Service manual

SERVICE MANUAL TNC 415B/425
Page 64
Issue: 20.08.95
11.2 Checking the Keyboard Unit
The keyboard unit can be checked fast and reliably with the measuring adapter.
11.2.1 Checking the Key Functions
Proceeding:
*
Observe the safety instructions!
• Switch off the main switch.
• Disconnect the keyboard unit from the LE and connect the measuring adapter (see section 20) to
the keyboard unit.
Now the contacts of the keys can be measured at the measuring adapter with an Ohmmeter.
If e.g.
PGM
NR
is pressed at the TNC operating panel, approx. 1 Ω can be measured at the adapter between
PIN 8 and PIN 24 (see key matrix, section 11.2.3 and 11.2.4); consider the resistance of the testing wires.
11.2.2 Measuring Setup for Checking the Functions of the NC-Keys
multimeter
X1 (9-pin)
X2 (37-pin)
TE
BC 110/B
test adapter
Ω