Comnet MLS II MLSH041, Руководство по обслуживанию

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LBI-38425A MAINTENANCE
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3.4 CHIP COMPONENT REPLACEMENT
Replacement of chip capacitors 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.
NOTE
The metallized end terminations of the parts may be touched with the soldering iron
without causing damage.
3.4.1 To Remove Chip Components
1. Using two soldering irons, heat each end of the chip at the same time until solder
flows and then remove and discard the chip.
2. Remove excess solder with a vacuum solder extractor.
3. Carefully remove the epoxy adhesive and excess flux to prevent damage to the
printed board.
3.4.2 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 component 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.
h
The CMOS integrated Circuit devices used in this equipment can be destroyed by static
discharges. Before handling one of these devices, the serviceman should discharge
himself 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 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.