HEIDENHAIN
DR JOHANNES HEIDENHAIN GmbH
D-8225 Traunreut .Tel (08669)31-O
SERVICE MANUAL TNC 151/155
Page 14
Kundendienst
Section 2.2.3
2.2.3 Testing of the VDU and associated circuitry
The first objective is to determine wether the fault is
actually with the Display Unit, in which case it must be
returned to DR JOHANNES HEIDENHAIN for repair, or whether
it lies elsewhere, with the associated circuitry, in
which case repairs may be possible without returning the
unit.
Visual Display Units BE 110 and BE 211 in conjunction with
TNC 151
The Display Units BE 111 and BE 211 are supplied by an 11V
dc supply from the Power Supply Board. This is a possible
source of the fault, in which case the test and repair pro-
cedure continues according to section 2.2.4, Testing of the
mains supply and the Power Supply Unit.
If the fault is not due to a detective power supply, it is
likely to be due to the CLP Processor Board, which contains
the control circuitry for the Display Unit. This can be
verified by exchanging
the
board for one is known to function
correctly.
If the fault still persists then must be due either to bad
connections within the TNC (eg on the Connector Board), or
to faults on both the VDU and the CLP Processor Board.
See the diagram opposite for a logical procedure for
locating the fault in the system.
: ’
Testing of the WU BE 111/211 and associated circuitry
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