Service manual

C.3 GENERAL SOLUTIONS TO ERRORS
Many error codes are the result of jammed paper (physical errors), or paper
expected at specific time and location (read errors: sequence, blank page,
misprinted code, etc.).
The sensors index the number of sheets as they pass, incrementing a count
on the CPU-186. If a corresponding decrement of count does not occur from
the next sensor, a read error is generated. If error persists, consider failure
of sensor or communication problem (poor connection, etc.).
For many read errors, check that setup parameters are correct before
pursuing functional troubleshooting.
Read errors require a determination of the integrity of the pack. The operator
must look at the readings on the display and manually verify each sheet.
When read errors occur, it indicates that the integrity of the package is in
question. The 420T was not able to verify a page while stream feeding a
package. When the operator is satisfied that the package is complete, press
the DUMP key to release the package.
Once a reading error (BLANK or MISREAD) is declared, additional feeding
via the CYCLE key will continue to display BLANK or MISREAD errors, but
will not stop the machine.
Before powering up the 420T, the operator must remove any packages in
the accumulator to be sure there will be no initial error conditions.
C.3a Solutions to Less Common Errors
A rare, but more difficult-to-find problem can occur with shorts in the 24VDC
circuit. Intermittent failure of sensors (5VDC supply) can result from the
24VDC short. The short will only occur when a 24V component activates,
dropping the 5V supply across the line. The 24V solenoid may be located
some distance from the sensor which is the apparent problem: consider
what is supposed to happen before or as the sensor is supposed to read.
If either the Feeder speed or Folder speed are approximately half of the
other, an encoder channel is probably lost. (Check speeds through Test
menu on display)
Any time a new CPU-186 board is installed, the presets must be reset, or
there will be an error displayed.
If PWB errors occur (errors with PWB as probable source), pull the board
and make sure that all board components are properly seated. Re-install the
board and make sure it is properly seated.
If reader problems are recurring, re-calibrate with the calibration sheet. Feed
the sheet through several times to ensure that the reader encoder is
returning good data. If data is inconsistent, replace the reader encoder.
An “invalid calibration” error indicates that the calibration reading was more
than 15% different from the expected (stored) result. See above
420T V6LT OPERATOR & SERVICE MANUAL ISSUE 2009/06 Rev. 6/21/2011 SECTION C – PAGE 78
071-33370-400
PROBLEM ANALYSIS