NHM-7
Troubleshooting and Tuning Instructions
PAMS Technical Documentation
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Keypad fault 1
Keypad
faults
Is the power key working ?
Measure voltage
from S300
Is it HIGH ?
No
Check R301,
C312, S300
and line.
If OK –>
Change UEM
No
Measure voltage
from S300 when
power key is pressed.
Is it HIGH ?
Yes
Chech S300.
Is it OK ?
Yes
Change S300
No
Phone is
dead
Yes
Phone is
jammed
No
Keypad
faults 2
Yes