Troubleshooting Flow Chart For Back Light - Motorola CDM Series Service Manual

Chapter 2: 3-6 Control Head CDM1250 / PRO5100 / CDM1550 Series / PRO7100 Troubleshooting Flow Charts
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
6881091C63-A
turn on
U0831 Pin 58
is toggling?
YES
Base of
Q0934
> 0.7V?
YES
Collector of
Q0934
>5V and < 11V?
YES
Check / Replace
Q0933 / R0947 / R0948
NO
Check for short
U0831
NO
Check / Replace
R0847 / C0843 / R0943
Check / Replace
NO
Q0934 U0931 /R0941 /
R0942 / R0944 / R0945