Ericsson Monogram Series LBI-39132, Maintenance Manual

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COMPONENT REPLACEMENT
SURFACE MOUNT COMPONENTS
Surface mount components should always be replaced using a temperature controlled soldering system. The
soldering tools may be either a temperature controlled soldering iron or a temperature controlled hot-air
soldering station. A hot-air system is recommended for the removal of components on the multi-layered
boards used in the VHF UHF Scanning radio. With either soldering system, a temperature of 700° F (371° C)
should be maintained.
The following procedures outline the removal and replacement of surface mount components. If a hot-air
soldering system is employed, see the manufacturer’s operating instructions for detailed information on the
use of your system.
•
CAUTION: Avoid applying heat to the body of any surface mount component using standard
soldering methods. Heat should be applied only to the metalized terminals of the components.
Hot-air systems do not damage the components since the heat is quickly and evenly distributed to
the external surface of the component.
•
CAUTION: The CMOS Integrated Circuit devices used in this equipment can be destroyed by static
discharges. Before handling one of these devices, service technicians should discharge themselves
by touching the case of a bench test instrument that has a 3-prong power cord connected to an
outlet with a known good earth ground. When soldering or desoldering a CMOS device, the
soldering equipment should have a known good earth ground.
SURFACE MOUNT REMOVAL
1. Grip the component with tweezers or small needle nose pliers.
2. Alternately heat the metalized terminal ends of the surface mount component with the
soldering iron. If a hot-air system is used, direct the heat to the terminals of the
component. Use extreme care with the soldering equipment to prevent damage to the
printed circuit board (PCB) and the surrounding components.
3. When the solder on all terminals is liquefied, gently remove the component. Excessive
force may cause the PCB pads to separate from the board if all solder is not completely
liquefied.
4. It may be necessary to remove excess solder using a vacuum de-soldering tool or Solder
wick . Again, use great care when de-soldering or soldering on the printed circuit boards.
It may also be necessary to remove the epoxy adhesive that was under the surface mount
component and any flux on the printed circuit board.
SURFACE MOUNT COMPONENT REPLACEMENT
1. "Tin" one terminal end of the new component and the corresponding pad of the PCB. Use
as little solder as possible.
2. Place the component on the PCB pads, observing proper orientation for capacitors,
diodes, transistors, etc.
3. Simultaneously touch the "tinned" terminal end and the "tinned" pad with the soldering
iron. Slightly press the component down on the board as the solder liquefies. Solder all
terminals, allowing the component time to cool between each application of heat. Do not
apply heat for an excessive length of time and do not use excessive solder.
MONOGRAM SERIES HANDHELD
COMPONENT REPLACEMENT
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Dec.94