Go To Bulletins M•1400 / M•1400i / M•1200 SERVICE MANUAL 1998 MACKIE DESIGNS, INC. 820-179-00 Version 1.
CAUTION AVIS 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 ATTENTION: POUR EVITER LES RISQUES DE CHOC ELECTRIQUE, NE PAS ENLEVER LE COUVERCLE. AUCUN ENTRETIEN DE PIECES INTERIEURES PAR L'USAGER. CONFIER L'ENTRETIEN AU PERSONNEL QUALIFIE.
® TABLE OF CONTENTS INTRODUCTION............................................................. 2 SYSTEM OVERVIEW ....................................................... 3 SUMMARY OF FEATURES .....................................................................4 SPECIFICATIONS...................................................................................6 CIRCUIT THEORY ........................................................... 8 INPUT CIRCUITRY..........................................................
M•1200/M•1400 SERVICE MANUAL INTRODUCTION This manual contains complete service information for the M•1200, M•1400 and M•1400i audio power amplifiers. Operating instructions will be touched on briefly. For complete operating instructions refer to the owner’s manual. The FR Series M•1200 and M•1400 are high power audio amplifiers designed for professional applications. They feature audiophile quality sound, excellent stability, extensive protection circuitry, and legendary Mackie reliability.
VERSION 1.1 SYSTEM OVERVIEW This section provides a quick summary of the M•1200/M•1400’s major features. It is not intended to take the place of the owner’s manual. It is included here to help servicing technicians familiarize themselves with the M•1200/M•1400. DIFFERENCES BETWEEN THE M•1400, M•1400i AND M•1200 The M•1200 and M•1400 are electronically identical products with the following exceptions: 1. The M•1400 has 12,000uF main filter caps, where the M•1200 and M•1400i have 10,000uF. 2.
M•1200/M•1400 SERVICE MANUAL 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 4Ω. 2. METERS The M•1200/M•1400’s 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.
VERSION 1.1 REAR PANEL 1. SPEAKER OUTPUTS The M•1400 has Speakon connectors where the M•1200 has ¼” speaker outputs. Both models have binding posts. For bridged mono operation, the + output comes from channel one’s positive terminal and - from channel two’s positive. 2. INPUT The M•1200/M•1400 has both XLR and ¼” TRS inputs. They are electrically identical (wired in parallel). In bridged mono or parallel mono mode channel 2 input is disabled. 3.
M•1200/M•1400 SERVICE MANUAL SPECIFICATIONS Note: Power ratings are specified at 120VAC (U.S. and Canada) and 240VAC (Export) line voltages. CONTINUOUS AVERAGE OUTPUT POWER, BOTH CHANNELS DRIVEN: M•1200 225 watts per channel into 8 ohms from 20Hz to 20kHz, with no more than 0.025% THD 400 watts per channel into 4 ohms from 20Hz to 20kHz, with no more than 0.050% THD 600 watts per channel into 2 ohms from 20Hz to 20kHz, with no more than 0.
VERSION 1.1 RISE TIME: LIMITER SECTION: < 4.4µs Complementary Positive and Negative Peak Detecting SLEW RATE: Voltage Slew Rate > 50V/µs > 100V/µs bridged Current Slew Rate > 32A/µs at 2Ω INDICATORS: 6 meter LEDs per channel SIG (Signal Present), –20, –9, –6, –3, OL (Overload) CMRR: CH 1 & 2 PROTECT LEDs SHORT LEDs > 40 dB, 20Hz to 20kHz TEMP STATUS COLD/HOT LEDs LOAD ANGLE: 8(±jx) time independent at 8Ω 4(±jx) time dependent, T > 6 min. at 4Ω 2(1±jx) time dependent, T > 2 min.
M•1200/M•1400 SERVICE MANUAL CIRCUIT THEORY Much of the circuitry in the M•1200/M•1400 is self explanatory from the schematic. This section will explain the unique circuits and architecture. Samples in this section will refer to Channel 1 (Left) for circuitry that is identical on both channels. INPUT CIRCUITRY Refer to schematic on page 23. The signal path begins with the INPUT BOARD. Following Channel 1’s input, signal is fed to a unity gain differential op-amp, U1A.
