Is 74HC164D the same as mc74hc164adg?

[liquidzorch]

Hello. I got a heat press machine in today. One of the chinese cheap ones. And the controller would not turn on. It just beeps contantly. Anyway, I found that the 5v rail was at 3v. After looking around it seems the 74HC164D that controls the LED numbers, has pins 7 and 8 shorted (~1ohm). Pin 8 is clock, and pin 7 is GND.

The clock pin is getting 5v from another controller HT46R47. Which gets warm (since it is leaking the 5v to gnd).

When I remove 74HC164D from the board the 5v rail goes back to normal voltage and the other chip does not get warm.


Two questions:


First:
The clock pin gives me 5v with a normal multimeter (I dont have an osciloscope). Would that be correct? Or is the clock line wrong? The board has a 4.0000 crystal connected to the HT46R47.


Second:
Can I replace the 74HC764D with a MC74hc164adg? It is the only one I can find in Mexico. In the data sheet the pins are the same, but the max mhz rating is different.

Any help would be great. Thank you.

[stj]

Re: Is 74HC164D the same as mc74hc164adg?

the letters at the end normally indicate the package type and how they are packed.
so make sure your getting the right package.

you can also use 74AHC series to replace 74HC series.
speed is unlikely to be a problem.

the clock pin should be switching between 5v and ground.

[liquidzorch]

Re: Is 74HC164D the same as mc74hc164adg?

Thanks. Ill order one and hopefully that will solve the issue.