Need help with digital clock mod

[PartlyDave]

I want to modify a clock that uses a a Sanyou LM8560 to display 24 hour time instaed of 12 hour with AM/PM.

The 8560 datasheet says connect pin 28 to vcc for 24 hour mode. No problem there, the board has solder pads for a mode select jumper, which I have installed. The problem is that instead of driving the tens hours segments abge&d to display the number 2 it only drives segment c when the time is 20:00, 21:00, etc.


What am I overlooking?


Thanks.

[SETEC_Astronomy]

I've seen displays with four full digits on the face but only enough LEDs to display a one. Some clock use segments F&E to display AM/PM and alarm set. Have you tried to light all segments of the tens hours digit manually?