I spent a couple of hours pouring over the Bomarc schematic for the Quadra 840AV, and determined which capacitors would see 12 volts. For those, I replaced them with 24 volt capacitors. For everything else, they received capacitors rated for 16 volts. Then, I got to work soldering.
I didn't notice that C48 was missing from this one until much, much later.
With all of the caps installed, I tested the machine aaaaand... nothing. The power supply comes on, the power LED lights, but that's it. There's no chime or any other activity.
I asked around a bit, and Mac84 Steve recommended checking out a specific area near the P.S.C., where I found several broken traces. I was having tons of trouble getting wires to stick to the vias and legs of the PSC., so I tried reflowing the PSC legs.
Then, I bridged a leg, and struggled to clear it with flux and solder wick. Eventually, I got frustrated and broke out the solder sucker. That was a STUPID, STUPID idea...
I think I'd been looking at the board through the microscope for so long that I had forgotten the scale that I was working with. The kick from the solder sucker caused it to collide with the pins, which bent them all up.
At this point, I felt really, really dumb - that I'd probably destroyed a nearly priceless machine, and one that I was very excited to deliver to a close friend. I have successfully recapped probably two dozen machines at this point (
including a Macintosh Classic for LGR), swapped surface-mount chips on SE/30s, and bodged lots of wires to repair broken traces, but this one... this one broke me.
After sleeping on it, I decided to try straightening them out. With my tweezers, microscope, and hobby knife, I was able to improve things a bit, but just a bit.
Despite using tons of flux, and working very carefully, I couldn't get all of the legs to stick to pads, nor could I clear any solder bridges. I decided that I'd done enough damage, and contacted someone with better equipment and skills. The logic board went to them, and the Quadra 840AV chassis went to my friend.
There are officially zero machines left from the pile, except the ones I am keeping:
- Macintosh LCIII
- Macintosh Performa 475
- 12" PowerBook G4
- Polycarbonate MacBook
- Power Macintosh G3
- iMac G3
If the Quadra 840AV is repaired, I'll be sure to post about it here! For now, our journey ends.