Lexicon MPX 110 Service Manual
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Lexicon MPX 110 Service Manual

24 bit dual channel processor
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MPX 110
24 bit
Dual Channel Processor
Service
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  • Page 1 MPX 110 24 bit Dual Channel Processor Service Manual...
  • Page 2 Copyright © 2002 Lexicon, Inc. All Rights Reserved Lexicon Inc. ● 3 Oak Park ● Bedford, MA 01730-1441 ● Tel (781) 280-0300 ● Customer Service Fax (781) 280-0499 Lexicon Part # 070-15026 Rev 0 Printed in the United States of America...

  • Page 3: Safety Suggestions

    Lexicon Safety Suggestions Read Instructions Read all safety and operating Power Cord Protection Route power supply instructions before operating the unit. cords so that they are not likely to be walked on or pinched by items placed on or against them,...
  • Page 4 Lexicon assumes no liability for the customer’s failure to comply with these requirements. GROUND THE INSTRUMENT...

  • Page 5: Table Of Contents

    Tools............................1-1 Test Equipment ........................... 1-1 Chapter 2 General Information ..............2-1 Periodic Maintenance ........................2-1 Ordering Parts..........................2-1 Returning Units to Lexicon for Service ....................2-1 Chapter 3 Specifications ................3-1 Chapter 4 Performance Verification...............4-1 Functional Tests..........................4-1 Initial Inspection........................... 4-1 power supply ..........................
  • Page 6 MPX 110 Service Manual ADC Pot Test (7) ........................5-11 EEPROM Checksum (8)......................5-12 MIDI Tests (9)..........................5-13 LED Test (10) ..........................5-14 Lexichip3 External DRAM Test (11)..................... 5-14 Burn In Loop (12)........................5-15 Audio I/O (13) ..........................5-16 Exit Diagnostics (14) ........................5-16 Initialize (15)..........................

  • Page 7: Chapter 1 Reference Documents, Required Equipment

    Audio Oscillator output • 9V AC adapter (Lexicon type or equivalent; 1.9 amp) • Lexicon Double Footswitch (Lexicon P/N 750-09277) w/15' ¼" phone plug cable configured for tip, ring & sleeve or equivalent.

  • Page 9: Chapter 2 General Information

    Return Authorization from Lexicon. If Lexicon recommends that an MPX 110 be returned for repair and you choose to return the unit to Lexicon for service, Lexicon assumes no responsibility for the unit in shipment from the customer to the factory, whether the unit is in or out of warranty.

  • Page 11: Chapter 3 Specifications

    Lexicon Chapter 3 Specifications Analog Inputs (2) Connectors: 1/4" unbalanced Impedance: 500K unbalanced for Direct Instrument input (unit detects a mono input on the right input) A/D Dynamic Range: >95dB typical, 20Hz-20kHz, unweighted Levels: -30dBu to +4dBu Resolution: 24-Bit Analog Outputs (2) Connectors: 1/4"...

  • Page 13: Chapter 4 Performance Verification

    Lexicon Chapter 4 Performance Verification This section describes procedures to verify the operation of the MPX 110 and the integrity of its analog and digital audio signal paths. Functional Tests INITIAL INSPECTION Inspect the unit for any obvious signs of physical damage. Verify that the front panel controls operate smoothly and correctly.

  • Page 14: Encoder Test

    MPX 110 Service Manual Edit Bypass Store 7. Turn VARIATION to 6 and verify that the Bypass, and Store LEDs are lit. Edit Bypass Store 8. Press Store to initiate the Encoder Test. ENCODER TEST 1. Verify that the green Level L LED is lit.

  • Page 15: Listening Test

    2. Verify that the processed audio has no audible pops, clicks, or distortion. SHOCK TEST 1. Lift each corner of the MPX 110 off the bench 4 inches (4”) then drop. To prevent damaging the unit, keep one corner of the unit touching the bench at all times.

  • Page 16: Gain Test

    6. Verify a distortion level <0.05% THD+N at the right output. FREQUENCY RESPONSE TEST This test verifies the frequency response of the MPX 110 through the signal path at 20Hz, 3kHz, 5kHz, and 20kHz. 1. Apply a 220mV signal at 1kHz with the analyzer Bandwidth filters off to the MPX 110 Right input.

