Jump to content

Checkerboard Pattern on Mac 512


Recommended Posts

Hey guys! Have another question for you guys

 

Yet another entry in my Macintosh 512 repair saga. Previously, I fixed the analog board, discovered I had no roms and ordered them. Today, I plugged them into the board, however the issue of the checkerboard is still persisting. When I turn the power on, i get a "PRRRRR" from the speaker in place of the startup "bong" noise, a small bit of activity from the drive and that's all. What is going on here? I can also send more pictures if that is required.

 

Any help is welcome

 

Thanks!

 

 

IMG_1837.JPG

IMG_1879.JPG

Link to post
Share on other sites
3 hours ago, macfan2350 said:

If I put a disk in, it will just linger there. No activity

That's expected behavior for a machine that does not chime and shows a checkerboard pattern. The "small bit of activity from the drive" may be the track 0 calibration. The 400K Sony drive pulls its head back to track 0 at power-on.

 

Check your ROMs. They look homemade and suspect. Maybe they need to be reseated. Maybe they need to be replaced.

 

 

 

1 hour ago, Crutch said:

Sorry, what is that upgrade board on the left?  From the other thread, were you guessing that’s a 512k upgrade to the 128k motherboard?  How is it attached?  What happens if you remove it?  Just curious ....

I counted sixteen 256-kilobit DRAMs, so that's probably a 512K upgrade board.

 

Also: is it just me, or are an awful lot of those ICs soldered on the motherboard bearing a 1986 date code?

Edited by Dog Cow
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...
×
×
  • Create New...