Recently i acquired an SE30 from a colleague:
After a brief inspection of the board for battery damage (no damage!) I hooked up the power and switched it on:
Uh-Oh...
Nice pattern for my wallpaper, but for a system a bit unpractical. Also i could very faintly hear the 'chime of death'. I replaced the caps and washed the board:
Reassembled the Mac and i got exactly the same onscreen but with a louder sound:
Youtube video[/]
Using schematics, tracing every line in the video-system:
Even with no processor, ROMsimm, RAM or video-rom the pattern was the same. I then knew my problem was probably with the video-ram adress muxes or the RAM itself. The muxes are really cheap (about 40 cents a piece), so i removed them. My theory is that without them only the first byte of video-ram would be used on screen (and repeated in horizontal and vertical direction)
After removal of the muxes i got this:
As you can see there is a different pattern now. The weird thing is that it should be solid white and black bars, no intermission because the RAM is empty!
Now i suspect the videoram, i've removed the chips and ordered a bunch on Ebay. Now i wait...
I don't expect the Mac to be fully operational after this repair, but perhaps it will give me another hint on how to repair it when the video is working properly.
To be continued!
After a brief inspection of the board for battery damage (no damage!) I hooked up the power and switched it on:
Uh-Oh...
Nice pattern for my wallpaper, but for a system a bit unpractical. Also i could very faintly hear the 'chime of death'. I replaced the caps and washed the board:
Reassembled the Mac and i got exactly the same onscreen but with a louder sound:
Youtube video[/]
Using schematics, tracing every line in the video-system:
Even with no processor, ROMsimm, RAM or video-rom the pattern was the same. I then knew my problem was probably with the video-ram adress muxes or the RAM itself. The muxes are really cheap (about 40 cents a piece), so i removed them. My theory is that without them only the first byte of video-ram would be used on screen (and repeated in horizontal and vertical direction)
After removal of the muxes i got this:
As you can see there is a different pattern now. The weird thing is that it should be solid white and black bars, no intermission because the RAM is empty!
Now i suspect the videoram, i've removed the chips and ordered a bunch on Ebay. Now i wait...
I don't expect the Mac to be fully operational after this repair, but perhaps it will give me another hint on how to repair it when the video is working properly.
To be continued!