VERSION 1.1 PROTECTION CIRCUITS Refer to schematics on pages 27-29. The M•1200/M•1400 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.
M•1200/M•1400 SERVICE MANUAL THERMAL MANAGEMENT Refer to schematic on page 29. The M•1200/M•1400 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.
VERSION 1.1 SERVICE PROCEDURES MECHANICAL PROCEDURES The M•1200/M•1400 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.
M•1200/M•1400 SERVICE MANUAL TROUBLESHOOTING TIPS - OUTPUT FAILURES After a catastrophic failure, it is likely that the four +/-80V supply fuses will be blown. Replace fuses and very slowly bring up the Variac while monitoring line consumption. It is likely that substantial line current will be pulled due to shorted output parts. At the same time, look for DC offset at the output. Offset of greater than +/- 2.8V will trigger the protection circuits and re-blow the four fuses.
VERSION 1.1 BIAS AND TEST PROCEDURE After the unit has been repaired, the following should be done to assure long term reliable operation. If a distortion analyzer is present, distortion specifications should be verified. 1. Adjusts bias in both channels (R1 & R51) for 8mV +/- 0.3mV at bias test points (J53 & J54) after unit has idled for a few minutes. With Full AC line voltage applied to unit, it will pull around 65W from the line (900mA at 120V). Measure for DC offset on both output connectors.
M•1200/M•1400 SERVICE MANUAL (THIS PAGE UNINTENTIONALLY LEFT BLANK), THOSE RESPONSIBLE HAVE BEEN PUT TO THE SWORD 14 SERVICE PROCEDURES
VERSION 1.1 PARTS QUICK PARTS FRONT PANEL FULL SYMMETRY DUAL DIFFERENTIAL HIGH CURRENT DESIGN CH GAIN /dB 1 20 22 2v 2 4 26 8 28 OL O L - 3 -3 - 6 -6 16 - 9 -9 14 - 2 0 1 8 - 2 0 3 v 2 2 2 0 8 3 01v 1v 1.23v (+4dBu) SIG SIG 2 2 24 v CH CH 1 2 SENSITIVIT Y ON INTERNALSTATUS PROTECT 2 6 30 SENSITIVITY CH GAIN /dB 3v 18 1 6 1 4 PROFESSIONALPOWER AMPLIFIER SHORT TEMP STATUS 2 8 OFF CH 1& 2 COL D 1.
M•1200/M•1400 SERVICE MANUAL CHASSIS ASSEMBLY 1 2 3 16 17 4 1 7 5 6 15 14 13 10 8 9 1 11 16 12 PARTS 18
VERSION 1.
M•1200/M•1400 SERVICE MANUAL HEATSINK ASSEMBLY 18 PARTS
VERSION 1.1 HEATSINK ASSEMBLY PARTS LIST ITEM # PART # DESCRIPTION 1 551-032-00 EXTR FAB HEATSINK - M1200 2 410-003-00 INSL SILPAD K6 W/ADHESIVE 3 055-081-00 PCB ASSY MAIN - 1200 3 080-072-01 PCB ASSY MAIN - M1400 3 080-072-02 PCB ASSY MAIN - M1400i 4 550-255-00 PIGGYBACK CLIP 5 700-058-02 MCH 4-40X1/2 SKT CLRZC 6 710-020-00 WASH NO.4 COMPRESSION 7 710-022-00 WASH FLAT NO.
M•1200/M•1400 SERVICE MANUAL COMPLETE PARTS LIST 040- Cables 055- Finished PCB Assys 100- Pots and Resistors 200- Capacitors 300- Semiconductors 400- Jacks/Connectors 500- Switches 510- Fuses 550- Chassis Metal 600- Transformers 601- Inductors 610- Wires and Cables 640- AC Line Cords 700- Hardware 760- Knobs/Plastic 790- Misc./Packing 800- Printed Material PART # DESCRIPTION PART # DESCRIPTION 040-033-02 RIB 28GA TRANS 20C 18IN 100-094-00 RES CF .
