Can I substitute a 74HC75 for a 74LS75?

[Tony Miklos]

Actually I have done it and it is working, but can it be expected to
last? Or should I order some LS's and install what was originally in it?

If it matters, it's being used on a video arcade game mother board, Ms
Pac-Man to be specific.

Thanks,
Tony

 

[Tony Miklos]

CMOS chip inputs must be tied hi or low so that they don't drift into
linear mode pull excess current and get hot. Any unused input that is
NOT connected should be tied to + 5. Unconnected output pins can be
ignored. You may run into quirks if they were pushing to the edge of
the clock speeds. An HCT chip has the input thresholds more closely
matched to TTL and may work better.

G²

Thanks, I'll order some LS's, I'll need them sooner or later anyway.
Don't exactly know where or why I got the HC's, it's not something I
normally see in my work.

Tony