7404 Hex inverter stuck on 2.5v

[evilmorty]

Hi,

I got a problem with the hex inverter. The idea is to clearly define the pulses coming in from a few optical encoders working on phototransistors, but I'm having a problem where 7404 output suddenly settles to around 2.5v.
Would anyone have any guidance on how i can fix this issue?

Many thanks
Morty

 

[Anon_LG]

Could you provide us with a circuit diagram please?

 

[evilmorty]

It's basic I don't have any external components such as pull up/down resistors


The inverter outputs will go into the MCU or a LS7084 clock converter that will take the A and B channels and make one pulse. I've yet to get to that stage to decide what will work best

 

[Alec_t]

I'm having a problem where 7404 output suddenly settles to around 2.5v.

Have you checked that with a 'scope? If the output were oscillating and you checked with a DMM, 2.5V would be a reasonable measurement.

 

[evilmorty]

Have you checked that with a 'scope? If the output were oscillating and you checked with a DMM, 2.5V would be a reasonable measurement.

Yes I'm using a scope to measure the voltages

 

[Alec_t]

Have you left any of the unused inverter inputs floating? That might produce weird results.

 

[duke37]

Is it a 7404 or a 7414 as in your diagram?

 

[Colin Mitchell]

Take everything off the chip and put 1k between input and 5v rail. What is the output ?
Put 1k between input and 0v rail. What is the output ?