VERSION 1.1 PART # DESCRIPTION PART # DESCRIPTION 140-111-00 RES TF SM .1W 5% 36K OHM 300-003-00 DIO SW DL4148 100V SM 140-115-00 RES TF SM .1W 5% 51K OHM 300-007-00 DIO SW 1SS244-SUB 1SS245 140-123-00 RES TF SM .1W 5% 100K OHM 301-006-00 THY 2N6507 400V 140-124-00 RES TF SM .1W 5% 120K OHM 301-007-00 DIO PWR DUAL FEP30 (D7) 140-139-00 RES TF SM .1W 5% 470K OHM 301-008-00 DIO PWR DUAL FEN30 (D8) 140-147-00 RES TF SM .1W 5% 1M OHM 301-009-00 DIO PWR 1N4004 145-318-00 RES MF SM .
M•1200/M•1400 SERVICE MANUAL PART # DESCRIPTION PART # DESCRIPTION 400-172-00 TERM SOLDER-IN 18AWG 700-058-02 MCH 4-40X1/2 SKT CLRZC 400-173-00 TERM .25 QKDS PCMT STABLE 700-059-00 HEX 5/16-18X3IN GD-5 400-210-00 TERM QDISC .250 F 18-22GA 704-001-01 PEMNUT 6-32 .038 STL 400-214-00 JACK 1/4 V PCMNT 1MM WASH 704-001-02 PEMNUT 6-32 .054 STL 410-003-00 INSL SILPAD K6 W/ADHESIVE 704-007-01 PEMNUT 4-40X.060L SS FLSH 500-022-00 SW RCKR ILLUMINATED 704-023-03 STUD 6-32X.
THE MIXER FIXER • MACKIE DESIGNS SERVICE NEWS FR Series Fuse Upgrade Model: FR Series M1200/1400, 110V only Serial #: M1200 prior to SN# AF12626 M1400 prior to SN# AH12657 Problem: Original fuse (15A) rated too low. Turn on inrush current causes fuse to open. Solution: Replace the main (F1) fuse with a 20A 250V slow blow fuse. Effective 4/28/97 Attention!: Since you will be working directly with the AC power line, great care should be taken in all aspects of the installation.
THE MIXER FIXER • MACKIE DESIGNS SERVICE NEWS FR Tywrap Mod Model: FR Series M1200/1400 Serial #: AFXXXXX to AFXXXXX Problem: The primary and secondary wires get pinched between the top cover and the fan shroud. Solution: Install a 7 ½” tywrap through the fan shroud tunnels.
FR series Amplifier ribbon replacement instructions (NEW! IMPROVED! July 2000)* Models affected: FR series M1200, M1400, M1400i M1200: All models. M1400i: Before Serial # DA20889 and all models with “AM” prefix. M1400 and 230v versions: Before Serial # DB12700 and all models with “AH” prefix. Add this as part of your normal repair procedures. Note: This bulletin replaces all previous ribbon bulletins. Symptom: Ch.
THE MACKIE FIXER MACKIE DESIGNS SERVICE NEWS Procedure continued. Input board work: If the two ribbon cables are soldered to the input board, follow steps 7 to 11. If not, then go to step 12. 7. Remove the metal shield plate and insulator sheet from the back of the input board. 8. Carefully unsolder the ribbon cable headers from J16 and J11. Discard part# 040-033-03, 4 inch ribbon cable. Discard part# 040-033-02, 18 inch ribbon cable. 9.
M•1200/M•1400 INPUT PCB 23 055-079-00 REV-D
M•1200/M•1400 INPUT PCB 24 055-079-00 REV-D
M•1200/M•1400 DISPLAY PCB 25 055-080-00 REV-A
M•1200/M•1400 DISPLAY PCB 26 055-080-00 REV-A
M•1200/M•1400 MAIN PCB 27 055-081-00 REV-D
M•1200/M•1400 MAIN PCB 28 055-081-00 REV-D
M•1200/M•1400 MAIN PCB 29 055-081-00 REV-D
M•1200/M•1400 MAIN PCB 30 055-081-00 REV-D
M•1200/M•1400 SOFT START PCB 31 055-162-00 REV-A
M•1200/M•1400 SOFT START PCB 32 055-162-00 REV-A
