Chapter 4 Fault diagnosis
SMSO-2-02.04- 15.07.03 91
4.1.6 Tips for fault diagnosis
Carry out a structured fault diagnosis. This will help you to
locate and repair the fault quickly and clearly.
Obtain an accurate description of the fault from the
operators of the coffee machine (do not accept
statements that mean nothing, such as “the machine’s not
working any more.”)
Is it an operating error or a machine fault?
What is in fact still functioning on the machine? The
answers to these questions will provide crucial knowledge
for pinpointing faults, especially at the start of the fault-
finding process. It then becomes often quite clear where
you do not need to look for the fault.
In what circumstances does the fault occur?
Is it a systematic or occasional fault (i.e. does it always
appear at the same place, time, etc, or is the fault
sporadic?
Are the symptoms always the same, or do they differ?
Are several faults superimposed or chain-linked?
Once you have analysed the answers to these questions and
made an analysis of the machine check you have an excellent
basis for locating the fault.
4.1.7 Frequent causes of faults
Some causes of faults can affect almost all parts:
Calcium deposit
Loss of water tightness or seal/ leaks
Squashed or kinked pipes
To keep the fault lists to a minimum and maintain clarity, we
have not indicated these frequent faults that may occur on
almost every hydraulic component. It is therefore particularly
important that, when you start your search for faults, or before
you start any maintenance work, you make a visual inspec-
tion of those components that make up the faulty sub-
system. It is fairly easy to detect sections of the machine that
are no longer water-tight by noticing “wet areas”, dripping
screw fittings, or even from the traces of calcium at these
points.
Calcium deposits cause pipes and components to clog up.
The narrower these points become, the greater the effect of
the calcium deposits. When locating faults, you need to pay
attention first of all to the points where narrowing occurs:
filter inserts
nozzles
baffles
valve seats
flow holes in supply pipes
If you are not sure if or which important or
delicate components (baffles etc.) are hidden,
check it in the spare parts catalogue. Here you
will find every part of a system and also the
system options.
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