Jump to content

Recommended Posts

I desperately need help with my 130XE that I took out of the drawer (with the intention of upgrading).

Long story short - it doesn't work... One of the two screens attached ("empty" blue screen) is what it does on s-video. The other one is with SysCheck inserted (it sort-of starts but it's not what I'd expect to see)...

Any ideas...? I replaced OS ROM, Antic and MMU - same result every time...

 

IMG_20210605_192621.jpg

IMG_20210605_192603.jpg

Share this post


Link to post
Share on other sites

Any difference if you set the sys-check to supply the base 64K?

 

Also thinking maybe worthwhile to try swapping the 74LS08 buffer with a 74HC08 or 74F08

 

Share this post


Link to post
Share on other sites

If it has ram marked “MT” - replace. That micron technology ram has the propensity to not reset after powering down.

Share this post


Link to post
Share on other sites

@Nezgar SysCheck provides 64k of ram and disables onboard Ram by default (IE dip3 set to on on off).

@Paul Westphal no MT memory on board. 

 

Wouldn't SysCheck work if memory was bad?

I mean it sort-of works but the screen is not what it should be. 

 

Btw - when booting in composite the screen is red and not blue...

  • Like 1

Share this post


Link to post
Share on other sites

OK, instead of sys-check dip3 on-on-off, any difference with off-on-off?

 

We see a GTIA 80 hozizontal pixel mode (ie Gr.9) being engaged here - so its possible GTIA is suspect, but im not sure how that could hang the system. Maybe clock buffer (74LS08) since MMU, ANTIC, OS ROM has already been ruled out... maybe CPU.

  • Like 1

Share this post


Link to post
Share on other sites

One of the causes of a power-on blue screen hang that way is a bad POKEY.  The machine is trying to poll SIO for devices (to boot a disk, etc).   Your photo isn't too clear. Is there video corruption or is that a stock-standard blue screen cursor? If the latter, try replacing pokey.

Share this post


Link to post
Share on other sites

Yes, video is corrupted (which is clearly seen with SysCheck - it's not a bad photo, it's exactly what is on the screen)

Share this post


Link to post
Share on other sites

And there's no difference when I set SysCheck dip3 to off/on/off...

Share this post


Link to post
Share on other sites

OK, problem solved. That purple patch cable got detached from 74LS08 (red circle on the picture). I soldered it back and everything is working perfectly now.

Anyway - the board is now recapped, socketed (where I plan to put upgrades ie. U1MB, VBXE and PokeyMax) and I think I'll put sockets under all RAM chips (because what else would I be doing on Sunday morning ;) BTW - those spots of flux here and there will be cleaned (just wanted to mention before the purists start screaming at me ;))

Thanks for all help.

 

IMG_20210606_102300.jpg

  • Like 3

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.
Note: Your post will require moderator approval before it will be visible.

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...

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...