Help RCA tv is blocked

I have a RCA tv model number F19421.  The v-chip is set on it and my Dad and I don't know how to get it off. I have tried all the basic numbers like 0000-9999.  I don't have the manual, and  I was wondering if there was a master password or something like that.  or some way to disable it.   that would be awesome if you guys could help. thanks Steve