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Checkerboard Pattern on Mac 512
Posted by: macfan2350 on 2020-02-06 12:57:05 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!
Posted by: macfan2350 on 2020-02-06 13:06:17 I'm honestly not even sure if the motherboard is at fault :/
Posted by: macfan2350 on 2020-02-06 13:15:16 If I put a disk in, it will just linger there. No activity
Posted by: Crutch on 2020-02-06 15:00:00 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 ....
Posted by: Dog Cow on 2020-02-06 16:21:08 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?
Posted by: Crutch on 2020-02-06 19:14:40 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.
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