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Checked the schematic, the references for the tantalums that are bypass caps for the FPU are C100 and C121. If they were actually shorted, though, you would read a short across VCC and GND whether or not the PSU was plugged in (unless I'm very much mistaken). By what method did you find there...

Have you tried swapping the P460 power supply into the P450 to see if it makes any difference? There are some tantalum caps on the flip side of the board from the FPU, almost certainly used for decoupling. I seriously doubt they've failed, but when they do, they fail shorted.

If you're having sound troubles, all of the electrolytic capacitors need to be replaced. Replace those on the logic board and in the power supply, and clean the logic board well. If a bypass cap for the FPU was shorted, the system probably wouldn't turn on even without the FPU. Since you mention...

I bought the 700MHz 12" version of this 4-5 years ago and it smelled pretty awful; buying a new keyboard and letting the iBook air out until it arrived solved that problem. It is definitely the keyboard that produces the smell but I'm not sure how you tell the stinky ones apart from the rest...

Pictures of the top and bottom of the board might help in spotting bad traces. If you've redone the solder joints on the ADB connector, take a closer look at IC U7 (between the FPU socket and ADB port). Try following the traces back from the ADB port through until you reach U7 and make sure none...

That cap is definitely leaking. The pins on U22 are noticeably more tarnished than those of its neighboring parts. I believe those two small chips are for the serial ports. The corrosion that is causing problems is more likely in the corner of the board with the audio jacks. That's where the...

I'm not very familiar with this card, but I'm guessing that cap is supposed to be a bypass capacitor for an IC (based off the fact that there aren't any bypass caps on the top side, and this one looks like it's connecting two power traces, as a bypass cap would). In that case, it should probably...

Just noticed something -- in the pictures you posted, it looks like many of the 10uF capacitors (C7, C6, C111, C5, C1, C3, C105, C108) have been replaced with 100uF parts. This may be at least part of the problem.

Here's a chart with all the size codes: http://www.resistorguide.com/resistor-sizes-and-packages/. The three numbers on the top of the resistors tell what the resistance is: https://www.hobby-hour.com/electronics/smdcalc.php.

Opened up my MP-F75W-11G to check and there are two different sizes of resistors on the PCB. Smaller ones are 0805 case code (imperial), and larger ones are 1206 case code (also imperial).

If you really want to repair the pads for C13 or any of the other capacitors, I suppose you could find a sheet of copper foil (without adhesive, can be found on Amazon), cut new pads from it, and attach them to the board with a high-temperature-resistant epoxy (I know such a thing exists but I...

Although I had a few issues with the video as well, I'm hoping it'll spread the word about recapping some, especially seeing how big his audience is on YouTube. It seems that a lot of people into classic Macs still don't realize just how damaging caps can be. Re: the twisting caps method...

It appears you can get both the SCC and SCSI controller off eBay for roughly $10 each (not my listings). BTW, when buying obsolete parts like these, it's wise not to buy from sellers in China as they have a reputation for relabelling parts as others.

I don't mean to be rude, but you haven't created some "System 6 for Windows" thing; you've bundled Mini vMac, an open source emulator that most, if not all of the members here are well aware of, with a copyrighted ROM/OS, property of Apple. It's hardly anything new.

I'm pretty sure that you would at least get a raster on the display if the SCSI and/or SCC chips were bad. After seeing all the crud that was under the Bourns filters, though, I'm wondering if there's more under one of those chips and it's shorting some signals together.

Almost certainly a power supply issue, then, given that the hard drive starts spinning down.

I've never heard of it failing, but maybe try swapping that big socketed VLSI chip next to the CPU, just to rule it out (just be very gentle to prevent cracking the socket). Also, maybe there's a rotted trace under the SCC or SCSI chip?

What exactly happened when the computer "shorted out"? This sort of sounds like a PSU problem. Was every cap in the PSU replaced? Some guides say to only replace a few, which is false.

Thank you, my mistake.  :)

The power switch, at least on my PSU, has a few wires soldered to it and is clipped into the back of the metal case.