HD BOX SETTINGS

According to the owner's manual page 2.7 (and this is an OLD [by HDTV standards] set), the TV can only handle input resolutions of 480p or 1080i on the composite inputs. Most HDTV programming today is 720p with some 1080i and 1080p on certain channels (like some Discovery shows about nature). It is possible that your set will not process the 720p signals being sent.

Most cable HD-boxes output either 720p or 1080i, not 1080p.
Set your TV to 1080i or 720p.
Set the HD box to the same resolution.

You most likely have to set the Cable Box to a specific resolution. Because that model only provides 720p/1080i, the box must be set to match that. You may need to use the yellow/white/red Composite output on the box to the tv first, so you can access the boxes menu and set it to 720p or 1080i, then I recommend using Component cables (Red/Blue/Green with white/red for audio) out of the box in to the TVs "Component 2" input. Now you should get a good HD picture. If you still can't get it to work, give me a reply with details and I will get back to you.

You need to change the output format from 1080i to 720p or 480p in your cable box. this set may no support 1080i.

1080p is not avalable on much right now, you will find it as a stp up option on some of the pay movies but HD is only 720p not 1080p yet. 1080i is the best you will get for now

is your cable or sat in HD(720p, 1080i, 1080p) over the air broadcast in the usa is in digital so it should start at the highest res available in your area

next are you using HDMI or composite for your cable or sat going into your tv if not your not going to get higher than 420p because A/V and S-video do NOT support HD

check your cable/sat box is it HD(high def) or SD(standard def) if SD going through cattv/attn in your only going to get 420p

now for changing the resolution its automatic it goes to the highest setting on its own

you can control the resolution through your cable/sat box, blue ray/hddvd player and other HD devices connected to the tv through the options menus of those devices BUT only when connected through

HDMI(supports 720p, 1080i, 1080p)
composite(supports 420p, 420i, 720p)
A/v and S-video(supports 420p)
cat tv/attn in(supports 420p, 720p, 1080i, 1080p) only supports what the tuner will do

i=50hz
p=60hz

There's no way to tell the HDMI input whether it should take 720p or 1080i input on this set. The best thing to do is experiment. Set your Comcast box to 720p and watch it that way for a while, then set it to 1080i and watch it for a while. The PDP42 has to do a little picture manipulation in either mode, but I think you'll find that the 720p mode will work best for you. I have this set with Verizon FiOS and I have the FiOS output set to 720p. Looks great, no complaints.

Go the the settings on the cable box. look for output resolution, then change it to 1080i and 720p. now turn the box off and back on your tv will now display the input of wither 1080i or 720p depending on the hd channel your watching.

I don't have the XBR, but on my sony, using the cable box remote, I had to go into menu/display/etc. and mark the 1080i, 720p, and 480i settings. you usually get a "if you can see this" comment if your tv accepts the settings. for standard tv i set the screen to normal, and when the upper channels go to HD, they auto go to full screen. Sounds like you are using the component cable, and also make sure you are on the video port of remote, and the the TV input. The above worked for mine. Hope it helps.

have the cable company set the box to 720p whic is the native resolution of the set.this will help with quick signal adjustment