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MPX 110

24 bit

Dual Channel Processor

Service
Manual

Summary of Contents for MPX 110

Page 1: ...MPX 110 24 bit Dual Channel Processor Service Manual ...

Page 2: ...intenance Instructions in this accompanying literature Notice This equipment generates and uses radio frequency energy and if not installed and used properly that is in strict accordance with the manufacturer s instructions may cause interference to radio and television reception It has been type tested and found to comply with the limits for a Class B computing device in accordance with the speci...

Page 3: ...or polarization of the unit s power cord Not applicable in Canada Power Cord Protection Route power supply cords so that they are not likely to be walked on or pinched by items placed on or against them paying particular attention to cords at plugs convenience receptacles and the point at which they exit from the unit Nonuse Periods Unplug the power cord of the unit from the outlet when the unit i...

Page 4: ...GEROUS PROCEDURE WARNINGS Warnings such as the example below precede potentially dangerous procedures throughout this manual Instructions contained in the warnings must be followed WARNING Dangerous voltages capable of causing death are present in this instrument Use extreme caution when handling testing and adjusting SAFETY SYMBOLS General definitions of safety symbols used on equipment or in man...

Page 5: ...st 4 2 listening test 4 3 Effects listening test 4 3 shock test 4 3 Audio Performance 4 3 setup 4 3 gain test 4 4 signal to noise test 4 4 thd n 4 4 frequency response test 4 4 Lexicon Audio Precision ATE Summary 4 5 Chapter 5 Troubleshooting 5 1 Diagnostics 5 1 Introduction 5 1 DIAGNOSTICS TEST DESCRIPTIONS 5 1 Power On Diagnostics 5 1 Diagnostic Failures 5 2 ROM Checksum Test 1 5 2 SRAM Test 2 5...

Page 6: ...gle ended to differential converter 6 2 AK4528 CODEC 6 2 Differential to Single Ended Output Amplifiers 6 3 Sheet 3 6 3 L3 Initialization 6 3 Audio Memory 6 4 Master Clock Generator 6 4 I O 6 4 SEEPROM 6 4 Z80 Memory Management 6 5 Clocks 6 5 DSP 6 5 Z80 RESET 6 5 Sheet 5 6 6 Encoders 6 6 Sheet 6 6 6 Control Input IAD 6 6 Sheet 7 6 6 Footswitch 6 6 LED Switch Matrix 6 6 Sheet 8 6 7 Power Fail Rese...

Page 7: ...T EQUIPMENT The following is a minimum suggested equipment list required to perform the proof of performance tests Digital Volt Meter Low Distortion Sine Wave Audio Oscillator Distortion Analyzer and Level Meter with single ended or balanced input switchable 30kHz high pass filer or audio bandpass 20 20kHz filter Stereo Headphone Amplifier 2 Audio cables unbalanced and shielded with phone plugs on...

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Page 9: ...o equipment will be accepted without 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 All shipments must be well packed using the original packing materials if pos...

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Page 11: ...20Hz 20kHz unweighted Levels 8dBu typical Resolution 24 Bit Frequency Response Wet Dry 20Hz 20kHz 1dB Crosstalk 45dB THD 0 05 20Hz 20kHz Digital Audio Interface Output Connectors Coaxial RCA type 24 bit Digital S PDIF always active Sample Rates 44 1kHz Internal Audio Data Path DSP 24 bit Footswitch Tip Ring Sleeve phone jack for Bypass and Tap optional System Specifications Power Requirements 9VAC...

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Page 13: ...UP 1 Connect the 9VAC adapter provided with the MPX 110 between the isolated variable output of the Variac and the MPX 110 rear panel Power connector 2 Verify that AC current draw is 0 1 Amps On normal power up the MPX 110 will run the following Diagnostic Tests This Diagnostic Test sequence is displayed on the front panel LEDs for trouble shooting purposes If any of the red Clip LEDs remain lit a...

Page 14: ...tton Verify that its LED is on Release Store and verify that the LED turns off Releasing Store also exits the test series and should cause both of the green Level LEDs to turn on ACD POT TEST Note During the ADC Pot Test each potentiometer must be varied over its entire range from fully counter clockwise to fully clockwise and back to fully counter clockwise within 5 seconds Otherwise the test wil...

