Quick question/problem on a BCD counter.

https://www.electro-tech-online.com/custompdfs/2006/08/cd40110b.pdf

^ data sheet of the chips im using for reference.


I'm building a scoreboard with LED's. 2 Digits 4 led's per segement. Simple.

I have everything wired up and in place and actually had it working on the breadboards... but now its not working correctly.


Whats happening is the first digit is not changing; however if you press the switch 10 times it will read 10 (second digit will change on time). Press it 11 it will still read 10, press it 20 and it will read 20. Etc Etc Etc. I'm baffled as to how/why it is doing this. All the solder connections look fine, the chips work i tested them. Any suggestions?

Probably the latch enable of the first counter.

Like on1aag said, check the latch enable (pin 6) of the first counter. If it's a logic high, the output from that stage will never change.
JB

And Also ensure that all inputs go somewhere.
If they are not used, by means of a 2k2 Ω pull up resistor make them positive 5 volts, or earth them depending upon the IC, I take it that you use 7490's for the BCD and 7447's for the readout ?
A 100 nF decoupling capacitor across each IC also helps for the stability of the supply.

thanks guys, it was the latch. Theres so many wires connected to the IC board I couldnt see. A piece of solder must have fell off the iron and tied itself to the neighboring input.