I was involved in a modification on early versions which suffered from what looked like very weak type of co-channel interference. It was picked up by one of those shall we say “Discerning” customers, you know the type. To be fair it could only be seen mainly on a blank or very dark scene, once seen you couldn’t unsee it. I found that most sets were afflicted and set about finding the cause. The issue was ripple on a supply rail caused by the 7 segment LED driver IC, this ripple was being modulated on to the outputs of the contrast and brightness D-A converters. I came up with a modification which involved upgrading the value of two supply decoupling electrolytics and adding a choke. I contacted Ferguson technical with what I found, they optimised the values and released a modification sheet. In the one circulated in D.E.R. I was thanked by Ferguson for my input, wish I still had a copy.
I was involved in a modification on early versions which suffered from what looked like very weak type of co-channel interference. It was picked up by one of those shall we say “Discerning” customers, you know the type. To be fair it could only be seen mainly on a blank or very dark scene, once seen you couldn’t unsee it. I found that most sets were afflicted and set about finding the cause. The issue was ripple on a supply rail caused by the 7 segment LED driver IC, this ripple was being modulated on to the outputs of the contrast and brightness D-A converters. I came up with a modification which involved upgrading the value of two supply decoupling electrolytics and adding a choke. I contacted Ferguson technical with what I found, they optimised the values and released a modification sheet. In the one circulated in D.E.R. I was thanked by Ferguson for my input, wish I still had a copy.