Service manual

Samsung Electronics 8-10
8-5. Defective Operation
PROBLEM ITEMS TO BE CHECKED HOW TO SOLVE
LCD does not
display
(operation panel)
Cannot enter by
keys(operation
panel)
LF MOTOR does
not operate.
CR MOTOR does
not operate.
TX MOTOR does
not operate.
Paper Jam
• Powered up?
• VCC(+5v) M+4.5V?
• Is the level of U16-130(_POR) high
(more than +4V)?
• Check Main to OPE harness and
J3(main).
• Is the level of U16-153 (_RST_OUT)
high (more than +4V)?
• Is the level of U18-31 (_OPE_RST)
high (more than +4V)?
• Check control signals of U16-124,
125(OPE_TXD, OPE_RXD).
• Refer to 4-7 of “LCD does not display”.
• Check OPE key contacts.
• Check the control signals of U16-
141~145.
• Check input signals and driving output
of U1 and U2.
• Check the control signals of U16-
31~36.
• Check input signals and driving output
of U25 and U28.
• Check the operation of the document
sensor of OPE PBA.
• Check the operation of TX Motor.
➀
Check the control signals of U18-
105~110.
➁
Check input signals and driving out-
put of U23 and U24.
• Check sheet feeder and ejector.
• Check the operation of LF motor.
• Check paper exit sensor.
• Check power.(SMPS)
a
Check if the cord is connected.
b
Check each power channel. (+5V,
+11.75V, +30V)
• Check power harness.
• Check the circuit around U103.
• Replace defective parts.
• Check the state of data bus of U16.:
Replace the main PBA.
• Check the circuit around U18.
• If signals of OPE_TXD are defective,
replace the main PBA. If signals of
OPE_RXD is defective, replace OPE
PBA.(Refer to circuit explanation.
• Refer to 4-7 of “LCD does not display”.
• Replace OPE.
• If control signals are not made when the
other functions are normal, replace the
main PBA.
• If driving output is defective when input
signals are normal, replace U1 and U2.
• If control signals are not made when the
other functions are normal, replace the
main PBA.
• If driving output is defective when input
signals are normal, replace U25 and
U28.
• If defective, replace the sensor.
•
➀
If control signals are not made when
the other functions are normal, replace
the main PBA
➁
If driving output is defective when the
other functions are normal, replace
U23 and U24.
• Get rid of jammed paper.
• Refer to “LF motor does not operate.”
• If the sensor senses paper exit when it
operates normally, replace the main
PBA.