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Even if you do not have the special tools (for example, a spot heater) to remove the Flat IC, with some solder (large amount), a sol-
dering iron and a cutter knife, you can easily remove the ICs that have more than 100 pins.

• PbF (: Pb free) Solder
• Soldering Iron

Tip Temperature of 700

°F ± 20°F (370°C ± 10°C)

Note: We recommend a 30 to 40 Watt soldering iron. An
expert may be able to use a 60 to 80 Watt iron where some-
one with less experience could overheat and damage the
PCB foil.

• Flux

Recommended Flux: Specific Gravity 

→ 0.82.

Type 

→ RMA (lower residue, non-cleaning type)

Note: See About Lead Free Solder (PbF: Pb free) (P.3).

1. Put plenty of solder on the IC pins so that the pins can be

completely covered.
Note:

If the IC pins are not soldered enough, you may give
pressure to the P.C. board when cutting the pins with
a cutter.

2. Make a few cuts into the joint (between the IC and its

pins) first and then cut off the pins thoroughly.

3. While the solder melts, remove it together with the IC

pins.

When you attach a new IC to the board, remove all solder
left on the land with some tools like a soldering wire. If some
solder is left at the joint on the board, the new IC will not be
attached properly.

1. Tack the flat pack IC to the PCB by temporarily soldering

two diagonally opposite pins in the correct positions on
the PCB.

Be certain each pin is located over the correct pad on the PCB.

2. Apply flux to all of the pins on the IC.

3. Being careful to not unsolder the tack points, slide the sol-

dering iron along the tips of the pins while feeding enough
solder to the tip so that it flows under the pins as they are
heated.

1. Add a small amount of solder to the bridged pins.
2. With a hot iron, use a sweeping motion along the flat part

of the pin to draw the solder from between the adjacent
pads.

11

12

Q4

1

6

2

5

3

4

Q5

1

6

2

5

3

4

DG

DG

D3.3V

D3.3V

D3.3V

DG

R6

270

R4

270

R2

270

Q3

1

2

3

4

5

Q1

1

2

3

4

5

Q2

1

2

3

4

5

LED9

CO9

1

2

3

4

LED10

CO10

1

2

3

4

LED11

CO11

1

2

3

4

LED12

CO12

1

2

3

4

LED5

CO5

1

2

3

4

LED6

CO6

1

2

3

4

LED7

CO7

1

2

3

4

LED8

CO8

1

2

3

4

LED3

CO3

1

2

3

4

LED4

CO4

1

2

3

4

LED2

CO2

1

2

3

4

LED1

CO1

1

2

3

4

RA1

1k

1
2
3
4

6

7

8

SW5

CO5

SW9

CO9

SW10

CO10

SW11

CO11

SW12

CO12

SW2

CO2

SW3

CO3

SW1

CO1

SW4

CO4

SW7

CO7

SW8

CO8

SW6

CO6

R5

68

R3

68

R1

68

LED-K6

LED-K5

LED-K4

LED-K3

LED-K2

LED-K1

LED-C1

KEY-IN1

KEY-IN3

KEY-IN2

LED-C2

LED-C3

LED-C4

R

G

G

R

G

R

G

R

R

G

G

R

G

R

G

R

G

R

G

R

G

R

G

R

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(11)

(12)

(13)

(14)

(15)

(16)

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KX-NT303X / KX-NT303X-B  : MAIN BOARD (1/2)