There's plenty of help available online if you've lost the codes to your Philips Sru3003/17 remote. The first place to go would be to Philips themselves, at p4c.philips.com.
Here, you can enter the details of your remote and RCA TV and you will be able to find the correct codes for your device.
If you can't find what you're looking for there, give Philips a call on their general helpline number, 0207 9490240, or send them an email via their website.
Away from Philips, other sites provide Philips codes, downloadable manuals or general advice.
Revoxremotes.com offer a complete list of component codes, and access to a copy of the original user's manual.
similar site, manualslib.com has codes for the Philips Sru3003/27, but a forum user may be able to help you with the codes for your own model.
Two less specialized electronics forums, fixya.com and scribd.com, have threads dealing with Philips Sru3003/17 remotes, so you might have some joy at either site too.
Finally, you can always give YouTube a try. This film shows you how to set up a universal remote; if all else fails, watch and perhaps post a comment requesting help: