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Does anyone know where I might be able to source the dfac chip for the classic II, I've checked the audio amplifier IC and using the datasheet to test it it looks fine. I can't find a datasheet for the dfac chip, and I think it's bad. I want to replace it to see if the audio works.

Another note is that 12v and -12v on logic board is different.I turned the Mac on its side to measure, and 12v is 11.47 and -12v is 11.74. the -12v is higher.

Another quick note, the system boots at 4.85v but is unstable, best I've found so far is 4.80v

I finished reflowing the entire board and Mac logic board is no longer sensitive to movement, however I still can't raise the voltage above about 4.85v (read from floppy port) and 11.61v. If I raise voltage to 5v the Mac either freezes on startup, or gives random sad mac error code. The audio...

I just finished running a heat gun across the entire back side. I'm going to reflow the solder on the chips on the front side as well. I noticed a crack near where the ram is while reflowing, I did have some issues with the ram, so I might have fixed it, but I'll reflow all the chips and whatnot...

I can't exactly pinpoint where the cracked joints are, everywhere I tapped made it worse, but I got a bus error when I turned the Mac on its side, could that point toward the right direction? I don't really want to reflow all joints, but I'll start doing that now since there's probably no way to...

Thanks, I'll try and reflow the solder on logic board. Another thing I did was check diodes dp3 and dp4, that I heard go bad. I desoldered them and checked them, and they were fine. Hopefully reflowing the joints will help.

I had another question about classic II. It seems every time I adjust the voltage to a perfect 5v it freaks out. I'm attaching an image. I also noticed that it does this if I don't have the back cover on and I jiggle the logic board. Is the Mac classic II logic board sensitive to movement?

I just realized I said 5.8v and not 4.8, I want to clarify that 5v is 4.8v not 5.8v. I have to keep both rails below their rated voltage.

I just tested a laptop charger and USB port and they read correctly, so I'm getting mixed messages. I don't know if my multimeter is accurate, so I'll try and get one to compare to.

I tested multimeter on a battery and it read 1.6v, tested 12v barrel jack and it reads 14v, yeah thanks for pointing that out. This is a brand new multi meter, so I figured it would be correct, but I guess it reads a little high on the dc side. Testing it on an outlet reads a perfect 120v, so ac...

Thanks, I tested it this morning and the speaker works, this is Mac classic II though, and not SE 30. Just wanted to mention that, but now I can cancel new speaker order since it works. I also want to mention that I have to keep the 5v and 12v rail low or else it won't boot. 5v is at 5.91 right...

I tested out shorting the pins on the audio jack today, but that also didn't work. It actually corrupted the picture shorting those pins. I was wondering if you could test your speaker to see if it is magnetic, mine isn't and I think that might be an issue. Metal doesn't attract to the back of...

I managed to submerge the jack in vinegar, and cleaned up the corrosion. The switch has perfect continuity, but still no audio out of internal and external speakers.

I checked continuity of the switch and it was fine, I'll try to jump it tomorrow, hopefully it's not the sound chip, I wouldn't know how to diagnose it either.

I tested continuity from the logic board to analog board to speaker and it was fine. I tested to see if anything shows up on line out pin when Mac is turned on but nothing shows up.I checked the switch on the 3.5mm jack and it was stuck, but moving it to the right position didn't do anything, I...

Thanks that helps a lot, I managed to recap both boards, grease up the floppy drive, even was able to repair the HDD, but the speaker was the hardest part to figure out for some reason. I looked at other forums and it says there might be a switch at the back of the line out jack that's stopping...

Hey what speaker replacement did you use? I have no audio on my classic II, and I'm looking for the right replacement speaker. I was also wondering if classic speaker is supposed to be magnetic, as mine is not.