Larcan MXI501U User Manual

PSM20-374FB

MXi501U

TECHNICAL SERVICE MANUAL

LARCAN INC.
228 AMBASSADOR DRIVE
MISSISSAUGA, ONTARIO
CANADA L5T 2J2
PHONE: [phone]
FAX: [phone]
EMAIL: [e-mail]

PSM20-374FB
September 2010

MXI501U TECHNICAL SERVICE MANUAL

CONTENTS
PSM20-374FB MXi501U TECHNICAL SERVICE MANUAL

1 MXI501U AMPLIFIER INTRODUCTION ............................................................................................................. 1

2 SAFETY NOTICES .................................................................................................................................................... 2

2.1 BERYLLIUM OXIDE WARNING ........................................................................................................................................ 2

2.2 OTHER TOXIC MATERIALS ............................................................................................................................................. 2

2.3 DANGEROUS VOLTAGES ................................................................................................................................................. 2

2.3.1 Switch to Safety .................................................................................................................................................... 3

3 LARCAN PARTS, ASSEMBLIES, ASSEMBLY DRAWINGS AND SCHEMATIC NUMBERS ..................... 5

3.1 VENDOR STANDARD PART NUMBERS ............................................................................................................................ 5

3.2 LARCAN NUMBERS FOR PARTS, ASSEMBLIES AND DOCUMENTATION ......................................................................... 5

3.3 LEADED RESISTORS ........................................................................................................................................................ 6

3.4 SURFACE MOUNT RESISTORS 1/4W AND LESS ............................................................................................................... 6

3.5 SURFACE MOUNT CAPACITORS ...................................................................................................................................... 7

3.6 PARTS LISTS ................................................................................................................................................................... 7

3.6.1 Production Changes ............................................................................................................................................. 7

FIGURES

FIGURE 1 MXI501U AMPLIFIER ASSEMBLY ................................................................................................................................. 1

FIGURE 2 MXI501U POWER SUPPLY ASSEMBLY .......................................................................................................................... 1

PUB07-025FB MXi501U OPERATIONS AND MAINTENANCE

1 MXI501U AMPLIFIER .................................................................................................................................................... 3

2 MXI501U AMPLIFIER HEATSINK ASSEMBLY ........................................................................................................ 4

3

MXi AMPLIFIER CONTROLLER ................................................................................................................................. 5

4 AMPLIFIER INSTALLATION AND STARTUP .......................................................................................................... 7

4.1 BEFORE APPLYING AC TO THE UNIT .............................................................................................................................. 7

4.2 APPLYING AC TO THE UNIT ........................................................................................................................................... 7

4.3 BEFORE TURNING THE AMPLIFIER ON ........................................................................................................................... 8

4.4 AMPLIFIER ON SEQUENCE ............................................................................................................................................. 8

4.4.1 Turning ON MXi Amplifier .................................................................................................................................. 9

TYPICAL DATA read on the LCD ....................................................................................................................... 9

4.4.2

5

TEST AND TROUBLESHOOTING ............................................................................................................................. 10

5.1 BENCH TEST PROCEDURES ........................................................................................................................................... 10

5.1.1 Front-End Module Bench Test Procedure ......................................................................................................... 10

5.1.2 IPA, 21B1324, Bench Test Procedure ................................................................................................................ 10

5.1.3 Driver, 21B1639, Bench Test Procedure ........................................................................................................... 11

5.1.4 PA Pallet 11A2142G1 Bench Test Procedure .................................................................................................... 11

5.2 BASIC TROUBLESHOOTING TECHNIQUES ...................................................................................................................... 12

5.2.1 No RF Output ..................................................................................................................................................... 12

5.2.2 Output Reduced to 56% ..................................................................................................................................... 12

6 MAINTENANCE ............................................................................................................................................................. 13

6.1 DAILY .......................................................................................................................................................................... 13

6.2 MONTHLY .................................................................................................................................................................... 13

6.3 SEMI-ANNUALLY AND ANNUALLY ............................................................................................................................... 13

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6.4 TRANSMITTER COOLING SYSTEM ................................................................................................................................. 13

7 SERVICE.......................................................................................................................................................................... 14

7.1 REMOVING THE FAN ARRAY ........................................................................................................................................ 14

7.2 REPLACING THE ENTIRE FAN ARRAY ........................................................................................................................... 15

7.3 REPLACING A SINGLE FAN ........................................................................................................................................... 15

8 TEST EQUIPMENT SETUP .......................................................................................................................................... 16

9 SPECIFICATIONS ......................................................................................................................................................... 17

9.1 ELECTRICAL ................................................................................................................................................................. 17

9.2 ENVIRONMENTAL ......................................................................................................................................................... 17

9.3 COOLING ...................................................................................................................................................................... 17

9.4 DIMENSIONS ................................................................................................................................................................. 17

9.5 SHIPPING WEIGHT ........................................................................................................................................................ 17

PUB07-026FB MXi501U AMPLIFIER CHASSIS

1 MXI501U AMPLIFIER .................................................................................................................................................... 1

PUB07-027FB MXi501/1002U POWER AMPLIFIER HEATSINK ASSEMBLY

POWER AMPLIFIER HEATSINK ASSEMBLY 40D2104G 1 ..................................................................................... 1

1

2 FRONT END MODULE ASSEMBLY 21B1473G1 ........................................................................................................ 2

3 IPA MODULE 21B1951G1 ............................................................................................................................................... 3

4 DRIVER MODULE 21B1639G1 ...................................................................................................................................... 5

5 PA PALLET ASSEMBLY 11A2142G1 ........................................................................................................................... 6

6 FOUR-WAY SPLITTER 21B2425G1 .............................................................................................................................. 7

7 FOUR-WAY COMBINER 21B2426G1 ........................................................................................................................... 8

PUB07-029FB MXi501/1002U EXTERNAL DIRECTIONAL COUPLER

1 MXI501/1002U EXTERNAL DIRECTIONAL COUPLER .......................................................................................... 1

PUB07-015FB MXi501/1002U POWER SUPPLY

1 MXI501/1002U POWER SUPPLY PFC2K-3212A-P6951 ............................................................................................. 1

2 POWER SUPPLY DATA SHEET REPRINT ................................................................................................................ 3

PUB07-028FB MXi501U POWER SUPPLY CHASSIS

1 MXI501U POWER SUPPLY CHASSIS .......................................................................................................................... 1

2 CURRENT SENSOR BOARD 11A2226G1..................................................................................................................... 3

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PUB06-82 Rev2 MXi CONTROL LER BOARD

1 INTRODUCTION ............................................................................................................................................................. 1

2 GENERAL OPERATIONS .............................................................................................................................................. 3

2.1 CONNECTOR AND SIGNAL DEFINITIONS ......................................................................................................................... 3

2.1.1 J1 BDM (Background Debug Mode) Connection ................................................................................................ 3

2.1.2 J2 Remote RS232 Connection .............................................................................................................................. 3

2.1.3 J3 Front Panel LCD and Touchpad ..................................................................................................................... 3

