Quorum + 5V + TV = Chess Table

Hello, All And once again I welcome lovers of ZX-Spectrum and Quorum class computers :-). The story is this: I got a Quorum that did not work, but its inoperability manifested itself in that when you connect it, I saw the following on the monitor screen: half screen is a Chess Table, and the rest half is red lines (when on Press RESET). I thought that something happened to the firmware, I replaced it, installed I connect another firmware: the picture is the same!. Question: 1) Why could this be? 2) Does the Z80 CPU firmware affect this (I want to say that it is not there dear, in its place there is a KR1858VM1 microcircuit)

Hello jerry This is either KP11 in the video controller glitching or just a short circuit. Mark of the processor this does not affect if he is not dead of course ;) (and it looks like he is not dead) To begin with, I recommend inserting some test ROM.