  • Page 17: Lexicon Audio Precision Ate Summary

    10-500k 44.1kHz * The MPX 100 is set for analog to digital unity gain with ADSETLVL test. Note: For analog testing only, the MPX 110 can be set for analog to analog unity gain using the AASETLVL test. aasetlvl 0dBu...

  • Page 19: Chapter 5 Troubleshooting

    Upon normal power on, all of the Front Panel LED’s will be turned on for approximately 200ms, and then the MPX 110 will attempt to run the sequence of diagnostic tests listed in table 1 below. These diagnostic tests have been designed to take less than 10 seconds.

  • Page 20: Diagnostic Failures

    If the BYPASS button is pressed after a failure has occurred, the MPX 110 will attempt to continue on with the next test of the Power On Diagnostic test sequence, and the MPX 110 will attempt to do this every time the BYPASS button is pressed.

  • Page 21: Lexichip3 Wcs Test (3)

    The Interrupt Timer test will verify that the interrupt (INT/) is working and occurring at the proper intervals. The Lexichip3 will provide the MPX 110 with the interrupt (INT/) to the Z80's maskable interrupt line. The interrupt test will be run for a period of time that allows 20 interrupts to occur. A count of the interrupts is kept and compared for overshoot and undershoot.

  • Page 22: Lexichip3 Audio Data File Test (5)

    MPX 110 Service Manual LEXICHIP3 AUDIO DATA FILE TEST (5) The Audio Data File (ADF) is a fast synchronous 128-word SRAM that provides audio data buffering and storage for: external memory references, Serial I/O, and the Host-to-Lexichip data port. ADF locations also function as ARU Registers and as scratchpad memory.

  • Page 23: Extended Diagnostics

    Lexicon EXTENDED DIAGNOSTICS The following tests are available in the Extended Diagnostics: Test Test Name Binary Number LED’s Note: ROM Checksum 0 0 0 1 SRAM Test 0 0 1 0 Lexichip3 WCS 0 0 1 1 Lexichip3 Interrupt Timer...

  • Page 24: Rom Checksum Test (1)

    MPX 110 Service Manual The following tests can be run continuously by pressing the TAP button instead of the STORE button. Test Test Name Binary Number LED’s ROM Checksum 0 0 0 1 SRAM Test 0 0 1 0 Lexichip3 WCS...

  • Page 25: Sram Test (2)

    Lexicon SRAM TEST (2) The SRAM Test performed during the Extended Diagnostics is a non-destructive test. The non-destructive test will test one memory location at a time, saving the contents from the location being tested into a register, and then restoring the value when it's done. The entire contents of the SRAM is tested by writing 00 hex (00000000 binary), and verified by reading the same value back from each memory location.

  • Page 26: Lexichip3 Interrupt Timer Test (4)

    The Interrupt test will verify that the interrupt (ZINT/) is working and occurring at the proper intervals. The Lexichip3 will provide MPX 110 with the interrupt (ZINT/) to the Z80's maskable interrupt line. The interrupt test will run for a period of time that allows 20 interrupts to occur. A count of the interrupts is kept and compared for overshoot and undershoot.

  • Page 27: Encoder/Switch/Led Test (6)

    Lexicon File is working properly. When selected, the Binary LED’s will read the following: Edit Bypass Store Pressing the TAP button will run the test continuously The remaining buttons, encoders, ADC Pots and footswitches (2) are inactive. When the test is executed, all Front Panel LED’s will go off.
  • Page 28 MPX 110 Service Manual If the VARIATION Encoder fails, the Left Clip (red) LED will light. Once the VARIATION Encoder has passed, the Right Level (green) LED will be lit to indicate that the PROGRAM Encoder is being tested. When the PROGRAM Encoder has been rotated clockwise over its entire range, the Right Level (green) LED will be turned off to indicate that the PROGRAM Encoder has passed, and the Front Panel Switches and Footswitches are ready to be tested.

  • Page 29: Adc Pot Test (7)

    Lexicon Encoder Gray Scale The following table is provided as a reference for debugging encoder problems. Encoder Position Pin 1 Pin 2 Pin 3 Pin 4 Pin 5 Table 3. Note: The logic levels from the encoders are only valid when the enable (pin 5) is low.

