Service manual

EPSON Stylus Photo 870/1270 Revision B

TROUBLESHOOTING Overview 72

7 Check if the head

FFCs have come off

the printhead.

Remove the head FFC holder from the CR unit,

and check that both FFCs are properly

connected. Even if they appear to be properly

connected (not slant), try disconnecting and

then connecting them.

8 Check if the head

driver is defective.

The common driver transistors Q3 and Q4 are

attached the heat sink on the main board. To

check their conditions, check the sawtooth

waveform at the emitter terminals the

transistors using an oscilloscope.

Table 3-15. Cleaning Does not Solve the Problem (continued)

Step Checkpoint Action

Head FFCs

Head Board

20V

tr32

9 Check if the pre-

driver IC (IC10,

IC11, or IC13) is

defective.

If the waveform is not output in the previous

step, check for the waveform at the base of Q3

and Q4. Check for the sawtooth waveform

output from the pre-driver IC.

• If the correct waveform is output, transistor

Q3/Q4 is defective.

• If the correct waveform is not output, the pre-

driver IC is defective.

Table 3-15. Cleaning Does not Solve the Problem (continued)

Step Checkpoint Action