Electronic Problems; Adjusting The Paper Low Sensor - NCR 7156 Service Manual

7156 Service Guide

Electronic Problems

Problem Possible Causes
Power Voltage too
Improper connections in
Low/High
printer.
AC supply voltage is out
of range.
Problem Possible Causes
Printer Beeps Twice at
If printer beeps twice
Power On (RS-232C
during level 0 diagnostics,
Models)
it indicates that default
values have been loaded
into the EEROM.
If the printer beeps twice
at every power on, the
EEROM has failed.
Problem Possible Causes
LED Does Not Come On
Forms improperly
inserted.
One of two sensors failed.
Failed LED.
Problem Possible Causes
MICR Not Operating
MICR not installed.
Properly
MICR improperly
connected.
MICR does not read or
misreads checks. See the
note below.
MICR cables improperly
routed, which interferes
with "OK" adjustment.
MICR read head does not
come up.
Foam pad missing or
displaced on carriage
assembly.
What To Do
Check that connections in the printer are proper. See the
section in chapter 8 that applies to this unit's PC board.
Measure the voltage with an AC volt meter and check it
against the power supply label. The voltage range should be
24V ± 5%.
What To Do
Take no action. See "Level 0 Diagnostics" for more
information.
Replace the PC board. See "Removing the PC Board" in
chapter 9 and "Replacing the PC Board" in chapter 14.
What To Do
Remove obstructions in the paper path which may prevent
inserting forms properly.
Both sensors have to be covered for the LED to come on.
Replace the sensor.
Replace the LED/sensor assembly. See chapter 10.
What To Do
Make sure MICR is installed on the printer. Run the print
test to see if MICR is installed. See "Print Test" in chapter 3.
Run the diagnostic test to verify the MICR characters and
print the Hex values. See "Verifying Read of MICR
Characters" in chapter 3.
Readjust the MICR check reader. See the section in chapter 3
that applies to this unit.
Reroute the MICR cables correctly. See chapter 14.
Check the MICR solenoid connections to the PC board. See
chapter 14.
Replace the foam pad on the carriage assembly. See
"Disassembling the Carriage Assembly" in chapter 12.
Check that the MICR read head assembly is mechanically
free.
September 1998
Chapter 4: Troubleshooting
53