2.1.4 J4 +32 Volt DC Power Supply ............................................................................................................................. 3

2.1.5 J5 +32 Volt DC Power Supply Sensing (External) .............................................................................................. 3

2.1.6 J6 Remote Controls .............................................................................................................................................. 3

2.1.7 J7 Transmitter Switch Interface ........................................................................................................................... 4

2.1.8 J8 Fan Interface ................................................................................................................................................... 4

2.1.9 J9 External Controls ............................................................................................................................................ 4

2.1.10 J10 AGC Control ................................................................................................................................................. 4

2.1.11 J11 Aural Detector (Optional) ............................................................................................................................. 4

2.1.12 J12 Forward RF Sample ...................................................................................................................................... 4

2.1.13 J13 Reflected RF Sample ....................................................................................................... .............................. 4

2.1.14 J14 Front Panel LCD Power ............................................................................................................................... 4

2.2 JUMPER OPTIONS ............................................................................................................................................................ 4

2.2.1 BDM Slide Switch S2 ........................................................................................................................................... 4

2.3 FRONT PANEL AND CONTROL INDICATORS .................................................................................................................... 7

2.3.1 Default/Normal E5= Ext E7=Out ........................................................................................................................ 7

2.3.2 Manual Override E5= Int E7=Out ...................................................................................................................... 7

2.3.3 Remote Override E5= Ext E7=In ........................................................................................................................ 7

2.3.4 Manual and Remote Override E5= Int E7=In ..................................................................................................... 7

2.4 RF DETECTOR OPERATION ............................................................................................................................................. 8

2.5 AGC, VSWR AND CUTBACK OPERATION ...................................................................................................................... 9

2.6 INTERLOCKS ................................................................................................................................................................. 10

2.6.1 Hard Interlocks .................................................................................................................................................. 10

2.6.2 Soft Interlocks .................................................................................................................................................... 11

2.7 EXTERNAL SIGNALS AND REMOTE CONTROL ............................................................................................................... 11

2.7.1 External #1 Interlock ......................................................................................................................................... 11

2.7.2 Remote Controls (Individual) ............................................................................................................................. 12

2.7.3 Remote Interface (Serial) ................................................................................................................................... 12

2.7.4 Transmitter Switching Interface ......................................................................................................................... 12

2.7.5 External DC Power Supply ................................................................................................................................ 12

3 LCD GUI INTERFACE AND TOUCHPAD ................................................................................................................. 13

3.1 MAIN SCREEN AND TOUCHPAD OPERATIONS ............................................................................................................... 13

3.1.1 REM ................................................................................................................................................................... 14

3.1.2 AGC ................................................................................................................................................................... 14

3.1.3 ERR .................................................................................................................................................................... 14

3.1.4 LOG ................................................................................................................................................................... 14

3.1.5 AMP ................................................................................................................................................................... 15

3.1.6 P/S ...................................................................................................................................................................... 15

3.1.7 INTK .................................................................................................................................................................. 15

3.1.8 GEN ................................................................................................................................................................... 15

3.2 AMPLIFIER SCREEN ...................................................................................................................................................... 15

3.2.1 TRIP ................................................................................................................................................................... 17

3.2.2 L/O ..................................................................................................................................................................... 17

3.2.3 RF ...................................................................................................................................................................... 17

3.2.4 INTK .................................................................................................................................................................. 17

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3.2.5 PSOK ................................................................................................................................................................. 17

3.2.6 FAN1 .................................................................................................................................................................. 17

3.2.7 FAN2 .................................................................................................................................................................. 18

3.2.8 FAN3 .................................................................................................................................................................. 18

3.3 POWER SUPPLY SCREEN ............................................................................................................................................... 18

3.3.1 OK STAT ............................................................................................................................................................ 19

3.3.2 PS ON ................................................................................................................................................................ 19

3.3.3 INTK .................................................................................................................................................................. 19

3.3.4 FAN .................................................................................................................................................................... 19

3.4 INTERLOCKS SCREEN ................................................................................................................................................... 19

3.4.1 TRIP ................................................................................................................................................................... 20

3.4.2 L/O ..................................................................................................................................................................... 21

3.4.3 TEMP ................................................................................................................................................................. 21

3.4.4 PSOK ................................................................................................................................................................. 21

3.4.5 VOR .................................................................................................................................................................... 21

3.4.6 CUTB ................................................................................................................................................................. 21

3.4.7 FANS .................................................................................................................................................................. 21

3.5 REMOTE CONTROLS AND RS232 SERIAL SCREEN ........................................................................................................ 22

3.5.1 Remote ............................................................................................................................................................... 23

3.5.2 NewFmt .............................................................................................................................................................. 23

3.5.3 ExtCmd .............................................................................................................................................................. 23

3.5.4 SerCmd .............................................................................................................................................................. 23

3.5.5 Error .................................................................................................................................................................. 24

3.5.6 Logs Screen ........................................................................................................................................................ 24

3.6 GENERAL SCREEN ........................................................................................................................................................ 25

4 SETUP PROCEDURES .................................................................................................................................................. 27

4.1 RF DETECTOR .............................................................................................................................................................. 27

4.2 AGC AND CUTBACK PROTECTION ............................................................................................................................... 29

4.2.1 AGC Setup .......................................................................................................................................................... 29

4.2.2 Cutback Setup .................................................................................................................................................... 29

4.3 VSWR PROTECTION .................................................................................................................................................... 29

4.4 REMOTE CONTROL INTERFACE BAUD .......................................................................................................................... 30

4.5 POWER SUPPLY VOLTAGE AND CURRENT CALIBRATION ............................................................................................. 31

5 REMOTE CONTROL CONNECTIONS MXi TRANSMITTER ............................................................................... 32

5.1 REMOTE CONTROLS ..................................................................................................................................................... 32

5.1.1 RC_TX_On Remote Transmitter ON Control .................................................................................................... 33

5.1.2 RC_TX_Off Remote Transmitter OFF Control .................................................................................................. 33

5.1.3 RC_TX_VOR Remote Transmitter VOR Control ............................................................................................... 34

5.1.4 RC_RESET Remote RESET Control .................................................................................................................. 34

5.2 EXT1 SECONDARY EXTERNAL #1 INTERLOCK ............................................................................................................. 34

5.2.1 Status Outputs .................................................................................................................................................... 35

5.3 TELEMETRY OUTPUTS .................................................................................................................................................. 35

6 CIRCUIT DESCRIPTIONS ........................................................................................................................................... 37

6.1 MC68HC908 MICROPROCESSOR ................................................................................................................................. 37

6.2 POWER SUPPLY VOLTAGE AND CURRENT MONITORING .............................................................................................. 38

6.3 ON/OFF RELAY K1 ..................................................................................................................................................... 40

6.4 AGC, CUTBACK AND VSWR ..................................................................................................................................... 40

6.5 SPI UART ................................................................................................................................................................... 41

6.6 SPI NVPOT ................................................................................................................................................................. 42

6.7 RF DETECTOR .............................................................................................................................................................. 42

