Ericsson LBI-31511B, Maintenance Manual, Page: 2 / 18

TRANSMITTER ADJUSTMENT
The adjustment for the transmitter includes measuring the
forward and reflected power and adjusting the antenna length for
optimum ratio, then setting the transmitter to rated power output.
Next, measure the frequency and modulation and record these
measurements for future reference. For the complete transmitter
adjustment, refer to the Alignment Procedure (see Table of
Contents).
MAINTENANCE
PREVENTIVE MAINTENANCE
To ensure high operating efficiency and to prevent mechani-
cal and electrical failures from interrupting system operations,
routine checks should be made of all mechanical and electrical
parts at regular intervals. This preventive maintenance should
include the checks as listed in the table of Maintenance Checks.
DISASSEMBLY
•
To gain access to the unit for servicing:
1. Unlock the radio.
2. Pull down the handle.
3. Pull the radio forward and lift radio out of mounting
place -- if desired.
4. Pry up the front of top cover and lift the cover off.
5. To gain access to the bottom side, pull the radio all
the way out of the mounting frame and remove the
four mushroom shaped feet using a #30 Torx® screw-
driver.
•
To remove the TRS board:
1. Remove the bottom cover.
2. Remove the eleven retaining screws at (A) (Figure 1)
securing the circuit board to the main frame.
3. Remove two retaining screws (B) securing systems
connector J601 to front casting.
4. Unsolder the two feed through capacitor terminals
(E) on printed wire pattern.
5. Turn over the radio and remove the three retaining
screws (D) (Figure 2) securing the audio bridge am-
plifier, U601 and U602, and the 5 and 9 volt regula-
tors U702 and Q705 to the side of chassis.
6. To remove the front end shield, remove the 20 retain-
ing screws securing the shield to the front end casting
and remove.
7. To remove the synthesizer shield, remove the seven-
teen retaining screws securing the shield to the syn-
thesizer top casting.
MAINTENANCE CHECKS
INTERVAL
6 Months
As
Required
CONNECTIONS - Ground connections and connections to the voltage source should be periodically
checked for tightness. Loose or poor connections to the power source will cause excessive voltage
drops and faulty operation. When ground connections are not made directly to the battery, the
connection from the battery to vehicle chassis must be checked for low impedance. A high impedance
may cause excessive voltage drips and alternator noise problems. X
ELECTRICAL SYSTEM - Check the voltage regulator and alternator or generator periodically to
keep the electrical system within safe and economical operating limits. Overvoltage is indicated when
the battery loses water rapidly. Usage of 1 or 2 ounces of water per cell per week is acceptable for
batteries in continuous operation. A weak battery will often cause excessive noise or faulty operation. X
MECHANICAL INSPECTION - Since mobile units are subject to constant shock and vibration, check
for loose plugs, nuts, screws and parts to make sure that nothing is working loose. Be sure that all
screws are properly torqued. X
ANTENNA - The antenna, antenna base and all contacts should be kept clean and free from dirt or
corrosion. If the antennas or its base should become coated or poorly grounded, loss of radiation and
a weak signal will result. X
ALIGNMENT - The transmitter and receiver meter readings should be checked periodically, and the
alignment "touched up" when necessary. Refer to applicable Alignment Procedure and troubleshoot-
ing sheet for typical voltage readings. X
FREQUENCY CHECK - Check transmitter frequency and deviation. Normally, these checks are
made when the unit is first put into operation, after the first six months and once a year thereafter. X
Copyright© September 1985, General Electric Company
NOTE
With the top cover removed all components on the
PA and TRS board are accessible for tuning. The PA,
IF, and synthesizer/exciter covers must be removed
to expose components.
Figure 1 - Disassembly - Bottom View
Figure 2 - Disassembly - Top View
LBI-31511 LBI-31511
1