ATX Larcan MXD5U Technical & Service Manual Download Page 16

MXD5U OPERATIONS AND MAINTENANCE 

5 MAINTENANCE 

5.1 

5.2 

5.3 

5.4 

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. 

D

AILY

 

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 off-
air receiver or demodulator can also be continuously checked for performance by studio technical personnel. 

M

ONTHLY

 

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. 

S

EMI

-A

NNUALLY AND 

A

NNUALLY

 

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). 

T

RANSMITTER 

C

OOLING 

S

YSTEM

 

All cooling fans in the transmitter are fitted with sealed bearings requiring no lubrication during the lifetime of the 
motor. 

 

 

PUB09-03 Rev 0  April 16, 2009 

09-03-13 

MXD5U Operations and Maintenance 

Summary of Contents for Larcan MXD5U

Page 1: ...MXD5U AMPLIFIER TECHNICAL SERVICE MANUAL LARCAN INC 228 AMBASSADOR DRIVE MISSISSAUGA ONTARIO CANADA L5T 2J2 PHONE 905 564 9222 FAX 905 564 9244 EMAIL techservices larcan com PUB09 03 Rev 0 16 April 2009 ...

Page 2: ...S 11 4 1 1 Front End Module Bench Test Procedure 11 4 1 2 IPA1 Bench Test Procedure 11 4 1 3 Pallet 21B1751 Bench Test Procedure 11 4 2 BASIC TROUBLESHOOTING TECHNIQUES 12 4 2 1 Amplifier Completely OFF 12 4 2 2 No RF Output 12 4 2 3 Output Reduced to 25 12 5 MAINTENANCE 13 5 1 DAILY 13 5 2 MONTHLY 13 5 3 SEMI ANNUALLY AND ANNUALLY 13 5 4 TRANSMITTER COOLING SYSTEM 13 6 TEST EQUIPMENT SETUP 14 7 S...

Page 3: ...TEST EQUIPMENT SETUP 14 FIGURE 9 FRONT END AMPLIFIER MXD5U 16 FIGURE 10 IPA ASSEMBLY MXD5U 17 FIGURE 11 AMPLIFIER PALLET MXD5U 18 FIGURE 12 MXD5U CONTROL BOARD ASSEMBLY 19 PUB09 03 Rev 0 April 16 2009 09 03 ii MXi005U Operations and Maintenance ...

Page 4: ...ree cascaded broadband amplifier modules and a directional coupler Figure 1 shows the layout of this assembly Figure 1 MXD5U Amplifier Heatsink Assembly Also mounted on the heatsink is a thermal switch that protects the amplifier from over temperature conditions PUB09 03 Rev 0 April 16 2009 09 03 1 MXD5U Operations and Maintenance ...

Page 5: ... Circuitry to control and monitor the 28V power supply is also included on this board Figure 3 Front Panel 2 1 CONTROL BOARD ASSEMBLY AND JUMPER SETTINGS Figure 9 shows the assembly diagram for the control board Part No 31C1897A2 that performs all the control monitoring RF detection and communication functions There are a number of jumpers on this board that are factory set and should not be alter...

Page 6: ...ter Setting no jumper installed E8 Not installed in this assembly E9 Not installed in this assembly E10 Not installed in this assembly E11 Forward Power Sample Gain Sets either High or Low gain from the DC sample received from the RF coupler Set to obtain a voltage between 4 5 and 8V at TP2 for full power RF output Can be either in the HI or LO position depending on channel and RF coupler Typical ...

Page 7: ... the filter output calibrating to a 5W level installation and alterations of test loads are done at the filter output not transmitter RF Output PLEASE NOTE SAFETY WARNING ABOVE Connect a jumper wire across the terminals of the INT K External Interlock terminal block at the rear panel This is temporary and must be removed when tests are completed Confirm Amplifier Bias Terminate RF Out with 50R min...

Page 8: ... of two positions one labeled INT and the other position EXT When the jumper E5 is in position INT then the transmitter will ignore any ON or OFF remote controls This remote controls can either come from the serial communication program or from the external remote control connector on the rear of the transmitter chassis Please note that only the ON and OFF remote controls are disabled and the AGC ...