6.7.1 Circuit Description ............................................................................................................................................ 42

6.8 J12 CHANNEL – VISUAL FORWARD .............................................................................................................................. 42

6.9 J13 CHANNEL – REFLECTED ......................................................................................................................................... 43

6.10 J12 CHANNEL – AURAL FORWARD ............................................................................................................................... 44

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MXI501U TECHNICAL SERVICE MANUAL

7 ADDENDUMS ................................................................................................................................................................. 45

7.1 ADDENDUM 1– CDS51405 DISPLAY CONTROLLER ..................................................................................................... 46

7.2 ADDENDUM 2–DUAL DIGITAL POTENTIOMETER WITH EEPROM ............................................................................... 49

7.3 ADDENDUM 3–SPI/MICROWIRE-COMPATIBLE UART AND +/-15KV ESD-PROTECTED RS-232 TRANSCEIVERS WITH

INTERNAL CAPACITORS ................................................................................................................................................ 52

7.4 ADDENDUM 4–MC68HC908GTXX DATA SHEET ....................................................................................................... 55

7.5 ADDENDUM 5– CURRENT TRANSDUCER HXS 20-NP .................................................................................................. 62

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MXI501U TECHNICAL SERVICE MANUAL

1 MXI501U AMPLIFIER INTRODUCTION

This Technical Service Manual contains publications (PUBs) describing the technical details of the MXi501U
amplifier, as well as the overall operating instructions, including the bench test procedures of the amplifier stages
incorporated in this unit. It also covers the transmitter’s start-up operation, and troubleshooting, as well as basic
transmitter maintenance guidelines.

The transmitter consists of an amplifier chassis that houses the main controller and touch LCD and a power
supply chassis that houses the power supply used to power the amplifiers.

Figure 1 MXi501U Amplifier Assembly

Figure 2 MXi501U Power Supply Assembly

PSM20-374FB Sept. 2010 1 MXi501U

MXI501U TECHNICAL SERVICE MANUAL

2 SAFETY NOTICES

This section provides general guidance and information for the operation, maintenance, and service personnel
who are familiar with the hazards of working with high-powered electronic circuits. This manual does not detail all
of the safety precautions which should be observed when servicing this or any other electronic equipment.

Service by inadequately trained or inexperienced personnel can result in personal injury or death and/or
damage to the equipment.

Important: All personnel concerned with the servicing of this equipment should be thoroughly familiar with

standard first aid procedures for the treatment of electrical burns and shock, including cardio-pulmonary
resuscitation (CPR).

Use the “buddy” system, with one person performing the actual service and a colleague observing. The observer
must be familiar with the work being performed and within sight and sound of the person doing the work. The
observer should not be engaged in any other work or be otherwise distracted; he must be available instantly in
case of accident.

Always have the observer with you when you work on the transmitter.

2.1 BERYLLIUM OXIDE WARNING

Internal thermal management in certain RF devices in this equipment is accomplished through the use of
Beryllium Oxide ceramic material. Do not break open any RF power transistors, or otherwise dismantle them.
Beryllium Oxide is a hard white ceramic used as insulation for heatsinking of RF power semiconductors. Beryllium
Oxide is a poison. In case of accidental breakage of devices, do not inhale the resulting beryllium dust and

avoid getting beryllium dust in your mouth. Do not let beryllium into your blood stream through cuts or
open wounds. Seek immediate medical attention if the dust enters your body in any manner. Avoid cuts by

wearing gloves while picking up the broken pieces. Be careful – do not inhale dust while replacing or emptying
vacuum cleaner filter bags and wash your hands thoroughly afterward. Wash your hands thoroughly after
replacing RF power devices. Dispose of defective RF power devices only through approved toxic waste facilities.
Wear gloves when picking up the pieces. Wash your hands thoroughly after replacing devices . Dispose of defective
devices only through approved toxic waste facilities.

When cleaning up after an accidental breakage, remember to wear a respirator mask to avoid inhaling the dust while
replacing or emptying vacuum cleaner filter bags and to wash your hands well after servicing the vacuum cleaner. If
possible, use a wet vacuum, in which the dust gets trapped in water.

2.2 OTHER TOXIC MATERIALS

The non-metallic coverings of some coaxial cables used in this equipment are flammable and can transmit fire
when ignited. Other wire coverings are not capable of supporting combustion but any non-metallic covering when
heated sufficiently can emit dense smoke and acid gases, which can be highly toxic and often corrosive.

Solvents and glues can emit toxic vapors and can be flammable. Read and understand the directions on the
containers and ensure that they are used only in well ventilated locations.

2.3 DANGEROUS VOLTAGES

This equipment has been designed to protect operating personnel from accidental contact with dangerous voltages,
by means of shields and covers. It is extremely important that any protective covering devices be kept in plac e at all
times.

While all practical safety precautions have been adopted to safeguard personnel from possible injury, both
supervisory and operating personnel are urged to ensure that the safety rules detailed below are followed as an
established routine at all times. The following four Rules are the standard safety guidelines for working with and
around transmitters.

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Rule #1 KILL THE AC POWER BEFORE IT KILLS YOU

Under no circumstances should any person reach within the cabinets for the purpose of servicing or
adjusting the equipment without first disconnecting the AC power or without the immediate presence of
another person capable of rendering aid. The “buddy” system is encouraged for transmitter work.

Rule #2 DO NOT TAMPER WITH INTERLOCKS OR SAFETY SHIELDS

Under normal circumstances, no safety shield should be removed.

Rule #3 REMOVE PERSONAL JEWELRY WHEN WORKING ON THE EQUIPMENT

The mains AC power to this transmitter can deliver high currents capable of melting metallic tools or
personal jewelry, such as watch bands, bracelets, or rings. Accidental short circuits from such metallic
objects can cause an explosive shower of molten metal which can result in serious personal injury.

Rule #4 KNOW FIRST AID AND KEEP FIRST AID SUPPLIES AVAILABLE

Illustrated first aid instructions for the treatment of electrical shock and burns and CPR procedures should
be displayed in a prominent location adjacent to the equipment. In rendering first aid, the timeliness and
effectiveness of the treatment are vitally important to the recovery of the injured person.

Always have a colleague with you when you work on the transmitter and make sure both of you know first
aid, including cardio-pulmonary resuscitation (CPR). This is most important.

Without exception, all personnel should thoroughly familiarize themselves with the procedures involved. One
person, whose normal duties place him or her at the transmitter site often, should be given complete
responsibility and authority to ensure that first aid supplies are kept onsite and maintained. Prominently
display a list of emergency phone numbers. This list should include the numbers of the nearest police,
ambulance, hospital, doctor, fire department, paramedics, poison control center, public works (roads)
department, and the utility (power and phone) companies.

Do not try to work on the transmitter if you are tired or drowsy; you could make a fatal error in judgment.

2.3.1 Switch to Safety

Here are some safety suggestions, based partially on the knowledge of experts familiar with high-powered tubed
equipment, and partially on the procedures used at a typical utility company and at a company which makes and
tests high voltage devices. A few of these suggestions apply primarily to factory environments and require some
modification to be applied in transmitter settings.

