If this other Atari was a STfm, then it has composite video on pin 2 and this scrolling might be a completely different problem; one that affects some STfms when the screen content is (mostly) white. But lets solve one problem at a time...walterg74 wrote: I just tried one of my other ataris with the same cable, and while I *do* get a good picture of the desktop initially, if for example I select "about" the desktop, when the info screen pops up it starts rolling....
Correct. To my knowledge, every 1040STF has composite sync on pin 2, only early 520ST don't. I don't know why the Retro Computer Shack claimed otherwise, because on their eBay page the 1040STF is listed as compatible: www.ebay.com/itm/250978089310- My STF should have Sync on pin 2 anyway, but I would need to add a 330 ohm resistor on the cable to pin 20 of the SCART to bring it to acceptable level (although in your case you didn't need it) and that should work when connecting to my PVM.
I have no experience with that mod. But of course if all the sync signals (including H and V) have failed on your 1040STF, this won't work either.- Another option could be to modify and make my own cable where I combine the H-Sync + V-Sync signals (with a couple of resistors I saw here: http://atariage.com/forums/topic/91644- ... try1583158 ) and feed that result to pin 20 of the scart connector.
Does that sound about right?
Do you have any original Atari monitor (be it color or mono) to test with?