Checkerboard Pattern on Mac 512

[macfan2350]

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!

 

[macfan2350]

I'm honestly not even sure if the motherboard is at fault :/

 

[macfan2350]

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

 

[Crutch]

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 ....

 

[Dog Cow]

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.

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?

 

[Crutch]

Pretty sure those are custom ROMs from an eBay seller I’ve bought from before. If so they’ve been legit in the past but do try reseating them.