Our thanks to the Varian Corporation for sharing its "Electrical Safety Training Program" notes. Our thanks also to
Ontario Hydro for its information booklets dealing with high voltage.

Have in place a comprehensive safety program, with defined procedures. Know First Aid and CPR.
Use the “buddy” system, with one person performing the actual service and a colleague observing. The observer

must be familiar with the work being performed and within sight and sound of the person doing the work. The
observer should not be engaged in any other work or be otherwise distracted; he must be available instantly in
case of accident. Always have the observer with you when you work on the transmitter.

Pay attention to emergency communications requirements. This could even include a voice channel on the STL
so that constant communication with the studio can be maintained. Headset-equipped phones connected on this
voice channel should be installed in locations near hazardous areas or everyone on site should carry fully
charged cell phones. When you are administering CPR, you might not be able to leave your patient for the length
of time it could take to call paramedics, especially if phone service is poor, or lines are down, and/or you are in a
rural area without emergency telephone service (e.g., 911 in North America).

Do not defeat the interlock switches on access doors unless it is absolutely necessary and you know exactly
what you are doing.

Keep the area neat and tidy, free of any interfering conductive material and free of any sharp objects. Remember
that reaction to a shock could cause you to strike nearby objects.

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MXI501U TECHNICAL SERVICE MANUAL

Avoid wearing loose clothing and personal jewelry such as rings, watches, and chains when working near
energized circuits. Make a habit of removing all jewelry and storing it in a safe place as soon as you enter the
transmitter building.

Before beginning work, shut off all AC to the transmitter power supplies. Tag and lockout the switches.
Your safety routine must ensure that the person placing the tag and locking the switch is the only person who
removes it and reactivates the switch. You might want to include the AC to the remote control as well, if there is
any possibility that a studio worker could unknowingly activate the transmitter while you are working on it. One
way of ensuring that the lockout "placer and remover" are the same person is to issue individual padlocks to each
person on the transmitter technical staff.

You might want to include your tower contractor's rigging crew in the list of people who are allowed to use tags
and padlocks. As an alternative, Dielectric™ makes a transmission line lockout switch that is intended for riggers
to turn off and lock out any RF before climbing over the antenna to replace light bulbs, etc.

Proper grounding is vital. Make ground inspection a part of your maintenance program; someone's life could
depend on it.

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MXI501U TECHNICAL SERVICE MANUAL

3 LARCAN PARTS, ASSEMBLIES, ASSEMBLY DRAWINGS AND SCHEMATIC

NUMBERS

3.1 VENDOR STANDARD PART NUMBERS

Vendor or original manufacturer part numbers are indicated for most components.

3.2 LARCAN NUMBERS FOR PARTS, ASSEMBLIES AND DOCUMENTATION

An index of LARCAN specified numbers are used to define and specify the following:

• parts made by a manufacturer to LARCAN specification;

• an assembled unit or “group” such as a PC Board or completed cabinet;

• assembly drawings and schematics;

• standards.

Depending on the application, AutoCAD drawing or Microsoft Word document format is used.
Document numbers have the format YYZXXXXKn Rev m where:
YYZ Prefix denoting drawing size and Product type. Can be 10A, 11A, 20B, 21B, 30C, 31C, 40D, 41 D, 50E, 51 E

– describes drawing or document size, VHF or UHF application
XXXX Drawing Index number. Between 0000 to 9999.

K Refers to the type of drawing / document:

• “no suffix” for drawing of part (assembly or schematic)

• P = Part

• G = Group of parts

• A = Assembly drawing

• F = PC board fabrication films and

• S = Schematic

n Index number for drawing type. Part, group, assembly drawing or schematic next number and may be
one or more digits

Rev Revision (sometimes denoted as R or R–)
m Revision number and may be one digit or more. May contain a de cimal (e.g., Revision 3.2)
Drawings may consist of one or more sheets. Generally multiple sheets are used if one sheet is not enough to

show all necessary information. Sometimes, especially with older drawings, multiple sheets are used to show
more than one part or assembly.

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3.3 LEADED RESISTORS

Generic carbon composition resistors with leads are numbered as follows:

nnnx

3R



P

- or -



nnx

Power Rating Resistance Value * Tolerance
152 = 1/4W nn - first digits of K =10%
77 = 1/2W resistance (5, 10% tol.) J =5%
78 = 1W nnn - first digits of H =1%
79 = 2W resistance (1% tol.)

x - x10 multiplier
For values between 1Ω and 10Ω, a letter “R” will appear in the resistance value to indicate the decimal place.
For vendor leaded resistors a generic drawing describing basic specifications, but having many “parts”, will often

be used.
“3R152P5R6J” is 5.6Ω, 1/4W, ±5%
“3R152P470K” is 47Ω, 1/4W, ±10%
“3R152P1022H” is 10.2kΩ, 1/4W, ±1%
“3R152P102J” is 1kΩ, 1/4W, ±5%

3.4 SURFACE MOUNT RESISTORS 1/4W AND LESS

There is no specified recommended supplier of these parts. The Philips numbering system is employed with the
following parameters/designations (example follows):

9C

SIZE LxW POWER

nn=first 2 digits
x=multiplier

nnnx tolerance<5%
nnn=first 3 digits

nRnx or nnRnx or nRnnx
R inserted as decimal point

0000 - four zeros for jumper

 

RATING

0603=1.6x08mm 1 = 1/16W

0805=2x1.25mm 2 = 1/10W

1206=3.2x1.6mm 2 = 1/8W

(1% tol.)
3 =1/4W
(5% tol.)

A nnnx

RESISTANCE VALUE TOLERANCE TEMP COEF

nnx tolerance>=5%

x=multiplier

where required

 

D=0.5% C=50ppm/°C

F=1% K=100ppm/°C

J=5% L=200ppm/°C

M=300ppm/°C

The pairs of parameters enclosed in boxes are normally mutually selected; for example, a resistor having 1%
tolerance normally is selected as having a temperature coefficient of 100ppm/°C.

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Example: 9C08052A1001FK
(Size 0805, Power Rating 1/10W, Resistance 1kohm, Tolerance 1%, Temperature

Coefficient 100ppm/°C)

3.5 SURFACE MOUNT CAPACITORS

There is no specifically recommended supplier of these parts. The part numbering system being used is based on
a Philips (now Yageo/Phycomp) numbering system with the following parameters/designations (example follows):

 

SIZE LxW DIELECTRIC

0603=1.6x08mm CG = NPO nn =first 2 digits B=0.10pF 7=16VDC B=Ni/Sn
0805=2x1.25mm 2R = X7R
1206=3.2x1.6mm 2F = Y5V * x =multiplier as

9=x0.1
0=x1
1=x10
2=x100
3=x1000
4=x10000
5=x100000
* (infrequent use)

MATERIAL

2E = Z5U *

shown below
8=x0.01

Nnx

CAPACITANCE

VALUE

(in Pico farads)

C=0.25pF 8=25VDC
D=0.50pF 9=50 VDC

F=1% 0=100VDC
G=2% B=200VDC
J=5% D=500VDC
K=10%
M=20%

  

TOLERANCE VOLTAGE

RATING

TERMINATION

A=Ag/Pd
C=Ni/Sn-Pb

e.g., 0805CG102J9B
SIZE =0805
DIELECTRIC MATERIAL =NPO
VALUE =1000pF
TOLERANCE =5%
VOLTAGE RATING =50V
TERMINATION =Ni/Sn
PACKAGING =Not Specified
MARKING =None
Note that “u” appears in most cases instead of the correct symbol “μ” whenever a “micro” is required. Electr onic

parts list data, when imported by our PC publication program, allows us to substitute the correct “μ” when
checking and editing.

