I am making a score board using 3 4026b's counting up to 999. All is working but the first 7 segment displays 1, 2, 4, 6, 8, correctly but 3, 5 and 9 the top les of the 7 segment does not light up. It lights up for a 2, 6 and 8 but why not the other numbers?
Please help!

Thanks
Mark

 

Can you post your schematics? It's kinda hard to determine how you have it wired..

 

For future reference, the MC14553B is a 3-digit decimal up-counter with all of the display multiplexing and the segment drivers built in. Saves a bunch of wiring and testing.

http://pdf.datasheetcatalog.com/datasheets/105/501162_DS.pdf

ak

 

Welcome to AAC!

All is working but the first 7 segment displays 1, 2, 4, 6, 8, correctly but 3, 5 and 9 the top les of the 7 segment does not light up. It lights up for a 2, 6 and 8 but why not the other numbers?

Sounds like a bad IC to me. Have you tried swapping the IC driving the first digit with one of the others?

 

Welcome to AAC!
Sounds like a bad IC to me. Have you tried swapping the IC driving the first digit with one of the others?

Yes several times, it does not make sence as it shows 1, 2, 6, 8 fine but others misses out?

 

Circuit, schematic?

 

Have you examined the relationship between 1, 2, 4, 6, 8 and 3, 5, 7, 9 and segment a?
Look for a short between segments a and e, i.e. pins 10 and 11 of the CD4026.

 

Have you examined the relationship between 1, 2, 4, 6, 8 and 3, 5, 7, 9 and segment a?
Look for a short between segments a and e, i.e. pins 10 and 11 of the CD4026.

Thanks I thought I had cleared any solder away but after clearing again the 4026 works brilliantly.

Thank you for your help
Mark