  • Page 30: Eeprom Checksum (8)

    MPX 110 Service Manual If the MIX Pot exhibits a timeout failure, the Left Level & Clip (red) LED’s will flash about 2 times per second. EFFECTS LVL/BAL Pot Pass/Fail Status: The Right Level (green) LED will be lit to indicate when the EFFECTS LVL/BAL Pot is being tested. The remaining LED’s will be off.

  • Page 31: Midi Tests (9)

    MIDI Thru To MIDI In The MIDI Thru circuitry is tested during the ATE testing, a MIDI command is sent to the MPX 110 which sets the MIDI Out/MIDI Thru to MIDI Thru. The default setting for the MIDI Out/MIDI Thru is MIDI Out.

  • Page 32: Led Test (10)

    MPX 110 Service Manual mode or from the PC's command line. LED TEST (10) This test will verify all LED’s (8) are working. When selected, the Binary LED’s will read the following: Edit Bypass Store Pressing the STORE button will execute the test.

  • Page 33: Burn In Loop (12)

    Lexicon Edit Bypass Store Pressing the STORE button will execute the test. When the test is executed the remaining buttons, encoders, ADC Pots, and footswitches (2) are inactive, and all Front Panel LED’s will go off. If the test passed, the L & R Level (green) LED’s will light.

  • Page 34: Audio I/O (13)

    MPX 110 Service Manual AUDIO I/O (13) The Audio I/O Test will set the audio path through the MPX 110 for 100% WET signal without any effects. By using this test, the technician can eliminate major functional sections of the system when troubleshooting gain, crosstalk, frequency response, distortion and noise problems in a system.

  • Page 35: Disassembly/Reassembly

    Lexicon Disassembly/Reassembly DISASSEMBY 1. Remove six-(6) screws from the housing: three-(3) from the top, and three-(3) from the bottom. 2. Carefully remove the two end caps, swinging them out by the rack ears. 3. Remove five-(5) plastic nuts from the jacks on the rear panel.

  • Page 37: Chapter 6 Theory Of Operation

    DC blocking is incorporated by capacitors (C80 and C84) in line with the signal path. The input impedance of the MPX 110 is set by R86 and R99, 1M Ohm per channel and 500K Ohm when sum-to-mono by plugging in the Right I/P only. This allows the MPX 110 to be used with a wide variety of input sources including electric guitars.

  • Page 38: Sheet 2

    MPX 110 Service Manual for the pre-emphasis function performed before the conversion process. C59 and C62 are the +V and -V power supply bypass capacitors for U18. An impedance of 75 Ohms is developed by R52 and R53 for the left and right outputs respectively. These resistors also provide current limiting protection.

  • Page 39: Differential To Single-Ended Output Amplifiers

    (OUT_RIGHT). Both signals are referred back to page 1 to the Output and Mute circuitry. Regulated +/-5V rails power these op amps. Sheet 3 Lexichip-3B (U11) is a Lexicon proprietary audio DSP (digital signal processor) ASIC (application specific IC). The L3 has multiple functions: I/O processing, clock generation, sample management (DSP). L3 INITIALIZATION Configuration pull ups and pull downs, RP2, RP9 (10K resistor networks) set the operating mode of the Lexichip3 via the data bus ZD[7:0] when the RESET/ is released.

  • Page 40: Audio Memory

    (11.2896MHz). Pins 74 and 75 on the Lexichip3 are essentially the output and input of a CMOS buffer, respectively. The L3 is used in many Lexicon products and provides most of the I/O needed by embedded systems like the MPX-110. Looking over the L3 you will find pins designated “PIOA” and “PIOB”. These are programmable pins for I/O.

  • Page 41: Z80 Memory Management

    Lexicon EEPROM_DATA is pulled high through RP10, this signal must remain in a high logic state, this is so the EEPROM SDA signal can pull this signal to a low logic level to generate an acknowledge pulse after the reception of each byte.

