Service manual

June 21,2004 2-11
NP88 FLEX DECODER
Troubleshooting
No Backlighting
Ensure the following before initiating this troubleshooting procedure:
a. Verify the low cell indicator is not activated. If it is, change the primary
battery.
b. Verify the backlighting is activated correctly by pressing any of the
buttons.
Figure 2-11. No Backlighting Troubleshooting Flow-
chart, FLEX Decoder
FAIL
NO BACKLIGHTING
CHECK SIGNAL AT
µC
PIN 57
FAIL
REPLACE DECODER
BOARD
CHECK SIGNAL
REPLACE LED
DRIVE CIRCUIT
OK
OK
AT D5
FAIL