User's Manual

II MAINTENANCE
10 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 For 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 two screws at the rear of the unit. These screws secure the rear bracket to the case.
Removal of these screws requires a TORX T-10 driver.
b) Remove the three side screws (one on one side, two on the other). These screws secure the front
bracket to the case. Removal of these screws requires a TORX T-9 driver.
c) Slide the case off the two-board assembly.