Epson LQ 1050 Technical Manual - Page 174

Unit Repair

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REV.-A 5.4 UNIT REPAIR Unit repair is comprised of three parts: ( 1 ) repair of the power supply circuit; (2) repair of the control circuit; (3) repair of the printer mechanism. This section describes (1) power supply circuit unit repair. If (2) control circuit, or (3) printer mechanism need repair, use the diagnostic tool introduced in Section 5.2. 5.4.1 Power Supply Circuit This section indicates possible causes and checkpoints for different of power supply circuit. The checkpoints include waveforms for normal operation. By referring to the checkpoints, determine the detective component and perform the proper repair. Table 5-6 has the following four columns: q Symptom: Check symptoms against those given in this column. q Cause: Check problems against the causes listed in this column. q Check Point: Use the instructions given in this column for troubleshooting. q Solution: Make repairs according to the instructions given in this column. Table 5-5. Power Supply Circuit Parts List Location IC 1A DB 1 Qlo, Q12 Q1 1 Q13 F2 F3 F4 Name NJM2355 DBF608 2SA1 450 2SC3748 2SC3746 - - - Description Pulse width modulation control Diode Bridge 100V, 6A 80V, 500mA, 600mW 60V, 10A 60V, 5A Fuse 250V, 3 15A Fuse 125V, 2A Fuse 125V, 2A 5-17

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REV.-A
5.4
UNIT REPAIR
Unit repair is comprised of three parts: ( 1 ) repair of the power supply circuit; (2) repair of the control
circuit; (3) repair of the printer mechanism.
This section describes (1) power supply circuit unit repair. If (2) control circuit, or (3) printer mechanism
need repair, use the diagnostic tool introduced in Section 5.2.
5.4.1 Power Supply Circuit
This section indicates possible causes and checkpoints for different of power supply circuit. The
checkpoints include waveforms for normal operation. By referring to the checkpoints, determine the
detective component and perform the proper repair. Table 5-6 has the following four columns:
Symptom: Check symptoms against those given in this column.
Cause: Check problems against the causes listed in this column.
Check Point: Use the instructions given in this column for troubleshooting.
Solution: Make repairs according to the instructions given in this column.
Table 5-5. Power Supply Circuit Parts List
Location
Name
Description
IC
1A
NJM2355
Pulse width modulation control
DB
1
DBF608
Diode Bridge 100V, 6A
Qlo,
Q12
2SA1 450
80V, 500mA,
600mW
Q1
1
2SC3748
60V,
10A
Q13
2SC3746
60V,
5A
F2
—
Fuse 250V, 3 15A
F3
—
Fuse 125V, 2A
F4
—
Fuse 125V, 2A
5-17