  • Page 42: Encoders

    MPX 110 Service Manual During power up while RESET/ is asserted low, bringing U7 pin 1 high enables the feedback oscillator. The oscillator's output is selected as the ZCLK, and ZRST is held low by U6. When the RESET/ signal goes high, the feedback oscillator is disabled as U7 pin 1 is brought low, the ZCLK_LEXI3 clock (from the Lexichip 3) signal is selected as the ZCLK, and ZRST is controlled by ZRST_LEXI3 signal (from the Lexichip 3).

  • Page 43: Sheet 8

    5-mm/2.5-mm barrel type connector (J1), with its mating input jack located at the rear panel of MPX 110. A .1 uF capacitor, C1 is connected across the AC input to help prevent noise spikes from entering the unit. In addition, C2 (470pf) stop circuit generated RFI from radiating through the power line.
  • Page 44 MPX 110 Service Manual assuming 75 Ohm load resistor across the S/PDIF connector and a Voh out of the gates of 4.7V, which typical Voh at 6mA. C22 and C20 were added to the circuit to help meet RF compliance. However, they also band-limit the...

  • Page 45: Chapter 7 Parts List

    Lexicon Chapter 7 Parts List PART NO. DESCRIPTION EFFECTIVE INACTIVE REFERENCE MPX110 MAIN BOARD ASSEMBLY 120-14142 ADHESIVE,EPOXY,THERM COND 0.00 200-11946 POT,RTY,10KBX2,7MMFL,14,15L 3.00 R45,50,77 200-12169 POT,RTY,5K15AX2,7MMFL,14,15L 1.00 200-12184 POT,RTY,10K15AX2,7MMFL,14,15L 1.00 202-09794 RESSM,RO,0 OHM,0805 1.00 202-09795 RESSM,RO,5%,1/10W,2.2K OHM 3.00 R14,27,28 202-09871 RESSM,RO,5%,1/10W,1K OHM 3.00...

  • Page 46: Mpx110 Mechanical Assembly

    MPX 110 Service Manual 244-10423 CAP,MYL,.22uF,50V,RAD,5%,BOX 2.00 C80,84 244-14616 CAP,MYL,3300pF,100V,RAD,5%,BOX 2.00 C70,79 245-09291 CAPSM,CER,470pF,50V,COG,5% 5.00 C2,71,72,77,78 245-09876 CAPSM,CER,.01uF,50V,Z5U,20% 1.00 245-09895 CAPSM,CER,10pF,50V,COG,10% 3.00 C24,95,107 245-10416 CAPSM,CER,1000pF,50V,COG,5% 1.00 245-10561 CAPSM,CER,100pF,50V,COG,5% 7.00 C10-12,88,91,100,103 245-10562 CAPSM,CER,150pF,50V,COG,10% 6.00 C8,9,55,56,81,85 245-10976 CAPSM,CER,47pF,50V,COG,5% 1.00 245-11625 CAPSM,CER,33pF,50V,COG,5% 2.00...

  • Page 47: Mpx110 Ship/Packaging Material

    Lexicon 650-03970 POPRVT,1/8X1/8,REG PROT HD,SS 1.00 BRACKET TO PCB 700-14962 COVER,MPX110 1.00 701-11934 BRACKET,KEYSTONE,613,.147/.128 1.00 PCB TO FRONT PANEL 702-14641 PANEL,SIDE,1.71X3.93,ABS 2.00 702-14960 PANEL,FRONT,MPX110 1.00 740-09538 LABEL,S/N,CHASSIS,PRINTED 1.00 740-13573 LABEL,MFR ID,.9X.25,SILVER 1.00 MPX110 SHIP/PACKAGING MATERIAL 070-14956 GUIDE,USER,MPX110 1.00 070-14957 NOTES,ERRATA,MPX110 1.00...

  • Page 49: Schematics

    Lexicon Chapter 8 Schematics and Drawings Schematics: 060-14569 SCHEM,MAIN BD,MPX110 Drawings: COMPONENT LAYOUT, MAIN BD,MPX110 080-14958 ASSY DWG,SHIPMENT,MPX110 080-14959 ASSY DWG,CHASSIS,MPX110...
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  • Page 75 Lexicon, Inc. 3 Oak Park Bedford, MA 01730-1441 Tel: 781-280-0300 Customer Service Fax: 781-280-0499 Email: csupport@lexicon.com www.lexicon.com Lexicon Part No. 070-15026 Rev 0 Printed in U.S.A.

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