Section 2: 3-6 Control Head CDM1250 / PRO5100 / CDM1550 Series / PRO7100 Troubleshooting Flow Charts
6881091C63-F
2.4 Troubleshooting Flow Chart for Back Light
Power up alert tone sounds, Volume knob works,
indicator lights up, display works, but back light does not
turn on
NO
YES
YES
NO
U0831 Pin 58
is toggling?
Base of
Q0934
> 0.7V?
Check / Replace
R0847 / C0843 / R0943
Check for short
U0831
YES
NO
Collector of
Q0934
>5V and < 11V?
Check / Replace
Q0934 U0931 /R0941 /
R0942 / R0944 / R0945
Check / Replace
Q0933 / R0947 / R0948