LCD Monitor Component Input Problem

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!

 

You failed to mention the make and model.

 

The monitor is a Samsung SyncMaster 403T. The Samsung model code is
CK40PSNB. The service menu is accessed by pressing "MUTE, 1, 8, 2" on
the remote control while the set is off.

Thanks!