Motorola HT1250-LS+ Service Manual page 39

Maintenance
• Chip Components
Use either the RLN-4062 Hot-Air Repair Station or the Motorola 0180381B45 Repair Station for
chip component replacement. When using the 0180381B45 Repair Station, select the TJ-65 mini-
thermojet hand piece. On either unit, adjust the temperature control to 700 degrees F. (370
degrees C), and adjust the airflow to a minimum setting. Airflow can vary due to component
density.
• To remove a chip component:
• Use a hot-air hand piece and position the nozzle of the hand piece approximately 1/8" (0.3
cm) above the component to be removed.
• Begin applying the hot air. Once the solder reflows, remove the component using a pair of
tweezers.
• Using a solder wick and a soldering iron or a power desoldering station, remove the excess
solder from the pads.
• To replace a chip component using a soldering iron:
• Select the appropriate micro-tipped soldering iron and apply fresh solder to one of the sol-
der pads.
• Using a pair of tweezers, position the new chip component in place while heating the fresh
solder.
• Once solder wicks onto the new component, remove the heat from the solder.
• Heat the remaining pad with the soldering iron and apply solder until it wicks to the compo-
nent. If necessary, touch up the first side. All solder joints should be smooth and shiny.
• To replace a chip component using hot air:
• Use the hot-air hand piece and reflow the solder on the solder pads to smooth it.
• Apply a drop of solder paste flux to each pad.
• Using a pair of tweezers, position the new component in place.
• Position the hot-air hand piece approximately 1/8" (0.3 cm) above the component and begin
applying heat.
• Once the solder wicks to the component, remove the heat and inspect the repair. All joints
should be smooth and shiny.
• Shields
Removing and replacing shields will be done with the R1319A station with the temperature
control set to approximately 415°F (215°C) [445°F (230°C) maximum].
• To remove the shield:
• Place the circuit board in the R1319A holder.
• Select the proper heat focus head and attach it to the heater chimney.
• Add solder paste flux around the base of the shield.
• Position the shield under the heat-focus head.
• Lower the vacuum tip and attach it to the shield by turning on the vacuum pump.
• Lower the focus head until it is approximately 1/8" (0.3 cm) above the shield.
• Turn on the heater and wait until the shield lifts off the circuit board.
• Once the shield is off, turn off the heat, grab the part with a pair of tweezers, and turn off the
vacuum pump.
• Remove the circuit board from the R1319A circuit board holder.
• To replace the shield:
• Add solder to the shield if necessary, using a micro-tipped soldering iron.
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