Maintenance; Important Maintenance Information - Ritron DTX-165-0 Maintenance And Operating Manual

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MAINTENANCE

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IMPORTANT MAINTENANCE INFORMATION

Surface Mount Repair: RITRON surface mount products require special equipment and
servicing techniques. Improper servicing techniques can cause permanent damage to the printed
circuit board and/or components, which is not covered by RITRON's warranty. If you are not
completely familiar with surface mount component repair techniques, RITRON recommends that
you defer maintenance to qualified service personnel.
Precautions Handling CMOS Devices: The DTX transceiver module contains complementary
metal-oxide semiconductor (CMOS) devices, which require special handling techniques. CMOS
circuits are susceptible to damage by electrostatic or high voltage charges. Damage can be
latent, with no failure appearing until weeks or months later. For this reason, take special
precautions any time you disassemble the module. Follow the precautions below, which are even
more critical in low humidity environments.
1) Storage/transport-CMOS devices that will be stored or transported must be placed in
conductive material so that all exposed leads are shorted together. CMOS devices must not
be inserted into conventional plastic "snow" or plastic trays of the type that are being used for
other semiconductors. Conductive containers are typically gray or pink in color.
2) Grounding-All CMOS devices must be placed on a grounded bench surface. The technician
that will work on the radio/CMOS circuit must be grounded before handling the radio.
Normally, the technician wears a conductive wrist strap in series with a 100 k resistor to
ground.
3) Clothing-Do not wear nylon clothing while handling CMOS circuits.
4) Power Off-Remove power before connecting, removing, or soldering on a PC board that
contains CMOS devices.
5) Power/Voltage Transients-Do not insert or remove CMOS devices with power applied.
Check all power supplies to be used for testing CMOS devices, making sure that no voltage
transients are present.
6) Soldering-Use a soldering iron with a grounded tip for soldering CMOS circuitry.
7) Lead-Straightening Tools-When straightening CMOS leads, provide ground straps for the tool
used.
VCO Shield: The VCO shield is virtually impossible to remove without damaging either the PC
board or nearby components. The parts within the shield are low failure items; repair or
replacement should not be required unless the RF board is mishandled. If failure of a part within
the shield is deemed to have occurred, the RF board should be returned to RITRON for service or
replacement.
Unit Disassembly and Re-assembly:
1) Case Removal
a) Remove the (4) screws at the ends of each of the sides of the unit. These screws secure
the Bottom Panel to the case. Removal of these screws requires a medium Phillips
driver.
b) Remove the Bottom Panel.
2) Board Separation
Remove the (4) screws that secure the Control/Loader board to the RF Board. Remove the
two Hex Spacers next to the DB-15 Connector that secure the Control/Loader Board to the
front panel. Gently pull the two boards apart at the header/socket.