Atari 1040 STF offset RGB video image

[juansolo]

I've got an odd problem that didn't effect either my 520 STFM or STE. I've just picked up a very early 1040 STF and the RGB video image is offset hugely to the right. Now my Commodore monitor can adjust this to nigh on centre (it's my only set that can adjust that far), but it's the fact that the whole image border on the right is pretty much gone it's jammed so far over. I also have jail bar interference and a fairly dark picture.

 

I've dealt with the dark picture by swapping the resistors on the RGB lines in the cable to 75R. But other than building an RGB shifter I'm at a loss to why the picture would be so wildly offset compared to the other STs. The jailbars I can live with, but the offset thing bothers me... That said if there's no fix for it, I'll just live with it.

 

It's the image within the border if you see what I mean. If you imagine the central image with the border around, the central image is jammed to the right of the border.

Edited September 30, 2017 by juansolo

[juansolo]

An example of what it's doing.

[juansolo]

Looks like it could be a faulty glue chip!

http://www.atarimania.com/mags/pdf/page-6-issue-23.pdf

 

Page 26 details the problem and a software work around.