Hello.
I've been (with permission) working on re-issuing an old board that was manufactured in the mid 80's. I have isolated my problem down to the replacement I've chosen for the discontinued Fairchild 74LS04PC chip that the original board used. When the SN74LS02N is put in circuit, the board doesn't function properly. When I put the original 74LS02PC back in, the board works perfectly. Leads me to believe there is some difference.
I cannot find a datasheet for the Fairchild 74LS02PC so cannot compare it to your TI SN74LS02N chip. Seems that there must be some difference. Wondering if someone can help.
Thank-you
Thomas