3.6 PARTS LISTS

Parts lists for all assemblies in the transmitter are provided on CD-ROM, in PDF format. The CD-ROM is packed
inside the transmitter cabinet for shipping.

Parts lists are generated in a hierarchical structure, beginning with major assemblies, then the subassemblies of
each major assembly, and so forth.

3.6.1 Production Changes

From time to time, it may become necessary to make changes in the equipment described in this manual. Such
changes are usually made either to provide improved performance or to accommodate component substitutions.

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MXI501U TECHNICAL SERVICE MANUAL

A revision letter or number may follow the model or group number marked on the nameplate, chassis, or circuit
board; or on the parts list (where it is an "R" followed by a dash and a number). Whenever a revision letter or
number appears, it should be quoted in any communication regarding the equipment.

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CONTENTS

1 THE MXi501U TRANSMITTER ..................................................................................................................................... 3

2 MXi501U AMPLIFIER HEATSINK ASSEMBLY ........................................................................................................ 4

3 MXi AMPLIFIER CONTROLLER ................................................................................................................................. 5

4 AMPLIFIER INSTALLATION AND STARTUP .......................................................................................................... 7

4.1 BEFORE APPLYING AC TO THE UNIT ............................................................................................................................ 7

4.2 APPLYING AC TO THE UNIT .......................................................................................................................................... 7

4.3 BEFORE TURNING THE AMPLIFIER ON ......................................................................................................................... 8

4.4 AMPLIFIER ON SEQUENCE ............................................................................................................................................ 8

4.4.1 Turning ON the MXi Transmitter ......................................................................................................................... 9

4.4.2 TYPICAL DATA read on the LCD ....................................................................................................................... 9

5 TEST AND TROUBLESHOOTING ............................................................................................................................. 10

5.1 BENCH TEST PROCEDURES ......................................................................................................................................... 10

5.1.1 Front-End Module, 21B1473, Bench Test Procedure ........................................................................................ 10

5.1.2 IPA1, 21B1324, Bench Test Procedure .............................................................................................................. 10

5.1.3 Driver Pallet, 21B1639, Bench Test Procedure ................................................................................................. 11

5.1.4 PA Pallet 11A2142G1 Bench Test Procedure .................................................................................................... 11

5.2 BASIC TROUBLESHOOTING TECHNIQUES .................................................................................................................... 12

5.2.1 No RF Output ..................................................................................................................................................... 12

5.2.2 Output Reduced to 56% ..................................................................................................................................... 12

6 MAINTENANCE ............................................................................................................................................................. 13

6.1 DAILY ......................................................................................................................................................................... 13

6.2 MONTHLY ................................................................................................................................................................... 13

6.3 SEMI-ANNUALLY AND ANNUALLY ............................................................................................................................. 13

6.4 TRANSMITTER COOLING SYSTEM ............................................................................................................................... 13

7 SERVICE.......................................................................................................................................................................... 14

7.1 REMOVING THE FAN ARRAY ....................................................................................................................................... 14

7.2 REPLACING THE ENTIRE FAN ARRAY ......................................................................................................................... 15

7.3 REPLACING A SINGLE FAN .......................................................................................................................................... 15

8 TEST EQUIPMENT SETUP .......................................................................................................................................... 16

9 SPECIFICATIONS ......................................................................................................................................................... 17

9.1 ELECTRICAL ............................................................................................................................................................... 17

9.2 ENVIRONMENTAL ....................................................................................................................................................... 17

9.3 COOLING .................................................................................................................................................................... 17

9.4 DIMENSIONS ............................................................................................................................................................... 17

9.5 SHIPPING WEIGHT ...................................................................................................................................................... 17

FIGURES

FIGURE 1 MXI501 AMPLIFIER (TOP), AND POWER SUPPLY ........................................................................................................... 3

FIGURE 2 MXI501 AMPLIFIER HEATSINK ASSEMBLY ................................................................................................................... 4

FIGURE 3 MXI CONTROLLER ........................................................................................................................................................ 5

FIGURE 4 MXI FRONT PANEL ....................................................................................................................................................... 5

FIGURE 5 MAIN MENU SCREEN .................................................................................................................................................... 5

FIGURE 6 AMPLIFIER (AMP) SUBMENU ....................................................................................................................................... 6

FIGURE 7 POWER SUPPLY (P/S) SUBMENU SCREEN ...................................................................................................................... 6

FIGURE 8 REAR PANEL SHOWING INTERLOCK CONNECTOR ......................................................................................................... 7

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FIGURE 9 MAIN MENU .................................................................................................................................................................. 8

FIGURE 10 INTERLOCKS STATUS .................................................................................................................................................. 8

FIGURE 11 TRANSMITTER ON ...................................................................................................................................................... 9

FIGURE 12 BOTTOM VIEW OF MXI ............................................................................................................................................. 14

FIGURE 13 FAN ARRAY .............................................................................................................................................................. 14

FIGURE 14 FAN ATTACHMENT TO MOUNTING PLATE ................................................................................................................. 15

FIGURE 15 TEST EQUIPMENT SETUP ........................................................................................................................................... 16

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1 THE MXi501U TRANSMITTER

The MXi501U transmitter is usually comprised of a LARCAN Modulator, a Power supply chassis, and Amplifier
chassis

The RF section of the MXi501U consists of an amplifiers chassis capable of delivering power over 500 Watts
ATSC Digital power. Its also contains the main controller board and LCD display

The power supply chassis mounted below the amplifier chassis houses a high efficiency dual output (+12VDC
and +50VDC) switching power supply. The +12VDC power supply provides power to the amplifier controller and
fans, and the +50V supplies power to the amplifier.

Figure 1 MXi501 Amplifier (top), and Power Supply

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2 MXi501U AMPLIFIER HEATSINK ASSEMBLY

Each amplifier assembly consists of a control board, a heatsink assembly that includes four cascaded broadband
amplifier stages, a 4-way splitter, a 4-way combiner, and a fuse block. The final amplifier stage (PA) comprises
five amplifiers configured in parallel. Figure 2 below shows the layout of this assembly.

