Epson Stylus COLOR 880 Service Manual page 74

EPSON Stylus COLOR 880
Table 3-15. Cleaning does not Solve the Print Problem (continued)
Step Check Point
6 Is any ink tube Referring to the figure below, check the following
disconnected from points:
the cap unit?
• The ink tube is inserted to the Cap assembly
• There is no damage on the ink tube.
7 Is the FFC Remove the Head FFC holder from the CR unit,
disconnected from and check that two FFC are properly connected.
the printhead board? Even though no slant connection or disconnection
is found, disconnect the FFC once and install them
again.
Troubleshooting
Action
securely as following figure.
Head FFC
Head Board
Table 3-15. Cleaning does not Solve the Print Problem (continued)
Step Check Point
8 Is the head driver
transistor defective?
Overview
Revision A
Action
If you see the C378 Main from the heat sink side,
the following two power transistors can be found:
• Q3 and Q4: Outputs the common voltage
To check if each pair transistor is working properly,
check the trapezoid waveform at the emittor
terminal of the charging side. Check the waveform
while running a print.
• Check the continuity of each transistor by
referring the Step 11 for the "Isolating the Faulty
Part on the Power Supply Board"
NOTE: Frequency of waveform and voltage level
(p-p) varies if printing is performed
through the driver. Therefore, as long as
the trapezoid waveform is output, the
head driver IC is considered good, and
the printhead must be replaced in that
case.
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