HEIDENHAIN TNC 306 Service Manual - Manual (Page 52)

SERVICE MANUAL TNC 306/360
Page 45
HEIDENHAIN Service
10.2 Flat Luminescent Screen BF 110
Id.No. 267 209 --
10.2.1 Checking the BF 110
If the screen remains dark when the TNC is switched on, the external voltage supply (see
also sec.8.1) must be checked at the 2-pole terminal block. If the voltage supply is correct,
disconnect the connecting cable TNC
↔
BF from the BF. Now check with an oscilloscope
whether there are signals at the corresponding signal lines. If one or more signals are
missing entirely, disconnect the connecting cable from the TNC as well and check
whether the signal lines are interruped or short-circuited. If the connecting cable is in order,
the PLC board is probably defective.
However, if there are signals at the signal lines, it is not possible to locate the malfunction
(BF or PLC board) without special testing equipment.
X1
X2
+
-