SERVICING

SECTION 4 SERVICING

4.1 GENERAL

CAUTION

LTR-Net models may automatically transmit during normal operation and at power off to send registration and de-registration messages. Therefore, when a signal generator is connected to these models, be sure to use an isolation pad.

4.1.1 PERIODIC CHECKS

This transceiver should be placed on a periodic maintenance schedule to ensure that it continues to operate properly. Important checks are receiver sensitivity and transmitter frequency, deviation, and power output.

4.1.2SCHEMATIC DIAGRAMS AND COMPONENT LAYOUTS

Schematic diagrams and component layouts for the various PC boards used in this transceiver are located in the back of this manual. Included are RF and audio/logic board and interconnect schematics.

The component layouts permit easy location of components and measurement points. For the RF and audio/logic boards, a component locator guide and grid around the boards are provided to aid in locating components. All boards in this transceiver have components mounted on one side only. Therefore, most servicing can be done without removing the board from the chassis.

4.1.3 REPLACEMENT PARTS

A replacement parts list for this transceiver is located in Section 5. The main listing includes the RF board and chassis parts and another listing includes the audio/logic board parts. Parts are listed alphanumerically according to designator. For information on ordering parts, refer to Section 1.9. An exploded view of the transceiver is also included at the end of Section 6 to show the various mechanical parts.

4.1.4CONFIGURING TRANSCEIVER FOR TESTING

Multi-Net versions of this transceiver have a test mode which can be selected to perform testing. This mode is described in Section 3.13 of the manual listed in Section 1.1.1, and it permits the transceiver to be operated manually. To select the test mode, turn power on with the top two options switches pressed (to right of display).

LTR-Net and SMARTNET/SmartZone transceivers do not have a separate test mode that can be selected to perform testing. With these transceivers, temporary conventional channels should be programmed to control the transceiver manually.

If adjustments must be made to the various audio and data levels, a computer and special tune software are required. The software and procedure is different with each operating protocol. Refer to the separate manual listed in Section 1.1.1 for transceiver alignment instructions.

4.2 SURFACE MOUNTED DEVICES (SMDs)

4.2.1 SERVICING TECHNIQUES

Most of the components used in this transceiver are the surface mounted type. Since these components and the circuit traces on which they are mounted are very small in size, special care must be used when they are replaced. Multi-leaded components such as integrated circuits must usually be removed using a heat gun or some other type of heat source that heats the entire device. Take care so that nearby components are not damaged. Surface mounted components should not be reused since they may be damaged by the unsoldering process.

4.2.2 IDENTIFYING SMD RESISTORS

The value of resistors is indicated by a number printed on the resistor. A three-digit number is used to identify ±5% and ±10% resistors, and a four-digit number is used to identify ±1% resistors. Refer to the following information.

 

February 2001

4-1

Part No. 001-9800-001