HEIDENHAIN TNC 306 Service Manual - Manual (Page 44)

SERVICE MANUAL TNC 306/360
Page 40
HEIDENHAIN Service
9.2 Checking the Keyboad Unit
The keyboard unit can be checked quickly and reliably by means of a measuring adaptor.
9.2.1 Checking the Key Functions
Procedure:
Disconnect the keyboard unit from the LE and connect the measuring adaptor (see
sec. 18.4) to the keyboard unit.
Now, the key contacts can be measured at the measuring adaptor with an ohmmeter.
If e.g. the key
PGM
NR
of the TNC operating panel is pressed, approx. 1
Ω
must be measured
between PIN 8 and PIN 24 (see key matrix, sec. 9.2.5) of the measuring adaptor. (When
performing this test, take into account the resistance of the measuring leads.)
9.2.2 Measurement Setup: Checking the Key Functions
measuring
multimeter
keyboard unit
adaptor
Einfügen
Analog.doc, Blatt 1
*
Attention!
Always switch off the main switch before engaging or disengaging
any connectors.