Epson MX-80 Technical Manual page 54

SYMPTOM 3
The carriage assembly moves properly, but none of the 9 dot wires operates to print a dot.
No.
Cause of Trouble Check Point Repair Method
1 Faulty head driving pulse
eCheck the terminal TO on the driver cir- elf the pulse width is abnor-
width, or no head driving cuit board with an oscilloscope, fDr mally short (less than 200 ,...s),
pulse is output proper voltage and pulse width. adjust VA 1 so that the pulse
width becomes 400 ,...sec at
-tpm,!
~::
"'
J-
24 VDC. See paragraph 4.3.1.
(Refer to Fig. 5.4 for the loca-
tion of VR 1.)
elf no pulse is output, the con-
trol circuit board is defective.
See paragraph 3.4.3.
2 No drive Signal is input to eCheck the base of each of the 9 head
elf no signal is input, control cir-
the head driver. driving transistors (01-09) for proper
cuit board is defective. See
input voltage. paragraph 3.4.3.
I .
l=r
Approx. 1 V
400,...s
SYMPTOM 4
The carriage assembly moves properly, but some of the dot wires do not operate to print dots.
No.
Cause of Trouble
Check Point Repair Method
. _ -
1 Defective print head unit
eCheck the driving transistor (01-09) elf the waveform is normal, the
of each dot wire that does not operate, print head unit is defective.
for proper driving voltage waveform. Replace it with a new one. See
paragraph 3.3.3 (2) for re-
placement.
~
Approx.45V
I
A+rox. 24V
I
400,...s
·1
2 Defective driver circuit elf the waveform is abnormal in the elf the base voltage is properly
above check, check the driving transis- input, the driver circuit board
tor of each dot wire that does not oper- is defective. Replace it with a
ate, for proper base voltage.
new one. See paragraph 3.3.2
elf no collector voltage is output in the (1) for replacement.
above two checks, check the Pin No.1 3 elf +24V is not output, the
of CN6 for output of +24V (in normal driver circuit board is defec-
character print mode).
tive. Replace it with a new one.
See paragraph 3.3.2
(1)
for
replacement.
I
p
I I
Approx. 1 V
Approx. 400
,...S
3-17
REV. A