Macintosh iisi, video for a second then no video

Duke09

New Tinkerer
Oct 30, 2021
50
7
8
I’ve got a Macintosh iisi that turns on and chimes. It will output either a grey, yellow or purple screen for a second then the monitor will turn off. With no ROM it will stay on a solid color indefinitely. It also does seem to boot off a floppy disk and the cpu does get warm. It seems like a video issue of some sort but not sure where to look for bad traces or vias. I have done a lot of work on this board already with trace repairs, but still no luck. About to call it quits on this machine. Any ideas?
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I’m comparing your board versus mine in the IIsi restoration I wrote about here. I see you have the ROM SIMM instead of the onboard ROM, and you had the same trouble areas at UA5, UA6, and UE5 that I had due to corrosion from cap goo. My suggestion is to double-check your work at UE5 and make sure you have good continuity and no shorts to UA2 and UA3. Good luck!
 
I’m comparing your board versus mine in the IIsi restoration I wrote about here. I see you have the ROM SIMM instead of the onboard ROM, and you had the same trouble areas at UA5, UA6, and UE5 that I had due to corrosion from cap goo. My suggestion is to double-check your work at UE5 and make sure you have good continuity and no shorts to UA2 and UA3. Good luck!
Thanks for the suggestions. I spent a few more hours and found two more bad traces from the ROM to the CPU, and I assume the damage is under the ram slots. I tried fixing those two but it made things worse somehow. At this point I have spent too much time on it and will just part the machine out at this point.
 
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