Main Board Unit Component Repair - Epson DFX-8000 Service Manual

Main Board Unit Component Repair

Table 5-5. Main Board Unit Component Repair
Symptom
t doesn't The reset signal
is not canceled.
The CPU does
not operate.
An error is Carriage error is The home
detected.
detected.
Abnormal
voltage.
RAM check
abnormal.
Cause
Checkpoint
Turn the printer on and
The reset circuit
check that pin 21 of IC (5E)
is bad.
goes High after a certain
time.
l
symptom entitled "The
CPU does not operate."
Observe the clock
The clock signal
is dead. waveforms at pins 22 and
23 of IC (5E) (see Figure
5-l 7).
The program Check that IC (38) is
ROM is bad. inserted correctly. lf it's
correct, replace the ROM.
The CPU is bad. Check that the signal goes
High and Low at pin 40
(ASTB) and pins 41 to 48
(ADO toAD7) of IC (5E).
Turn the home position
sensor on and off, and see if replace IC (5E).
position cannot
be detected. the waveform at pin 5 of IC
(5E) goes High and Low.
Observe the CR motor drive
The CR motor
signal at pins 18 to 21 (CRA
control circuit is
bad. to CRD) of IC (6A) (see
Figure 5-18).
The CPU is bad. Check if the CL signal is
active at pin 5 of IC (5E).
l
the signal route (cables,
connectors, and circuit
board patterns) to the IC
The memory Determine in which RAM the Replace the
circuit is bad. error occurred according to
the number of buzzers (see
Table 5-l).
Solution
Replace any
abnormal
element(s)
among Q2,ZD2,
C28, and the
surrounding
elements.
Replace CR2 or
IC (5E).
Replace IC (3B).
Replace IC (5E).
If it does,
If it doesnr,
check the route
of the CR HP
signal.
If abnormal,
replace IC (6A)
or IC (5E). If
normal, check
the connectors
and cables.
Replace IC (5E)
corresponding
element(s). lf
the replacement
of ICs (6C and
4C)
the problem,
replace IC (6A)
or IC (5E).
5-25