Service manual

S0740 800 179/E071123/P64
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ct33f1
AC unit
Code Description, AC unit
1 EPROM check sum error -- program memory error
Check sum test of the program memory, which is run only when initiating the unit after
power--up. This fault does not disable any functions.
The program memory is damaged. This is a serious fault, that can have unforeseen effects.
Action: Restart the machine. If the fault persists, load new software via ESAT. If the fault still
persists, replace circuit board 18AP1, which carries the memory chip.
2 Microprocessor RAM error
The microprocessor is unable to read/write from/to a particular memory address in its
internal memory. This test is preformed only on initiation after power--up. This fault does not
disable any functions.
Action: Restart the machine. If the fault persists, replace circuit board 18AP1, which carries
the microprocessor chip.
3 Error in external RAM
Read/write test of the processor’s internal external RAM. This test is preformed only as part
of initiation after power--up. The microprocessor is unable to read/write from/to a particular
memory address in its external memory. This fault does not disable any functions.
Action: Restart the machine. If the fault persists, replace circuit board 18AP1, which carries
the microprocessor chip.
4 +5 V power supply on circuit board 18AP1
The voltage is too high or too low: it must be within the range 4.75 -- 5.25 V. This fault does
not disable any functions.
Action: Turn off the mains power supply to reset the unit. If the fault persists, check the
power supply to circuit board 18AP1.
6 High temperature NTC_IC2
The temperature monitoring circuit has operated. The power source is stopped, and cannot
be restarted until the circuit has reset. See also page 22.
Possible causes: Overloading, fan not working properly, cooling air inlets or outlets blocked
or obstructed or dirt on the heat exchanger.
7 High temperature NTC_IC1
The temperature monitoring circuit has operated. The power source is stopped, and cannot
be restarted until the circuit has reset. See also page 22.
Possible causes: Overloading, fan not working properly, cooling air inlets or outlets blocked
or obstructed or dirt on the heat exchanger.
8 +15 V power supply on circuit board 18AP1
The voltage is too high or too low: it must be within the range 14.25 -- 15.75 V. This fault
does not disable any functions.
9 --11 V power supply on circuit board 18AP1
The voltage is too high or too low: it must be within the range 10.45 -- 11.55 V. This fault
does not disable any functions.