Epson Stylus Color 760, Service Manual

Page: 70 / 172

EPSON Stylus COLOR 760 Revision C
Troubleshooting Overview 70
6 Is any ink tube
disconnected from
the cap unit? Referring to the figure below, check the following
points:
• The ink tube is inserted to the Cap assembly
securely as following figure.
• There is no damage on the ink tube.
7 Is the FFC
disconnected from
the printhead board? Remove the Head FFC holder from the CR unit,
and heck that two FFC is properly connected. Even
though no slant connection nor disconnection is
found, disconnect the FFC once and install them
again.
Table 3-15. Cleaning does not Solve the Print Problem (continued)
Step Check Point Action
Head Board
Head FFC
8 Is the head driver
transistor defective? If you see the C298 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.
Table 3-15. Cleaning does not Solve the Print Problem (continued)
Step Check Point Action