Samsung ML-6050, Service Manual, Page: 6 / 140

Reference Information
3-2
Samsung Electronics
Abbr Definition Abbr Definition
BIOS
BPS
CMOS
CPU
DCU
DMA
DMAC
DOS
DPI
DRAM
DVM
EEPROM
ICU
Basic Input/Output System
Bits Per Second
Complementary Metal Oxide
Semiconductor
Central Processing Unit
Diagnostic Control Unit
Direct Memory Access or
Dynamic Memory Access
Direct Memory Access Controller
Disk Operating System
Dots Per Inch (resolution)
Dynamic Random Access Memory
Digital Voltmeter
Electronically Erasable
Programmable Read Only Memory
Image Control Unit
NC
PCB
PCU
PLCC
PPM
PQFP
PWM
QFP
RAM
ROM
SCC
SMPS
SOP
THV
TS
VCU
No Connection
Printed Circuit Board
Printed Control Unit
Plastic Leaded Chip Carrier
Page Per Minute
Plastic Quad Flat Package
Pulse Width Modulation
Quad Flat Package
Random Access Memory
Read Only Memory
Serial Communications Controller
Switching Mode Power Supply
Small Outline Package
Transfer High Voltage
Tri-State
Video Control Unit
3-2. Chip Replacement (SMD)
3-2-1. Precautions for Chip Replacement
1. Do not directly touch any portion of the part with
the soldering iron. ICs, especially TSOPs, are easily
damaged by heat.
2. Use care with the soldering iron tip and avoid
rapidly heating parts. Some parts can be damaged
by sudden heating. Preheat the part at about 100
o
C
for several minutes before installing it.
3. Use a soldering tip temperature of about 240
o
C.
For larger parts, use a slightly higher temperature
(about 280
o
C).
4. The thin (0.3mm) solder for miniature parts does
not contain adequate flux. Supplementary flux is
thus needed in most cases.
Computer, OA and A/V systems are manufactured
using flux which can be cleaned by water. When
you replace the part or when troubleshooting, use
proper flux and solder which can be cleaned by
water.
Improper flux may cause the soldering area to cor-
rode and may cause a fatal system error.
5. Use care not to damage the circuit pattern, especial-
ly when desoldering. Because of the many pins,
cleanliness of the pattern is extremely important
after removing an IC.
6. Use care to avoid solder bridges. Remove any
bridges that occur.
7. Position the part carefully. This also affects the sol-
dering operation. Be very precise in positioning the
IC. Soldering opposite pins first holds the IC in
place and makes soldering the other pins easier.
8. Do not reuse removed parts.
9. Clock for solder joints, especially miniature parts
with small lead.
10. A defective trimming resistor cannot be adjusted
externally. Replace with an ordinary variable resis-
tor.
11. Always inspect the work with a magnifying lens.
Check after installing cold solder joints, etc.