FujiFilm CR-IR341 Service Manual page 115

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ONTENTS
Quasi-read control
A troubleshooting signal is generated when an image anomaly occurs.
It is used to distinguish probable causes of the failure into either of scanning optics section,
light-collecting section (PMT/log amp), or scanner control board.
By selecting this mode and scanning an unexposed IP, a quasi-image signal can is
generated from each selected point to check if a normal image is obtained and to isolate the
probable cause of the failure.
1. With LIGHT, a fixed amount of light can be inputted to the photomultiplier from the LED
on the light-collecting section's PMT board to check if a normal solid image is
obtained. If the resulting image is normal, the probable cause of the image anomaly is
the scanning optics unit, subscanning unit, IP, or extraneous noise.
2. With LOGAMP, a fixed amount of current can be inputted to the log amp on the PMT
board to check if a normal solid image is obtained. If the resulting image is normal, the
probable cause of the image anomaly is the photomultiplier, high-voltage power
supply, leaked light during erasure or due to extraneous light, IP optical noise, or so
forth.
3. With SCN08INPUT, a fixed amount of voltage can be inputted to the scanner control
board to check if a normal solid image is obtained. If the resulting image is normal, the
probable cause of the image anomaly is the PMT board, extraneous noise to the PMT
board, or cable connection between the PMT board and SCN board.
4. If all of the results obtained at steps 1 through 3 above are abnormal, the probable
cause is the SCN board, extraneous noise of SCN, or image board(s) that are
subsequent to the SCN board.
Polygon control
After power-ON, the polygonal mirror is rotated.
Laser diode (LD) control
Beam-intensity detection is performed for two lasers, so that if it is less than half the nominal
level, it is judged as a failure.
If either of the lasers experiences a light-emitting failure, it is reported as "insufficient laser
intensity" (user notification warning); if both of the lasers experience light-emitting failures,
they are handled as "laser error" (system down).
Error detection
The SCN08A board detects errors related to the polygon, LD, image signal, etc.
Error detection item
Polygon
Laser beam intensity
Start-point detection
Leading-edge detection
(during self-diagnostics)
Leading-edge detection
(during reading timeout)
End-of-screen timeout
HV power supply
PMT analog power supply
009-051-04
05.31.99 FM2460
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A lock signal of the polygon motor (indicating that it rotates at a constant rate)
is monitored.
The beam intensity of two LDs is monitored.
It is checked to see that a signal is generated at nominal timings.
It is checked to see that a signal is detected upon incident laser beam.
During a series of reading sequences, the time from the activation of
the subscanning motor to the generation of a leading-edge detection signal
(until the IP reaches its laser scanning position) is monitored.
During a series of reading sequence, the time from the leading-edge
detection to the generation of an end signal is monitored.
The output voltage and noise of the high-voltage power supply provided to
the PMT is monitored.
It is checked if the power supply to the PMT08A board is normal.
CR-IR341 Service Manual
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Monitoring
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TR1H0003.EPS
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