Figure 2 MXi501 Amplifier Heatsink Assembly

Also mounted on the heatsink loc thermal switch that protects the
amplifier from over temperature conditions. Cooling is achieved using multiple muffin fans located under the hood
between the heatsink and the controller. This fan-array assembly is accessible from the bottom of the amplifier
assembly, and can be serviced easily by removing 3 screws.

ated near the output side of the combiner is a

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3 MXi AMPLIFIER CONTROLLER

The MXi control board (Assembly 31C1897) is a single-circuit assembly that provides all of the control functions
required for the MXi series of transmitters on a single circuit board. This board can be configured for a number of
different transmitter types, power levels, transmission standards and options.

Figure 3 MXi Controller

The MXi control board provides local front panel interface via ON/OFF and RESET buttons as well as a graphical
user interface through a front panel LCD assembly with touchpad for user commands. The board implements
controls/status/telemetry for remote control through a rear panel connector that will interface to a typical remote
control systems (such as Moseley or Gentner). An RS232 serial port is also provided to allow the operator to
access the MXi through an external computer (with the appropriate software). The MXi control board has RF
detectors for forward and reflected power and all the circuitry to support AGC/VSWR/Cutback functions. Circuitry
to control and monitor the +50V power supply is also included on this board.

Figure 4 MXi Front Panel

The user interface to the amplifier is accomplished with the front panel LCD that incorporates a touchpad as an
integral part of the unit. The LCD has the capability of displaying a variety of screens, which are selected by the
user via the touchpad. Figure 5 shows the LCD main menu, which shows the present status of the amplifier along
with the selections of submenus.

Figure 5 Main Menu Screen

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Forward (FWD) and Reflected power (RFL), AURal power, AGC and CUTBack (VSWR) control voltage, as well
as the heatsink TEMPerature (Optional) can be displayed by selecting the AMP submenu as shown in Figure 6.

Figure 6 Amplifier (AMP) Submenu

Pressing the power supply P/S submenu from the Main Menu displays the power supply voltage and current
consumption as well as its status.

Figure 7 Power Supply (P/S) Submenu Screen

For complete documentation regarding the Amplifier Controller, see the publication MXi Controller Board.

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4 AMPLIFIER INSTALLATION AND STARTUP

The MXi501U Amplifier was fully tested at LARCAN before it was delivered. Under normal circumstances, the
transmitter can be fully operational with minimal setup when turned ON. However, a good practice is to take the
“start from scratch” approach, which means that one should take precautionary measures before the amplifier is
allowed to run at full rated power. These important steps will avoid any catastrophic failures at start-up. The
procedure described is essentially the same approach taken at the factory with a new and untested transmitter.
This also applies if there is a need to completely replace a major sub-assembly in the transmitter.

4.1 BEFORE APPLYING AC TO THE UNIT

Pay careful attention to items 1 to 3 before applying AC to the amplifier. These are initial steps that must be
observed and followed for proper and safe operation of the amplifier.

1. Termination

• Ensure that the amplifier is properly terminated with a suitable load. This can be into a dummy load or into
the transmitter output system. A 50 Ohm, 1kW load with at least –20dB return loss (1.2 VSWR) is
recommended. Preferably, directional couplers with known coupling levels at the frequency of interest
should be connected at the input and output of the band-pass filter. These points are very useful in
determining absolute power levels and losses, and also for use as an RF sample for monitoring purposes.
See Figure 12 for a typical transmitter test equipment setup.

2. Interlocks

• Interlocks must be connected to the amplifier to avoid damage to the equipment and to the output section.
An Interlock is provided at the INTERLOCK terminal block located on the rear panel of the amplifier
chassis. If this interlock is open, the B+ to the amplifiers will shut down, including the cooling fans.

Figure 8 Rear Panel Showing Interlock Connector

3. Power At Minimum

• Initially, the modulator’s output should be at minimum level..

4.2 APPLYING AC TO THE UNIT

• Check that the AC MAINS going into TB1 (across L1 and L2/N) ranges from 190-264VAC. If this is so,
proceed to applying power, otherwise, investigate the source of the problem.

• Usually, once the AC is applied to TB1, the Control Power Supply turns ON and applies +12V to the MXi
controller in the amplifier chassis.

• The Power-Up screen will be displayed on the LCD, followed immediately by the MXi Main Menu.

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Figure 9 Main Menu

4.3 BEFORE TURNING THE AMPLIFIER ON

From the Main Menu, the status of the amplifier is displayed and shows if the amplifier is ready for operation.
Status legends, when lit, such as the INTK (INTERLOCK), usually signify OK conditions and that the transmitter is
ready to be switched ON.

Check that all of the following conditions are met:

1. Modulator and the up-converter, or Channel Processor are ready.

• Usually in the application of AC, the modulator goes through its warm-up sequence. When all of the red
LEDs are extinguished (not lit), it means that the modulator or up-converter is ready.

2. POWER METERING is at Zero.

• On the LCD (see Main Menu display in Figure 9), the PWR should be at 000% and the STATUS should
be TX IS OFF, NORMALLY.

3. MXi CONTROLLER is ready.

• If there were prior faults, clear them by pushing the RESET button on the power supply chassis front
panel.

4. INTERLOCKS are closed or OK.

• Interlocks and Status are OK.

Figure 10 Interlocks Status

5. AGC control is DISABLED at this time.

• Remove the AGC jumper from the control board.

6. The Amplifier is in LOCAL mode.

• Push the REM button so that it is NOT lit.

7. The TX is OFF.

• Push the Front Panel ON/OFF button so that it is NOT pushed in.

4.4 AMPLIFIER ON SEQUENCE

Upon depressing the ON button, the fans start and at the same time the +50V power supplies are enabled, thus
applying B+ to both amplifies. Since the modulator/up-converter or Channel Processor are on hot standby (RF is
always applied), the amplifiers normally produces 100% output power immediately. For first time installations, it is
recommended that the level of the modulator be set to minimum initially and then increase in steps until 100%
power is attained. This is done so that catastrophic failure is avoided. Keep in mind that in a newly installed

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transmitter that loose or bad connections in the output, as an example, is possible particularly when the output
system is not swept for proper matching or VSWR. Hence, as the power is increased, by observing the combined,
single amplifier, reflected, and reject power metering one will be able to assess if everything is in proper order.

4.4.1 Turning ON the MXi Transmitter

1. Enable amplifier LOCAL operation by pressing the REM touch butto n such that the REM legend is NOT lit.

• Push the front panel ON button.

• The MXi Amplifier should now be ON.

Figure 11 Transmitter ON

2. Monitor both +32V power supply voltages and currents on the LCD. Check that the power supplies are
operating by pressing the P/S touch button. The voltage readings should be about 30V and the currents
should be about 11A under Static condition (no RF drive).

ALLOW THE AMPLIFIER SOME WARM-UP TIME!

Only after the transmitter has been ON for approximately 15 minutes should you perform the fine
adjustments. The amplifiers must be allowed to reach their operating temperature for stable operation. The
Power Amplifiers in the MXi transmitter are equipped with thermal compensation circuits, which reduce the
output power when the temperature rises. Therefore, the operating temperature must be reached before
adjusting the RF level to its proper level, i.e. 100%. The amplifiers are also equipped with Automatic Gain
Control, primarily designed to prevent the transmitter from overpower or overdrive condition.

