Atari 80s Arcade Clock - copy

Hey boss, it's possible that the specific inverter you have "sees" 2.22v as a high. If it's not supposed to, then replace the inverter. If you have a constant 2.2 v and nothing is clocking, then it's possible that your clock signal source is bad. Im not sure if you have access to an o scope or not, but it would definitely help. One other thing you may want to look at; there will most likely be a pull down resistor on the output of your inverter. If that is shorted, then you will have a low no matter what happens. Be sure to check for cleanliness, and always clean with 99% (technical) grade isopropyl alcohol, lint free wipes, foam applicators, and natural bristle brushes. Good luck. -Jolly

Yeah alright, there's a team player! Those are some solid pointers jolly, glad to see someone on the right side!..

I noticed somethin too- I'm not 100% certain but I don't think an AC signal should be directly applied to a logic chip's input. I doublechecked and looked at the datasheet for a 74LS04, and the specs only show DC voltages going to the inputs. Just something to consider..

Thanks guys, really appreciate the help. I'll take a look into further. This machine is driving me crazy. I do have a scope and have verified that I'm getting the proper frequencies but just not the proper voltage. I believe 2.4 or higher is considered high and below 0.8 is low. Awesome post njolico thank you!

General rule of thumb with 5V logic is 2V down is low, 3V up is high, and the whole volt in between is floating (or so said my electronics teacher years ago) but depending on the chips that are used and what not (regular 7404 or as sine_eyed said 74LS04, or god knows what depending who manufactured it lol) if you're suspecting the inverter chip is bad pull it out of the circuit completely and hook it up to it's own supply ect. and test it to see if it functions properly or not, it's a good way to test any component in question really, remove anything external that could bug it and sometimes you'll pull the whole board and the last part you check's the issue, but this is the fun world of electronics ;)

I think I'm more curious why the input to the invertor is at 2.22v when all the Sims create 1.5 ish. I have a logic comparator, just need to pick up another LS04. I think if the voltage was floating but on the low side verses the high I'd have a better chance of getting the high out of the invertor like I believe I need. That invertor line is feeding into the "up" input of a LS193 counter.