Samsung MC26AC2X Service Manual download pdf (Page 40)

5-15Samsung Electronics

5-3 PCB Inspection

5-3-1 Cautions for Part Replacement

5-3-2 Procedure

The parts should be replaced in the following procedure.

1. The human body carries much static

electricity. Before touching a part for

repair, replacement or the similar purpose,

be sure to touch a grounded metallic

portion by hand to let the static electricity

go through the metallic portion to the

earth.

Especially when handling any micro

computer or IC, carefully remove such

static electricity before touching them.

2. When repairing any part on a work bench,

be sure to place an insulative sheet on the

bench and always keep the sheet surface

neat without any metal fragments. If any

such fragment touches a part, a secondary

trouble will possibly be caused in the part.

3. Before replacing any parts, be sure to turn

off the power supply. If such replacement

is done with the power supply kept on, an

electric shock, short circuit or destruction

of a part may result.

4. During replacement or repair of a part,

carefully handle it : The printed circuit

board has fine lead wires (jumper wires)

and glass-made parts (diode) on its

substrate.

So if a circuit board is roughly handled,

such lead wires and parts will be easily

broken or damaged by bending or shock.

5. When soldering the lead wires of any new

part, be sure to polish them using an

emery paper or the like before solding

them.

Since the lead wires of any new part are

covered with an oxide film, solder cannot

adhere to the lead wires if not polished.

6. When soldering any part, care should be

exercised not to apply any high-wattage

soldering iron to the part for a long time.

Some parts are of so low a heat resistance

that they may be broken or have the

properties changed if a soldering iron is so

applied (Otherwise, the pattern may

possibly be separated and raised).

7. The heat of the soldering iron should be

transfered to the entire object to be

soldered. If the solder pieces are not well

fused due to insufficient transfer of the

heat from the soldering iron, no satisfacto-

ry electrical continuity can be assured

even if the soldered objects appear well

connected to each other.

8. The solder used should be limited to a

minimum. If excessive solder is used, it

will cause inter-pattern contact, which

may cause malfunction of the circuit.

The repair is completed.

Check the operation of the new part.

Replace it with a new part.

Detach the faulty part.

Check for any faulty part.

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