HEIDENHAIN iTNC 530 Service Manual page 24

Low voltages All units connected to the control are also supplied by the control (encoders with long
cables are maybe provided with voltage amplifiers). It is thus possible that defective connected
units or also damaged cables have an influence on the low voltages in the control and generate
a variety of error messages.
Only the newer control hardware is equipped with the so-called polyfuses. These are electronic
fuses that separate defective peripheral units from the low voltages in the control in case of an
error. Polyfuses are equipped with a self-resetting function ("self-healing effect")
Shielding and Also defective shieldings and groundings can result in undefined errors or in a malfunction
grounding of the machine (e.g., vibration of axes, poor surface of the workpiece). The reason are
compensating currents that are caused by potential differences.
Therefore, check the terminals, shielded cables (the shielding braid must not contact the 0 V
conductor inside the cable), cover plates, grounding bars, contact plates, etc.
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Always disconnect suspicious units from the control for error diagnosis!
If necessary, deactivate these units or the axis concerned in the machine parameter list.
Note
It is not sufficient to deactivate a suspicious axis with machine parameter MP10 (without
disconnecting suspicious units).
The corresponding units (e.g., position encoder for this axis) are not monitored any more but
are still supplied with power. The defective scale can thus influence the low voltages of the
control, for example!
Note
If you are not in a position/allowed to activate the axes with MP10, MP subfiles might be
active and/or this is not permitted by the PLC program. --> Ask the machine manufacturer!
Switch on the control and check whether errors still occur.
Caution
For trouble shooting do not connect obviously defective controls (e.g., position encoder
with short circuit after entering of humidity) to other input connectors (z.B. X1-X6,
X35-X38) of the control.
Defective cables may result in interruptions but also in undefined conditions and direct
error messages. Therefore, especially check possible worn and squeezed positions of
the cables.
Caution
If HEIDENHAIN expansion boards for the SIMODRIVE system are used, please check the
mandatory grounding.
--> See "Important Notes on the Use of HEIDENHAIN Interface Boards in SIMODRIVE
System" on page 29.
HEIDENHAIN Service Manual iTNC 530