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5. TROUBLESHOOTING
Trouble
1) Does not work
• Defective power transformer
at all.
• Defective LSI
2) No display.
• No voltage at VF1, VF2
• No digit signal or no segment
signal
• Defective display tube
3) No print.
• Poor voltage VM
• Defective motor
4) Poor display.
• Defective LSI
• Short or open circuits between
digit signals and segment sig-
nals.
• Defective display tube
5) Poor printing
• Timing signal is bad.
• Motor does
not stop.
• Defective printer magnet
• Missing of
digits.
• Refer to the printer service manual published separately.
Cause
Secondary voltage
of transformer
Waveforms of each
pin
VF1, VF2
Signal D1 ~
Between LSI and
display tube
— 4 —
Checkpoint
VDD, VSS, VM, VF1, and
VF2 are OK?
Check the pulse signals
S1 ~
from LSI.
If VF1, VF2, Digit and
Segment signals are OK.
VM = 11 V±5 % (while print-
ing)
Check detector of printer
block and timing signal.
Note
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