Jump to content
Sign in to follow this  
TEBL

Atari 800 XLF Color issue

Recommended Posts

Trying to debug another 800XL that has issues with the color circuit. Yes, it's another one - ordered this one as a spare so I had something to check against while fixing the other one, but when I got it I found that this was an 800 XLF revision 3 board instead (actually says XLF on the actual board). With an entirely different problem related to colors, what rotten luck :-(

 

There's some noise in the color signal and while it looks strange, the adjustment of the color pot also has a wierd effect that I'm not sure if is normal since the other one I have is not an XLF. I get vertical banding, when adjusting it seems like I'm opening colored curtains before it goes B&W (see youtube clip below, some interference with camera) instead of shifting the color spectrum. Have been trying to match this to the schematic I found by SOBOLA, but I think there are quite a few changes leading up to my revision 3 board since his revision 1.

 

Not sure if it matters, but I've been looking at the Phi 2 signal though it might be a totally wrong place to end up. Schematic connects phi 2 for ANTIC behind 74ls08 with GTIA getting signal directly from SALLY - the board however connect POKEY, PIA, ANTIC and GTIA via 08 pin 3 only leaving FREDDIE connected directly to SALLY pin 39. Is this normal, I could understand it if they were simply bridged but seems like completely separate on PCB so thinking schematic doesn't match up.

 

post-64029-0-38117800-1521972969_thumb.jpg

post-64029-0-67262800-1521973034_thumb.jpg

Edited by TEBL

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...