAIN Detented gain controls adjust the level sent to each output section. The gain structure is designed so that a +4dBu (1.23V rms) input signal drives the amplifier to full rated power into 4. 2. METERS The M1200/M1400s meters indicate the relative output level of the amplifier referenced to full power. The SIG (signal present) senses the input prior to the gain control. 3. PROTECT The Protect LEDs light indicating the channel has been muted for one of the following reasons: 4 second turn on delay Output devices beyond Safe Operating Area (SOA), also lights SHORT LED(s). Heatsink temperature beyond 80 degrees Celsius. 4. SHORT The Short LEDs light to show that the amplifier has engaged protection due to a short or low impedance on the output. 5. TEMP STATUS The HOT LED lights to indicate that the amplifier has engaged protection due to heatsink temperature or power transformer core temperature. 6. POWER SWITCH This remarkable device requires years of study to full comprehend. OL - 3 - 6 - 2 0 -3 -6 -9 - 2 0 SIG O L SIG CH 1 30 28 26 20 2218 2 4 1 6 1 4 8 1.23v (+4dBu) SENSITIVITY GAIN /dBCH 2 PROTECT COL D HOT SHORT TEMP ST ATUS INTERNALSTATUS CH 1 CH 2 CH 1 1) Prevent output/driver transistors saturating, 2) Drive the LIMITER LDR. Referring to the left main amp schematic, Q27 is a common base amplifier, it will turn on if Q31s collector rises more than two diode drops above the +80V supply, preventing it from rising further. There are three diode drops between Q31s collector and the base of driver transistor Q28 (D3, D2, Q29Vbe). Q29 will never see a voltage greater than one diode drop below the +80V supply, even if the +80V supply fluctuates. Q27 also drives the limiter LDR LED U2A. The negative side has the same circuit mirrored. RadioFans.CN 收音机爱 好者资料库 VERSION 1.1 CIRCUIT THEORY9 PROTECTION CIRCUITS Refer to schematics on pages 27-29. The M1200/M1400 has two output protection circuits in addition to the rail fuses. The first mutes the amp if the output devices are loaded beyond their safe operating area (SOA). The second is a crowbar circuit that ensures the rail fuses blow if there is DC on the output. SOA PROTECTION The SOA protection circuit senses the voltage drop across the emitter resistors much like standard VI current limiting transistors. Q76 and Q77 will turn on if the emitter drop exceeds 1V. If they are on for long enough to charge C38 (through R159), the SOA protection circuit is activated by transistor switches Q79 and Q78. If SOA detection is tripped, the channel is muted by discharging C53 through R200 and D65, fan speed is increased, and the “SHORT” LED lights. DC CROWBARS The DC Crowbar circuit protects speakers in the event of an output failure by blowing all rail fuses. SCRs Q21-24 are used to short the +/- 80V supply supplies to ground. Output signal from both sides is fed through 100K resistors R90, R89 to C21, essentially forming a LPF. DC on either output will trigger comparator U4A (positive) or U4B (negative). The SCRs are then fired via driver transistors Q87, Q88. NOTE: The LM339 comparator IC is used extensively in the M1200/M1400. It differs from a standard op-amp used as a comparator in that it has an open collector output. If the voltage at the inverting input exceeds the non-inverting, the LM339s output switches to its negative supply. Otherwise, the output is open. RadioFans.CN 收音机爱 好者资料库 M1200/M1400 SERVICE MANUAL CIRCUIT THEORY10 THERMAL MANAGEMENT Refer to schematic on page 29. The M1200/M1400 T-Design Heatsink/Fan cools output devices evenly and does not collect dust on the circuitry. The fan operates at two speeds, controlled by the amplifier. An LM35DZ mounted in the center of the heatsink provides temperature information to the fan control and overtemp circuits. There is also a thermal breaker in the power transformer. FAN CONTROL CIRCUIT The fan voltage comes from a feedback regulator circuit formed by Q91 and Q92. The output voltage is programmed by the ratio of R209 to R211/ R207 (/=parallel). When the unit is powered up C83 charges through R241 providing a 40 second delay before the fan starts. As C83 charges, U6Ds output switches to -16V, starting the fan. Then U6As output switches to open, allowing U6B to increase the fan speed, if triggered. R240 and C82 give the fan extra voltage when starting. The fan speed is increased by U6B adding R211 in parallel with R207. (Q91 wants its base a diode drop above ground, so Q92 doubles its Emitter voltage). U6B is triggered by U4D to increase fan speed if; Channel 1 SOA protection is activated (U5C), OR Channel 2 SOA protection is activated (U5D), OR The heatsink is above 60 deg C (U5B) AND program is detected (U4C), OR The heatsink temperature is above 80 deg C (U5A). U6C and Q89 are used to reset the circuit on power down. Under normal operation C50 is charged via D57, Holding Q89 off. When power is removed C50 discharges and Q89 switches on as the rails collapse. When the voltage on Q89s collector falls below ground U6 switches to the negative rail discharging C82 and C83. THERMAL SHUTDOWN Extreme heatsink or transformer core temperature will activate OVERTEMP. U5A activates overtemp if the LM35DZ detects heatsink temperature above 80 deg C. Feedback resistor R137 rescales U5As voltage reference so that the heatsink must cool to below 50 deg C before overtemp is deactivated. Overtemp can also be activated by the power transformer thermal breaker (via Q89). In either case, both channel are muted via D69 and D66. RadioFans.CN 收音机爱 好者资料库 VERSION 1.1 SERVICE PROCEDURES11 SERVICE PROCEDURES MECHANICAL PROCEDURES The M1200/M1400 design allows easy removal of all components and assemblies. Disassembly and reassembly should be self evident. This manual has exploded diagrams in the parts section. Several important points concerning the assembly: 4 of the screws that secure the top cover also hold the front extrusion (curved piece) in place. When removing the top cover, be careful that the front extrusion is not dropped. If the MAIN PCB is removed, be sure the smaller head machine screws (750-050-04) are replaced next to the filter caps. The larger head machine screws can arc to the capacitor body. Be sure all tywraps are replaced and that no wires are in danger of being pinched in-between the cover and heatsink. REQUIRED EQUIPMENT LIST 30 MHz dual trace oscilloscope DMM (Must be capable of measuring 8mV DC with a minimum of 2 digits of accuracy, and down to .1) Sine wave oscillator / Function generator (20Hz - 20KHz) 4 load resistors (8 with a minimum 500W power rating) 10A / 120V Variac With AC voltmeter and a defeatable ammeter (1 Amp full range) or wattmeter (300 Watts full range) 0.1uF 400V film capacitor installed across dual banana plug 16 AWG shorting jumper installed across dual banana plug RECOMMENDED EQUIPMENT LIST (PERFORMANCE VERIFICATION) Distortion analyzer and low distortion oscillator. (Capable of resolving distortion as low as 0.002% from 20Hz to 20KHz) 2500W AC power source.