3. Increase the RF output by slowly turning the Modulator/Exciter or Channel Processor output level control.
Stop at about 25% output power indicated on the LCD. At this level, the current should not be more than 35
Amps.

4. If the current is not drastically higher, increase the power to 50%. Again, make note of the PS current
readings. The current should be less than 50 Amps. Proceed to the next step if this condition is met.

5. Increase the RF output to 100%. The current should be about 60A with a black video signal. Typically, with a
50% APL video signal, the current drawn is about 50A.

6. AGC SETTING: With the AGC still disabled, increase the output power to 110%, using the output level control
in the Exciter or Channel processor. Enable the AGC by inserting the AGC jumper, E16, on the control board.
Use the LOWER button on the LCD to set the power to 100%.

7. With the amplifier fully functional and adjusted to its final setting, record keeping becomes very important.
Record the current, voltage, power, etc. This data can be used as a very valuable troubleshooting tool later.
Below is typical test data pertaining to the MXi amplifier at 100% output power.

4.4.2 TYPICAL DATA read on the LCD

Amplifier
FWD 100% RFL 00.2%
AGC 1.0V CUTB 0.0V
Power Supply
PS1 VOLTS 32.0V PS1 CURR 58.0A

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5 TEST AND TROUBLESHOOTING

5.1 BENCH TEST PROCEDURES

The following procedures are test instructions for the amplifier modules comprising the MXi amplifier.

5.1.1 Front-End Module, 21B1473, Bench Test Procedure

• Connect a +32V power supply to E1.

• Apply a 0dBm (1mW) RF input to the amplifier.

• Turn RV2 fully clockwise. The front-end should have a gain of 9dB. Adjusting R25 from one extreme to

the other should vary the gain by 4dB.

• RF Mute Check: Connect a variable supply to J3-2. Gradually increase the voltage until the gain drops by

30dB or more. The applied voltage should be approximately 2.5 volts.

• Reflected Power Cutback Check: Connect the variable supply to J4-9. Increase the voltage gradually until

the gain drops by 30dB or more. The voltage should be approximately 4.0 Volts ±0.2V. This same voltage
should also be present at J3-14. J3-6 should be 4.0 volts.

• Overdrive Cutback Check: Connect the variable supply to J3-7. Increase the voltage until the gain drops

by 30dB or more. The voltage should be 7.0 volts ±0.5V. The voltage at J3-11 should be the same and
the voltage at J3-7 should be 4.0 volts.

• Set an adjustable power supply to 2.0 volts. Connect this voltage to J4-1, J4-3 and J4-5 simultaneously.

J2-6 and J3-5 should be high. Disconnecting any one or more of J4-1, 3 or 5 should cause both J2-6 and
J3-5 to go low (0V).

5.1.2 IPA1, 21B1324, Bench Test Procedure

This amplifier must be mounted on a properly sized heatsink for testing.

• Connect a suitable load to the output of the Front-End module.

• On the unit under test (IPA), set RV200 fully clockwise and set RV110 fully counter-clockwise.

• Set variable power supply to 50.0 volts and set its current limit to 1 ampere.

• Apply the +50V to the feed-through capacitor of the pre-amp shield box.

• Adjust RV3 to achieve 6.5 ±0.2 volts at the junction of R5 and RV100.

• Adjust RV200 to achieve total current draw of 500 ±20 mA.

• Check that the junction of R100 and CR100 measures between 3.5 and 5.5 volts.

• Adjust RV110 to raise total current draw to 1000 ±50 mA.

• Check that the junction of R110 and CR110 measures between 3.5 and 5.5 volts.

• Increase the power supply current limiting to 2.2 Amps.

• Increase RV3 clockwise slowly and check that the maximum current limits itself at 1.6 ±0.1 Amp but do

not allow current to go above 2 amps while performing this test.

• Reset RV3 to achieve 6.5 ±0.2 volts measured at the junction of R5 and RV100.

• Check balance of the two transistors with a voltmeter connected between the hot sides of C105 and

C115; the difference in voltage should be less than 3mV.

• Apply RF drive (max. +18 from a pre-amp) and adjust C101, C103, C111, and C113 for minimum

frequency response ripple and flat response. Gain should be a minimum of 15dB with maximum variation
less than 0.5dB over the frequency range 470MHz through 860MHz (Note: output will then be about
+33dBm or 2 Watts for an input of +18dBm, so make sure you properly protect your test equipment).

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• If roll off at the higher frequencies prevents meeting this gain-bandwidth specification, it may be

necessary to replace either C103 or C113 or both with a higher value; use variable capacitor made by
Johanson, part # 16E2320-2, which is 2.5 to 10pF.

5.1.3 Driver Pallet, 21B1639, Bench Test Procedure

• BIAS SETTING: Connect a 50-Ohm load to the output of the pallet.

• Before applying +50V to the module, adjust R12 fully clockwise. Limit the power supply current to 3.0A.

• Apply +50V to the B+ terminal. Monitor the current and adjust R12 counter clockwise (CCW) for a total

current of about 2.0A +

• Still monitoring the current, adjust R11 for the current to be at minimum, i.e. current dipping at 1.9A. This

procedure balances the current drawn by the devices, therefore, R11 should not be adjusted again unless
one or both transistors are replaced. Any bias adjustment required from here on should be done using the
overall bias adjustment, R12.

• Readjust R12 to 2.0A. This setting is an initial bias setting and may vary depending on the pallet’s

application. On analog transmitters, this adjustment is used to optimized the inter-modulation products as
well as the system linearity.

• Proceed to the next step if a network analyzer or similar equipment is available.

0.1A.

• RF SWEEP
of 470MHz to 860MHz should be 14 to 16dB.

: Adjust C7 for best frequency response. With the bias set at 2.0A, the gain in the frequency range

5.1.4 PA Pallet 11A2142G1 Bench Test Procedure

• BIAS SETTING: Connect a 50-Ohm load to the output of the pallet.

• Before applying +50V to the module, adjust R11 fully counter-clockwise. Limit the power supply current to

3.0A.

• Apply +50V to the B+ terminal. Monitor the current and adjust R11 clockwise (CW) for a total current of

2.0A + or – 0.2A.

• Proceed to the next step if a network analyzer or similar equipment is available.

• RF SWEEP

between 15 to 16dB.

: Adjust C4 for best frequency response. The gain, in the range of 470MHz to 860MHz, should be

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5.2 BASIC TROUBLESHOOTING TECHNIQUES

One of the best tools in troubleshooting is knowing what the nominal figures or typical values of the MXi amplifier
when it is at its normal performance. If a fault condition occurs, then you can compare the data taken previously
with the present conditions and come up with a reasonable conclusion about what is at fault.

The following describes some fault conditions and possible solutions.

