Beeblebrox Posted March 2, 2023 Share Posted March 2, 2023 (edited) My test 800 is exhibiting the following which I presume is a passive component failing: The above occurs on both a modern LCD TV as well as CRT - both off S-video. If I plug my other main 800 in, no issues. I want to narrow it down to a passive component in the video circuit on the main PCB. (I've swapped out the power board and makes no difference - so it's definitely on the main PCB. Edited March 2, 2023 by Beeblebrox Quote Link to comment Share on other sites More sharing options...
marauder666 Posted March 2, 2023 Share Posted March 2, 2023 Try changing the CD4050. Quote Link to comment Share on other sites More sharing options...
Beeblebrox Posted March 2, 2023 Author Share Posted March 2, 2023 @marauder666Thanks. Will have a go tmrw. Quote Link to comment Share on other sites More sharing options...
Panther Posted March 3, 2023 Share Posted March 3, 2023 Or either Q105 or Q106, I can't think of which right now. Quote Link to comment Share on other sites More sharing options...
Rybags Posted March 3, 2023 Share Posted March 3, 2023 (edited) Weird, even persists onto the next scanline (note the 1st scanline of a fresh text line doesn't cop it and even stranger the first text line seems immune from it) The 4050 is a digital component and I doubt would have that amount of persistence - Q105 is just after the luma outputs are combined so that sounds feasible to me (I couldn't find Q106 on that schematic) Edited March 3, 2023 by Rybags 1 Quote Link to comment Share on other sites More sharing options...
Beeblebrox Posted March 3, 2023 Author Share Posted March 3, 2023 Thanks all.. Will investigate. I've seen ghosting to the immediate right of characters on screen before with other A8's, but never across the full length of the screen, and on both LCD and CRT. Quote Link to comment Share on other sites More sharing options...
Beeblebrox Posted March 3, 2023 Author Share Posted March 3, 2023 3 hours ago, Panther said: Or either Q105 or Q106, I can't think of which right now. Just in case anyone has it to hand where are these transistors on the 800's pcb? I am not in front of it right now. No worries if not to hand, I am sure I'll figure it out. Just idely browsing AA on a very bad connection whilst I wait to see the dentist heh heh!!! Quote Link to comment Share on other sites More sharing options...
Rybags Posted March 3, 2023 Share Posted March 3, 2023 From looking at a picture at Wikipedia Commons - Q105 about 1.5 inches below the right cartridge slot. About an inch right and down from that is another transistor but can't see a label but I'd guess that might be Q106. 1 Quote Link to comment Share on other sites More sharing options...
Panther Posted March 4, 2023 Share Posted March 4, 2023 Replacing the CD4050 is the easiest thing to try first, but if that doesn't do the trick then Q105 is what I would focus on next. It's a 2N3904 NPN transistor, and be sure to replace it with a 2N3904, as something with different capacitance will affect the video. 1 Quote Link to comment Share on other sites More sharing options...
Beeblebrox Posted March 10, 2023 Author Share Posted March 10, 2023 It was a bad 4050. Replaced it and it's working now. Thanks everyone. Quote Link to comment Share on other sites More sharing options...
Rybags Posted March 10, 2023 Share Posted March 10, 2023 Strange - the impression I had was 4050 is purely digital and the 4051 is analog (and now wondering why we use 4051s on the keyboard, maybe it has better current output) Quote Link to comment Share on other sites More sharing options...
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