Intermec EasyCoder 501 – Service Manual Ed. 7
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Chapter 26
26. Troubleshooting
A typical symptom is that neither the Power LED lamp on the key-
board nor the display is lit, and no beep is heard when a key on the
keyboard is pressed. To establish the cause of malfunction, proceed
as follows:
AC power failure
• Check the LED lamp at the upper front corner of the CPU-
board. If this LED is lit, the failure is probably in the display/
keyboard unit.
• Switch off power by pressing the On/Off switch at the back of
the printer.
• Check the AC power cord and the AC voltage.
• Check the voltage selector switch at the back of the printer. If it
is set at 115V, and the printer was connected to 230V, a major
damage may have occurred.
Power Supply failure
• Check fuse FU-300 on the CPU board.
• Remove strap P-302.
• As a safety measure, disconnect the cable between the trans-
former and the CPU board (P-300).
• Switch on the power again.
• Check the output voltage from the transformer to the CPU
board (pin 3 & 4; red cables) which should be 33V AC. If so,
the problem is probably caused by a malfunction on the CPU
board.
• Check the output voltage from the 5.3 V switch (left side of
R-323). If this voltage is too high, immediately switch off
power again. The cause of power failure is probably to be found
on the power supply.
• If the output voltage was correct, insert strap P-302.
• Measure the logic voltage (5.0V ± 0.1V). The red LED in the
upper, right corner of the CPU board is lit by the logic voltage.
• Next voltage to be checked is V24. Insert a strap in P-10 to acti-
vate the 24V and measure at testpoint V24 (see Chapter 17.7).
The voltage should be +24V ± 1V.
• If any of the above mentioned voltages is too high, for exam-
ple 40-50V, the associated power transistor is probably short-
circuited.
• Continue with the stepper motor voltage +40V. If the voltage is
too low (24V), the step-up switch is broken. Remove strap on
P-10.
26.1 Printer “Dead”
CAUTION!
Never replace a blown fuse without fi rst
having found and attended
to the cause!
Otherwise there is a risk of further
damage to the machine.
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