5.2.1 No RF Output

• Check for proper power supply voltage and current

• Check for the presence of video signal to the modulator

• Ensure the modulator IF carrier switches are ON.

• Check for potential connector problems causing either no drive to a module pallet (input connector) or VSWR

(output connector) problems.

• Check the fuses on the driver stages.

5.2.2 Output Reduced to 56%

If the output is approximately 56%, a possible cause is a total loss of a pallet from the amplifiers. The MXi501
transmitter utilizes a 4-port 3dB quadrature hybrid combiner to combine the power of the four pallets on the
amplifier. For example if the amplifier pallet on input J1 produced no RF power, then half of the power at input J2
is directed into reject load R1. This occurs because 3dB hybrid coupler HY1 has only a single input and now acts
as a splitter. As a result of the reduced power at the output of HY1, some power will also be dissipated in R3. A
measurement of the current drawn by the amplifier will determine if this condition exists.

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6 MAINTENANCE

Equipment which is regularly and carefully maintained is far less likely to be subject to sudden failure than that
which is operated without regard to basic maintenance requirements. A detailed preventive maintenance program
should be established to ensure that the original efficiency and picture quality is maintained throughout the life of
the equipment. Given reasonable care and attention, the transmitter will provide efficient and reliable service for
many years.

Preventive maintenance techniques do not necessarily involve extensive dismantling of the various assemblies;
on the contrary, this practice is to be discouraged unless a valid reason exists for doing so. Preventive
maintenance is more directed at detailed physical inspection and the general observation of the equipment during
and after operation, to detect the presence of any abnormality, which, if not corrected, might result in operational
failure.

In preparing any maintenance program, the frequency and scope of the inspections must be determined and to a
great degree will be influenced by site location and the station's market parameters and consequently its hours of
operation, equipment configuration, and technical personnel deployment. For example, is the station on the air for
24 hours-a-day? Are there main/standby transmitters and are they attended or unattended?

In general, the following routines should form the basis of any maintenance program.

6.1 DAILY

At an attended site, the operator is afforded the opportunity to make frequent checks on the equipment and
thereby increase his/her familiarity with its operation. The transmitter log entries made during these checks would
include all meter readings, also any irregularity in performance or in picture quality, for later analysis. An
unattended site where equipment is operated by remote control and monitored by telemetry and a high quality off­air receiver or demodulator can also be continuously checked for performance by studio technical personnel.

6.2 MONTHLY

In addition to the normal operational tests, thorough physical inspection of every piece of equipment should be
made, with all power turned off. All surfaces should be dusted off or wiped down, terminal boards checked for
loose connections, and all components examined for any evidence of overheating. Air filter media should be
inspected and replaced if necessary. High-pressure air, not over 20psi, can be used with discretion to dislodge
dust from inaccessible places.

6.3 SEMI-ANNUALLY AND ANNUALLY

Check all external RF connections for tightness, looking specifically for any discoloration, which might indicate a
loose inner connector, flange or sleeve coupling. Test the passive RF system with a transmission test set or
network analyzer, if one is available, to identify any potential problems with the antenna or line. Inspect and clean
contacts on all switches and contactors; carefully redress contact surfaces if pitted.

Check the operation of all interlocks including patch panel, dummy load, air and thermal switches and emergency
interlocks (if applicable).

6.4 TRANSMITTER COOLING SYSTEM

All cooling fans in the transmitter are fitted with sealed bearings requiring no lubrication during the lifetime of the
motor. Access to the fan assembly is via the bottom of the transmitter.

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7 SERVICE

The MXi contains few user-serviceable parts; the modular surface-mount design makes module replacement
and/or factory repair the most efficient repair method.

The service most likely to be performed by users is the replacement of the fan array.

7.1 REMOVING THE FAN ARRAY

The MXi fan array consists of four 4” muffin-type fans which are attached to the mounting plate. The mounting
plate is secured to the bottom of the MXi chassis with five Phillips head screws.

Figure 12 Bottom View of MXi

1. Turn the MXi OFF.

2. Disconnect the AC power from the MXi.

3. Slide the MXi partially out from the mounting rack. Important: Ensure that the weight of the MXi is fully

supported.

4. With a Phillips screwdriver, remove the five mounting screws on the underside of the MXi. When

removing the last screw, be sure to hold the mounting plate in place.

5. Remove the mounting plate. The fan array is attached to the mounting plate and comes out with the plate.

Figure 13 Fan Array

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7.2 REPLACING THE ENTIRE FAN ARRAY

In the event of a fan failure, LARCAN recommends replacing the entire array, as all fans have a similar lifespan.

1. Remove the fan array as described in Section 7.1.

2. Slide the new fan array into the MXi. The power connection is aligned so that it connects when the

mounting plate is fully in place.

3. Insert and tighten the five mounting screws. Note: Screws only need to be snug; do not overtighten.

7.3 REPLACING A SINGLE FAN

1. Remove the fan array as described in Section 7.1.

2. Each of the four fans is attached to the mounting plate via two screw-and-nut assemblies. Remove the

screws and nuts and set aside.

Three-pin
wiring harness
connector

Screw-and­nut
assemblies

Figure 14 Fan Attachment to Mounting Plate

3. Disconnect the three-pin wiring harness connection by gently sliding it back with a fingernail or small

plastic tool.

4. If necessary, carefully cut and remove the zip tie holding the wires to the fan frame.

5. Remove the defective fan and replace with a known good fan of exactly the same dimensions and

specifications.

6. Re-connect the three-pin wiring harness connection.

7. Re-fasten the two screw-and-nut assemblies holding the fan to the mounting plate.

8. If necessary, replace the zip tie holding the wires to the fan frame.

9. Replace fan array into MXi as described in Section 7.1.

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9 SPECIFICATIONS

Specifications are subject to change without notice.

9.1 ELECTRICAL

AC Line Input ................................................................................................................... 190 to 264VAC, 50 to 60Hz

Power Consumption, black picture + 10% aural ............................................................................... 4000VA (typical)

9.2 ENVIRONMENTAL

Ambient Temperature ..................................................................................................... 0°C to +45°C (0°F to 113°F)

Humidity ..................................................................................................................................................... 0% to 90%

Altitude .............................................................................................................................................. 2286 m (7500 ft)

9.3 COOLING

Four 4” muffin fans per amplifier push air through the heatsinks and through the rear panel perforations.

9.4 DIMENSIONS

The Amplifiers, Power Supply, IF Modulator, and Up-converter chassis are standard 19" rack wide units.
Height

Amplifiers and Power Supply ........................................................................................................ 10.5" (6RU)

Modulator ...................................................................................................................................... 1.75” (1RU)

Total Height ..................................................................................................................................... 14” (8RU)

Depth is 31" to the back of the 2-way combiner.

9.5 SHIPPING WEIGHT

Weight

Amplifier ……………………………….……… ...................................................... Approximately 17kg (37lbs)

Power Supply ……………………………….……… .............................................. Approximately 18kg (40lbs)

Total Weight ……………………………….……… ................................................ Approximately 35kg (77lbs)

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