Top left side screen shows video 5

Just reset the TV to its factory settings and check. To do this you have to enter its service mode option. How to enter the service mode option is described in one among the posts at the site linked here.
But, before doing this reset, just connect the HDMI cable to the TV, and input an HDMI signal to it. If there is no input signal, the set will display as 'no input'. Check this first. If you wish to get further assistance from me, come over by FiXya comment.
If you wish to get some details; check the site linked here. Viewing it in "Mosaic" will make surf easy.
http://electronicshelponline.blogspot.com/

Four blinks - No vertical Deflection (V STOP), Screen goes to a single horizontal line then the video signal muted. Check IC1509, Q1505

the KV-30HS420 model is a CRT based set and thus has no "lamp". What is hte proble with the set?

Dan

hello, you should press the display button
at the remote control that marked with the i letter or with the ? sign . good luck!

U HAVE TO CONSULT TECH PERSON...THE PROBLEM SHOULD BE WITH DISPLAY BUTTON OR THE MEMORY IC OF YOUR SET MUST BE REPLACED

check your manuel, they should be a display button to press to get rid of it, a rectangle with a + in it on the button

go in touch with SONY i assume ur set is still under warrenty.....call customer help and support

dont use high volt arcing can do lots of damage. unless you can be sure comtng from speaker.

Yes. As long as your PC has an HDMI port as well (or at least a DVI port and a DVI-to-HMDI converter dongle).

Activate / de-activate by pushing display button on any Sony
remote control........................T.