HEIDENHAIN iTNC 530 Service Manual page 73

All units connected to the control are also supplied by the control (encoders with long
Low voltages
cables are maybe provided with voltage amplifiers).
and polyfuses
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.
The current control hardware thus features "polyfuses".
Polyfuses are electronic fuses that become highly resistive if an overload occurs and thus
separate defective peripherals (e.g., handwheel) from the low voltages of the control.
Polyfuses have a self-resetting function ("self-healing effect").
When polyfuses blow, error messages related to the respective device are ideally displayed.
However, error messages may appear that give no clear indication as to which device is
defective.
Defective cables may lead to interruptions and short circuits. Undefined statuses and indirect
Cables
error messages may be generated.
Therefore, check in particular, whether the cables show signs of wear or were squeezed, and
inspect the connection points.
Observe the following instructions for connecting or disconnecting any connectors:
Connectors and
females
D-Sub connectors or females
Ribbon connectors or females
Signal socket at the motor
Ensure that the terminals are firmly tightened.
Terminals
Wires and leads must not be damaged or corroded.
Defective shieldings and groundings may also result in undefined errors or in a malfunction of
Shielding and
the machine. The reason are compensating currents that are caused by potential differences.
grounding
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.
July 2010
Note
For troubleshooting disconnect probably defective devices incl. cable from the powering
unit. --> See "Error Localization by Process of Exclusion" on page 6 – 66.
Connect and disconnect straightly! Otherwise, the spring contacts in the D-sub female
connectors could be widened. This may result in contact problems!
Connect carefully and straightly with constant pressure in order not to bend any pins.
Slide the nib of the connector into the notch of the signal socket and screw the connector
straightly. Do not use force! Otherwise the pins could be bent or even pressed into the socket.
Caution
If HEIDENHAIN expansion boards are used for the SIMODRIVE system, please check
whether the grounding is implemented as prescribed. --> See "Exchange of HEIDENHAIN
Components in the SIMODRIVE System" on page 28 – 554.
6 – 73