Ericsson LBI-31511B, Руководство по обслуживанию, Страница: 3 / 18

•
To replace TRS board:
1. Perform above procedures in reverse order.
•
To remove the PA board:
1. Remove the three retaining screws (G) securing the
PA filter cover to the main frame.
2. Remove the eight retaining screws (F) from around
the edge of the PA board.
3. Remove the two retaining screws (H) securing the
antenna connector to the main frame.
4. Loosen the retaining screw (J) securing the pass
transistor to the side of the PA chassis compartment.
5. Remove the retaining screws (K) securing the PA
transistors to the main frame.
6. Turn the radio over and remove the nut and washer
from the stud of PA transistor Q1.
7. Unsolder the two power feed through capacitors at
(L).
8. Carefully lift the PA board up off the pins extending
upward from the TRS board.
•
To replace the PA board:
1. Perform the above procedures in reverse order, being
careful to realign all interconnecting pins and
sleeves. Be sure the antenna gasket between the
antenna jack and front casting is positioned properly.
PA TRANSISTOR REPLACEMENT
•
To replace the PA RF transistors:
1. Unsolder one lead at a time with a 50 watt soldering
iron. Use a scribe or X-acto® knife to hold the lead
away from the printed circuit board until the solder
cools.
2. Remove retaining screws and lift out the transistor.
Remove any old solder from the printed circuit board
with a vacuum desoldering tool. Special care should
be taken to prevent damage to the printed circuit
board runs because part of the matching network is
included in the base and collector runs.
3. Trim the new transistor leads (if required) to the lead
length of the removed transistor. The letter "C" on
the top of the transistor also indicates the collector.
4. Apply a coat of silicon grease to the transistor mount-
ing surface. Place the transistor in the mounting hole.
Align the leads as shown on the Outline Diagram.
Then replace the transistor mounting screws using
moderate torque.
5. Solder the leads to the printed circuit pattern. Start at
the inner edge of mounting hole and solder the re-
maining length of transistor lead to the board. Use
care not to use excessive heat that causes the printed
wire board runs to lift up from the board. Check for
shorts and solder bridges before applying power.
REMOVING IC’s
Removing IC’s (and most other soldered-in components)
can be easily accomplished by using a vacuum desoldering tool.
To remove an IC, heat each lead separately on the solder side and
remove the old solder with the desoldering tool.
REPLACING CHIP COMPONENTS
Replacement of chip components should always be done
with a temperature-controlled soldering iron, using a controlled
temperature of 700
°
F (371
°
C). However, do NOT touch black
metal film of the resistors or the ceramic body of capacitors with
the soldering iron.
To Remove Chip Components
1. Grip the component with tweezers or needle nose pliers.
2. Alternately heat each end of the chip in rapid succession
until solder flows, and then remove and discard the
chip.
3. Remove excess solder with a vacuum solder extractor.
4. Carefully remove the epoxy adhesive and excess flux
to prevent damage to the printed board.
To Replace Chip Components
1. Using as little solder as possible, "tin" one end of the
component and one of the pads on the printed wiring
board.
2. Place the "tinned" end of the component on the "tinned"
pad on the board and simultaneously touch the compo-
nent and the pad with a well "tinned" soldering iron
while pressing the component down on the board.
3. Place the "tinned" soldering iron on the other end of the
component and the pad simultaneously. Apply solder
to the top of the end of the component until the solder
starts to flow. Use as little solder as possible while
getting a good joint.
4. After the component has cooled, remove all flux from
the component and printed wiring board area with
alcohol.
PROGRAMMING AND ALIGNMENT
The following procedure describes how to change the fre-
quencies in the radio EEPROM(S) for new user frequencies.
Also included is an alignment procedure guide to assist you in
aligning the radio after the frequencies have been changed. The
alignment procedure should be performed in the order given and
it must be performed prior to putting the radio back in service.
PROGRAMMING
The DELTA-S UHF Narrowband radio may be programmed
using the TQ-2310 Suitcase Programmer, the 4EX22A10 Hand
Programmer or by a Personal Computer. The procedures for
using the programmers are covered in detail in LBI-31263 (TQ-
2310) and LBI-31275 (4EX22A10). TQ-3334 provides the soft-
ware and programming instructions for programming with a PC.
When programming the radio, consideration must be given
to the individual band split for the T/R/S board. See the Program-
ming tips on the following page and the individual band splits
listed below.
NOTE
Torque #8 nut on Q1 to 6 inch pounds when replac-
ing.
NOTE
Note the position of the copper washer spacer under
transistor Q1. Be sure that this spacer is in place when
replacing the board.
Failure to solder the transistor leads as directed may
result in the generation of RF loops that could damage
the transistor r may cause low power output.
CAUTION
The RF Power Transistors used in the transmitter
contain Beryllium Oxide, a TOXIC substance. If the
ceramic or other encapsulation is opened, crushed,
broken or abraded, the dust may be hazardous if
inhaled. Use care in replacing transistors of this type.
WARNING
The CMOS Integrated Circuit de-
vices used in this equipment can be
destroyed by static discharges. Be-
fore handling one of these devices,
the serviceman should discharge
himself by touching the case of a bench test instru-
ment that has a 3-prong power cord connected to an
outlet with a known good earth ground. When solder-
ing or desoldering a CMOS device, the soldering iron
should also have a 3-prong power cord connected to
an outlet with a known good earth ground. A battery-
operated soldering iron may be used in place of the
regular soldering iron.
CAUTION
NOTE
The metallized end terminations of the parts may be
touched with the soldering iron without causing dam-
age.
LBI-31511 LBI-31511
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