Mac IIsi logic board 12V rail help

[Byte Knight]

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!

 

[Byte Knight]

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...

 

[imactheknife]

I have a sound chip if needed.

 

[imactheknife]

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