Page 15: ...ct Lvl Bal and Adjust knobs fully clockwise 9 Put on headphones then set the headphone amplifier volume to a comfortable listening level 10 Individually adjust the MPX 110 Input and Output knobs over their entire range and verify that no pops clicks or scratchiness is heard EFFECTS LISTENING TEST 1 Turn VARIATION to 14 and press Store to return to normal operating mode 2 Verify that the processed ...

Page 16: ...t 6 Repeat the test verifying the levels at the Left output THD N This test verifies THD N through the MPX 110 signal path 1 Apply a 1kHz signal at 220mV to the MPX 110 left input 2 Adjust the scale on the distortion analyzer to measure THD N 3 Verify a distortion level 0 05 THD N at the Left output 4 Connect the oscillator output to the MPX 110 right input 5 Connect the analyzer input to the MPX ...

Page 17: ... Freq Imp Unbal Float Level Reading Upper Lower Filter Imp Band Rate a again 0dBu 0dBu 997 25 Ohm Unbal Float AMPL dBu 8 00 9 56 6 44 Off 100k 10 500k 44 1kHz a afreql 11dBu 11dBu 20 20K 25 Ohm Unbal Float AMPL dBr 0 00 1 06 1 06 Off 100k 10 500k 44 1kHz a afreqr 11dBu 11dBu 20 20K 25 Ohm Unbal Float AMPL dBr 0 00 1 06 1 06 Off 100k 10 500k 44 1kHz a axtalk 11dBu 11dBu 20 20K 25 Ohm Unbal Float XT...

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Page 19: ...iagnostic tests have been designed to take less than 10 seconds During the execution of the Power On Diagnostics the CPU wherever possible will display a test code on the EDIT BYPASS STORE TAP LED s prior to the execution of the test provided the LED s are functioning properly Throughout this document Edit Bypass Store and Tap LED s will be referred to as the Binary LED s These LED s are used to d...

Page 20: ...B LSB LED Off O 0 LED On l 1 Figure 1 This figure shows an example of the Binary LED s Failure Code 3 0011 This code indicates that the Lexichip3 WCS Test has failed ROM CHECKSUM TEST 1 The ROM checksum is a byte size value that is stored in the last location of Bank 0 The test adds the contents of the entire ROM including the Checksum byte The result should equal zero 8 bit value Before the test ...

Page 21: ...cuted a test code will be displayed on the Binary LED s The code is Edit Bypass Store Tap O O O l MSB LSB If a failure occurs the Clip red headroom LED s will be turned on in addition to the binary code If the BYPASS button is pressed the failure is ignored and the next test will be executed If the TAP button is pressed the CPU will attempt to go into a mode where it can execute the test continuou...

Page 22: ... This test will read each byte in the User Register portion of the EEPROM and add them together to calculate a checksum This value is compared with the checksum value stored in the EEPROM itself This checksum will be recalculated each time a register is stored The test will also verify that the EEPROM has been initialized properly This is done by storing the software version of the EPROM in the fi...

Page 23: ...require operator interaction and judgment Doesn t generate any error messages 3 This test requires operator interaction and judgment Generates an error message The Extended Diagnostics will be invoked by pressing holding the BYPASS button while powering on the unit When the L R Level green LED s are lit release the BYPASS button After the BYPASS button is released the Binary LED s EDIT BYPASS STOR...

Page 24: ...at resides in the power up diagnostics It was included in the Extended Diagnostics for troubleshooting purposes The ROM checksum which is a byte size value will be located as the last location of Bank 0 The test will add the contents of the entire ROM including the Checksum byte The result should equal zero 8 bit value When selected the Binary LED s will read the following Edit Bypass Store Tap O ...

Page 25: ...e L R Level green LED s will light If the test failed the L R Clip red LED s will light To run the test again press the STORE button To run the test continuously press the TAP button To stop the test from running continuously press the STORE button LEXICHIP3 WCS TEST 3 This is the same test that resides in the power on diagnostics It was included in the Extended Diagnostics for troubleshooting pur...