Page 9: ... all these remote commands are active low and require a short to ground Figure 4 Remote Command Inputs 2 4 2 Remote Telemetry Outputs There are only four remote telemetries available to the operator these being RF forward power RF reflected power AGC voltage and Cutback voltage In the table of remote signals all remote commands have a RT_ prefix The only further note on the telemetry outputs conce...

Page 10: ... collector output that comes directly from the NPN transistor outputs of the opto isolator devices The available output sink current is dependent on the opto isolator transfer ratio Generally one can expect at least 20mA of sinking current for each output listed here Because these are open collector they can be connected to maximum 30 VDC output The active true condition whether high or low will d...

Page 11: ...nsure that it is shorted out i e closed so that the transmitter is enabled to be turned ON The external1 interlock contacts are available in two separate locations The first location is on the two pin terminal block on the rear of the transmitter chassis This is the more likely and convenient place for the External1 interlock to be connected A second parallel set of contacts is located on the 15 p...

Page 12: ...oint is provided below the RF out on the front panel Its coupling is approximately 24dB and it is not calibrated for exact measurements 2 Interlocks Interlocks are employed by the amplifier to avoid damage to the equipment and to the output section For instance an internal interlock for over temperature exists to shut down the Transmitter if the temperature of the amplifier heatsink exceeds a cert...

Page 13: ... the transmitter has been ON for approximately 15 minutes should you perform fine adjustments The amplifier must be allowed to reach its operating temperature for stable and consistent operation The Power Amplifier in the transmitter is equipped with thermal compensation circuits which reduce the output power when the temperature rises Therefore the operating temperature must be reached before adj...

Page 14: ...of 300 20mA Check that the junction of R100 and CR100 measures between 3 5 and 5 5 volts Adjust RV110 to raise total current draw to 1 0A 50mA Check that the junction of R110 and CR110 measures between 3 5 and 5 5 volts Increase the power supply current limiting to 2 2A 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 abov...

Page 15: ... conclusion about what is at fault The following describes some fault conditions and possible solutions Amplifier Completely OFF The amplifier is equipped with a fused AC line filter Although it rarely happens abnormal conditions such as power surges may cause the fuse to blow Blown AC fuses will completely shutdown the amplifier In this case replacing the fuse will rectify the problem No RF Outpu...

Page 16: ... 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 off air receiver or demodulator...

Page 17: ...MXD5U OPERATIONS AND MAINTENANCE 6 TEST EQUIPMENT SETUP Figure 8 Test Equipment Setup PUB09 03 Rev 0 April 16 2009 09 03 14 MXD5U Operations and Maintenance ...

Page 18: ...AL Ambient Temperature 0 C to 45 C 0 F to 113 F Humidity 95 Altitude 3500m COOLING 1 muffin fan pulls air through the front panel and heatsink and out through the rear panel DIMENSIONS The Amplifier and Modulator chassis are standard 19 rack wide units Height Amplifier 3 5 2RU Modulator 1 75 1RU Total Height 5 25 3RU SHIPPING WEIGHT Weight Approximately 6 5kg 14lbs PUB09 03 Rev 0 April 16 2009 09 ...

Page 19: ...MXD5U OPERATIONS AND MAINTENANCE Figure 9 Front End Amplifier MXD5U PUB09 03 Rev 0 April 16 2009 09 03 16 MXD5U Operations and Maintenance ...

Page 20: ...MXD5U OPERATIONS AND MAINTENANCE Figure 10 IPA Assembly MXD5U PUB09 03 Rev 0 April 16 2009 09 03 17 MXD5U Operations and Maintenance ...

Page 21: ...MXD5U OPERATIONS AND MAINTENANCE PUB09 03 Rev 0 April 16 2009 09 03 18 MXD5U Operations and Maintenance Figure 11 Amplifier Pallet MXD5U ...

Page 22: ...MXD5U OPERATIONS AND MAINTENANCE PUB09 03 Rev 0 16 April 2009 09 13 19 MXD5U Operations and Maintenance Figure 12 MXD5U Control Board Assembly ...

Page 23: ...MXD5U OPERATIONS AND MAINTENANCE NOTES PUB09 03 Rev 0 16 April 2009 MXD5U Operations and Maintenance ...

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