User Guide

CCS Technical Documentation
NHM-4
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No
Retest
Yes
module keys OK ?
Try change LK 4
Is it working now ?
Keypad
faults 2
Measure
ROW0 to ROW4
lines from X303
Are these
Check ROW0 –
4 Lines, X303.
If OK change
Z301. If still fail
change UPP
No
Measure
COL1–4 lines
Are these
~ 0 V ?
Yes
change UPP
No
Yes
END
Yes
Check X303
No
Are LK 4
END
~1.8V ?
Press one key.
Pulses must be in all
ROW and COL lines.
If not, change
first Z301, then UPP
Change Z301
If still fail,