Page 26: ...s too short and less than 19 interrupts means it s too long When selected the Binary LED s will read the following Edit Bypass Store Tap O O O l MSB LSB Pressing the STORE button will execute the test 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 If the test ...

Page 27: ...e display will read the following Edit Bypass Store Tap O O O l MSB LSB Pressing the STORE button will execute the test When the test is executed the Left Level green LED will be lit and all Front Panel LED s will be turned off IMPORTANT The Encoder Switch LED Test MUST be performed in the proper sequence The Encoder portion of the test MUST be performed first before any Switch or LED testing can ...

Page 28: ... 1 1 0 Pitch Reverb 15 1 1 1 1 Chorus Reverb 16 0 0 0 0 Table 2 Footswitches When the left footswitch labeled Ring is pressed the left Level green LED will light The remaining LED s will be off When the left footswitch is released the left Level green LED will go off and the remaining LED s will be off as well When the right footswitch labeled Tip is pressed the right Level green LED will light Th...

Page 29: ...DC circuitry during the sweep will be analyzed and confirm that the circuit is accurately reporting the data to the Lexichip3 When the CCW CW CCW sweep has been completed successfully the test will display a Pass Fail or Timeout status on the headroom L R Level Clip red LED s When an ADC Pot is being tested the ADC Pot must be swept over its entire CCW CW CCW range within five seconds Otherwise af...

Page 30: ...FECTS LVL BAL and ADJUST pots have all been tested the headroom LED s will display the pass fail status of the test The L R Level green LED s will be lit to indicate the test has passed or the L R Clip red LED s will be lit to indicate the test has failed EEPROM CHECKSUM 8 This is the same test that resides in the power on diagnostics It was included in the Extended Diagnostics for troubleshooting...

Page 31: ...light To run the test again press the STORE button To run the test continuously press the TAP button To stop the test from running continuously press the STORE button 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 Using the A...

Page 32: ...d to a position on the PROGRAM Encoder When a position is selected its assigned LED will light There s also a position where all the LED s will light and a position where all LED s are off When the test is executed the VARIATION Encoder BYPASS TAP ADC Pots and footswitches 2 are inactive LEXICHIP3 EXTERNAL DRAM TEST 11 The DRAM test is a modified checksum test executed by the Lexichip3 and is desi...

Page 33: ...AM 1 0 1 1 When selected the Binary LED s will read the following Edit Bypass Store Tap O O O l MSB LSB Pressing the STORE button will execute the test When the test is executed the remaining buttons encoders ADC Pots and footswitches 2 are inactive During the execution of the Diagnostics in the Burn In loop the appropriate test code will be displayed on the binary LED s This code will be sent to ...

Page 34: ...d the Binary LED s will read the following Edit Bypass Store Tap O O O l MSB LSB Pressing the STORE button will execute the test When the selection is executed the remaining buttons encoders ADC Pots and footswitches 2 are inactive and the MPX 110 will exit Extended Diagnostic Mode and enter normal operating mode INITIALIZE 15 This selection will initialize all of the MPX 110 system parameters to ...

Page 35: ...Replace the nut and washer on one potentiometer at each end and hand tighten 4 Replace the remaining potentiometer nuts and washers Check for alignment then tighten all nuts Do not overtighten 5 Replace the cover being careful to align the jacks and power connector with the holes in the rear of the cover 6 Replace the seven 7 plastic nuts on the jacks Be careful not to overtighten 7 Replace the se...

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Page 37: ...o maintain a high input impedance provide unity gain at low frequencies and pre emphasis R88 R89 C89 and R101 R102 C101 are feedback networks around U21 and U23 respectively They form a high pass shelf for pre emphasis It is a 10 dB shelf starting at 3 kHz and ending at 9 kHz This is 15 50uS curve with matching de emphasis on the output The pre de emphasis improves the SNR of the unit Capacitors C...

Page 38: ...83 for the left channel and R95 R96 for the right and then AC coupled via C86 C87 and C96 C97 respectively Each phase of the differential signal pairs are then DC biased via the resistors R80 R81 and R93 R94 This DC bias of 2 94V is provided by a resistive divider comprised of R78 and R79 while C82 and C83 de couple this bias voltage to remove ripple and noise Because the CODEC samples the input a...

