Jump to content
Sign in to follow this  
oracle_jedi

PAL 1200XL mod - goes B&W after a few mins

Recommended Posts

I installed Dropcheck's 1200XL PAL GTIA board in a 1200XL with an Ultimate 1MB.

 

The machine had a Clearpic 2002 upgrade, and the ANTIC and timing crystal (Y1) was replaced as part of the mod.

 

With the U1MB in place, the machine already had a 600XL/800XL ROM set as default.

 

After the mod the system was generating a PAL colour display, but the image switched to monochrome after a few hours.

 

I checked the install and could not determine any problems, but did also notice that the 1200XL would emit keyboard clicks, with no characters displayed, after a few mins of sitting at the READY prompt.

 

So I pulled the mod, and set the 1200XL back to NTSC. The key click went away and that machine is ok again.

 

I then installed the mod into a second 1200XL, again with an 800XL ROM, PAL ANTIC and the replacement timing crystal.

 

Again I have a color display for a few mins, then it goes to monochrome. No keyboard click this time.

 

What could be the cause of the color signal going away after a few minutes? The GTIA was pulled from a PAL 800XL that worked fine. The symptoms occur on both a Sony PVM 1344Q monitor and a Sony KV-AR25 multi-standard TV.

 

Thanks

 

Graham

 

 

 

 

 

Share this post


Link to post
Share on other sites

Has all the hallmarks of a thermal problem, perhaps resulting in a dry solder joint opening up somewhere on the PAL adapter board.

Share this post


Link to post
Share on other sites

Could be a thermal problem. At least for the colour change. Something else was going on for the keyboard clicking. Otherwise I would think it would happen on the second 1200XL too.

 

Were you using Candle's U1meg upgrade on the second machine or the more involved 800XL ROM upgrade? Also were there any mods to the second 1200XL's video circuit?

 

Just trying to eliminate possibilities. :(

Share this post


Link to post
Share on other sites

The keyboard click is generated by GTIA as well, so this also points the finger. ;) Could be a bridge to blame for that, with open circuit causing the colourburst to spontaneously drop out.

Share this post


Link to post
Share on other sites

I switched to a second PAL GTIA adapter on the second 1200XL (512K RAM/800XL OS/stock video) and it appears to generate a stable PAL colour image.

 

Any suggestions on video mods that are compatible with a PAL 1200XL? The colours are over saturated with a good deal of noise in the display.

 

Thanks for the help on this!

Edited by oracle_jedi

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...