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| Mac IIsi logic board 12V rail help |
Posted by: Byte Knight on 2022-09-10 16:59:54
Hey guys,
I'm still trying to get a dead IIsi I recently bought up and running. I've recapped the PS and logic board and now get a chime upon boot but the HD (known to work) won't spin up. Initially I thought it may be a PS issue as I was only getting 10V at the HD connector but I'm actually getting 12V at the internal floppy drive connector and fan leads. I also get the lower 10V at the external floppy drive port. I'm having a hard time following the schematics - does anyone have any idea what might cause this?
I got the schematics from here.
Thanks! |
Posted by: Byte Knight on 2022-09-11 07:46:40
Ok, got the HD to load up now - I ran a bodge wire from the 12V test edge lead to the HD power connector and am getting a solid 12V there now. Unfortunately I'm now running blind and deaf with no monitor to test it with and I think I may have fried the sound chip with some previous escapades while cranking up the voltage in the 12V rail, so now it no longer chimes upon boot - not even from the headphone port. It looks like the internal floppy drive is booting up correctly when I hook up my Floppy Emu, so I think the computer may be working. I've got a lead on a monitor so I'll know for sure once I can hook that up... |
Posted by: imactheknife on 2022-09-11 11:36:06
I have a sound chip if needed. |
Posted by: imactheknife on 2022-09-11 11:39:07
I also have a weird issue with my hd power supply molex. The little diodes in front of scsi were blown when I bought the board. Have no idea what’s causing it. Hope you get your board functional |
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