Page 39: ...ak This output signal is centered on 2 5V Both sections of dual op amp U20 are configured as unity gain second order low pass filters with an Fc 93 2kHz These filters provide summing of the differential signals for each channel into single ended signals R70 R72 R76 C77 C79 comprise the low pass filter for the left channel OUT_LEFT while R61 R64 R68 C70 C72 form the low pass filter for the right ch...

Page 40: ...wn the edge rates of these two signals The remaining bus signals LEX_A 2 9 are less active and therefore do not require edge rate reduction R94 R96 through R98 R102 R105 and R106 are set to 0 ohms Control signals CAS RAS and WE require edge rate reduction due to their high level of activity Therefore R95 R103 and R104 are 180 ohms MASTER CLOCK GENERATOR Y1 C76 C77 and R91 comprise the master clock...

Page 41: ...P function will add historical samples from the taps to current samples according to the algorithm for the effect The combined samples Sheet 4 The Z80 U8 ROM U4 SRAM U5 incoming encoder buffer U9 and outgoing latch U2 represent the MPX110 microprocessor control circuits The Z80 and the L3 interact regularly to control the processing For example when the Z80 passes data to the memory map address fo...

Page 42: ...itor voltage exceeds the pot voltage the muxed comparator output goes low This produces a high level interrupt to the Z80 which disables the timer At its convenience the Z80 reads the timer and derives the voltage on the pot R44 sets input voltage range from 0 3V This voltage is also the calibration voltage for the IAD it will guaranty the pots full range will be used regardless of fluctuation in ...

Page 43: ...rs C6 C50 C53 The 5VUNREG supply is monitored by the reset circuit for power up and power fail conditions Voltage regulation is handled by three TO 220 packaged ICs 5VD digital circuits U1 LM2940 5VA analog circuits U15 LM2940 5VA analog circuits U16 MC7905 Current limiting and short circuit protection are incorporated into the internal circuitry of these ICs The MPX 110 power supply also provides...

Page 44: ...he 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 S PDIF signal which increases jitter D13 helps protect from over voltage or static shock ...

Page 45: ...OHM 1 00 R44 203 10581 RESSM RO 1 1 10W 3 32K OHM 1 00 R78 203 10583 RESSM RO 1 1 10W 10 0K OHM 2 00 R3 41 203 10840 RESSM RO 1 1 10W 750 OHM 2 00 R89 102 203 10894 RESSM RO 1 1 10W 340 OHM 4 00 R82 83 95 96 203 10895 RESSM RO 1 1 10W 681 OHM 1 00 R2 203 10896 RESSM RO 1 1 10W 1 00K OHM 1 00 R1 203 11075 RESSM RO 1 1 10W 95 3 OHM 1 00 R29 203 11079 RESSM RO 1 1 10W 715 OHM 2 00 R30 31 203 11083 RE...

Page 46: ...11573 ICSM LIN NJM4580 DUALOPAMP SOP 4 00 U20 23 340 11576 ICSM LIN 7905 5V REG TO263 1 00 U16 340 11948 ICSM LIN LM339 QUAD COMP SOIC 1 00 U14 340 12849 ICSM LIN LM2940 5V REG TO263 2 00 U1 15 346 10508 ICSM SS SWITCH 74HC4053 SOIC 2 00 U13 17 350 10545 ICSM SRAM 8KX8 80NS SOIC 50uA 1 00 U5 350 12637 ICSM DRAM 1MX16 70NS SOJ 1 00 U10 350 14158 ICSM EEPROM 24C32 32K SER SOIC 1 00 U12 350 14759 ICS...

Page 47: ... 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 06 01 02 730 11670 INSERT FOAM ENDCAP 1UX4 2 00 730 14964 BOX DSPLY 24X7X4 MPX110 1 00 750 14967 CD LIT MULTI LANG MPX110 1 00 MPX110 TRANSFORMER OPTIONS 470 12754 XFORMER PLUG IN 120V 9VAC 1 9A 1 00 470 12755 XFO...

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Page 49: ...Lexicon 8 1 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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