Hi,
I have been using an LCD monitor/TV in a HTPC setting. It was connected to the Comcast Motorola DCT 6200 HD cable box via component cables. Previously I could get HD pictures using 720p and 1080i from the DCT.
Since the warranty period is ending, I went into the service menu and adjusted the picture a little. I got the colors more to my liking. But last week, while I was watching, the picture suddenly went dark (black screen). I found that I could no longer get a picture at 720p or 1080i through the component input. But 480i and 480p through the component input are fine. DVI input is fine at all resolutions. When the DCT is set to 720p or 1080i, the monitor does not even show any on-screen menu or controls. I could switch the monitor to other inputs, such as DVI, by pressing the buttons blind. Unfortunately I don't have another source of component video output for testing. I only got a replacement cable box (same model) to try. and it did not change anything.
Since I could not get any on-screen menu at 720p or 1080i component, I am not sure if it was because of the settings I changed in the service menu at those resolutions. But I have a feeling that the service menu settings are the same for 480p, 720p and 1080i component, and I could not see anything wrong with the 480p component picture apart from the reduced resolutions.
Could anyone help me recover the 720p and 1080i component inputs? Is it because of the service menu settings I changed? (I only changed the color offsets, gains, contrast and brightness) Is it a hardware failure? If it is really because of the service menu settings, I could not confirm or change the settings back to the original because I cannot get the on-screen controls when I am at 720p or 1080i component, even though I wrote down all the original settings before I changed anything.
I also have a small suspicion that this is related to the HDCP restrictions. But the Comcast people said they didn't change anything last week, and I could still get a picture through DVI at all resolutions and the monitor does not support HDCP.
On the other hand, could anyone confirm that this is a possible hardware failure mode? That the component input fails to tune to 720p or 1080i, but a "digitally signaled" DVI picture can be displayed at those same modes?
Thanks!