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No assumptions made! The tiny trace suggests (based on the trace widths I can see and measure elsewhere on the board) that it's not 12 V, but it does not confirm anything. Unfortunately, I can't find that circuit on the schematic, and since it is underneath the power supply, I can't take...

This is a bit of a side note, but using the Bomarc schematic, I was able make some guesses at which caps only see 5 V, and thus don't need a 24 V solid tantalum cap. If someone wants to double-check my work, I would appreciate it. Capacitor Solid Tantalum Voltage Voltage Purpose C5 16 V...

I've got a IIsi that soft powers on, speaker crackles a bit, and it shows a light grey screen for a moment before the screen turns black. Is that the same symptom that you experienced, @shadedream?

I was able to verify that -12.35 V is coming from the PSU on the -12 V rail. This suggests that there's something happening on the logic board. I tried an SE/30 ROM SIMM, which caused it to hang on a white screen, instead of briefly flashing white and going black.

I was able to ask the previous owner about this, and I got a very satisfying answer: I believe they were kids at the time (I certainly was), and they probably just didn't know about or have access to the "right" way to do this. My guess is that this happened in the mid 90's to early 2000's, at...

Checking voltages would not be a bad idea! One thing to know: The Mac SE is NOT known to have bad capacitors on the logic board yet. I would not investigate that first, unless you've exhausted other options.

I have the power supply out of the machine, and would like to test it's output directly. Is it possible and safe to bench test a power supply like this? I've shorted a couple of pins on an ATX power supply before to get it to power on - I'm not sure if these Macintosh power supplies work the...

At this point, it was time to test the machine! I reached around to the back and powered on the machine, and immediately heard the horrible grinding sound of a dying SCSI hard drive. I hardly had time to think about that though, there was a super loud POP! I totally panicked, and started...

Floppy drive time! I'm not going to go through all of the details here, as I've covered them in one of my previous threads. I'll hit some high points though! Basically, I like to partially disassemble these drives, clean them up, and make sure everything is lubricated. I find that the dust +...

At this point, the capacitor order from Digikey had arrived, so I got to work! I always bend the legs like this to capture the cap. Then solder, and clip the legs... And done! My wife even jumped in to solder one of them! Her normal thing is upholstery and sewing, but she was curious...

Thanks @3lectr1cPPC! I'm super glad to hear that you enjoy them. As of this writing, it's not done, but I am getting caught up on documenting the process. Hopefully, these threads help other people with their own restorations. --- And now, my least favorite part of any vintage computer...

Time for caps! When I first started recapping SMD boards, I thought they were super intimidating, but these days, I find SMD work like this to be far easier than through-hole stuff. I struggled through recapping my Fall 2007 Xbox 360 a few weeks ago - the most difficult recap job I've ever done...

Fast forward a few months, and I've finally got some time and energy to move this project forward. The first thing on the agenda is to recap the logic board, and to do that, we need to get all of the pads cleaned up. Remember that I used the "twist and push" method some months earlier. I used...

Thanks @RFO, I'll try to find another place to take this measurement.

With everything out of the case, it was time for cleaning and retrobrite! I always like to do this out in the grass on a sunny day (I need sun for retrobrite anyway), and I mostly just use a toothbrush and some Dawn. Getting the parts super clean is not only good for their look - I think it's...

In May of 2020, a friend messaged me saying that he had some Mac stuff for me that he had picked up at his parents house. Needless to say, I was thrilled! Here's what everything looked like when I brought it home (but there are more details in this thread). Among the collection of stuff was a...

Quick update: I checked the external floppy connector, and I am missing -12v. I took the PSU back apart, and the cap that I reversed on accident is one of the last components on the -12v rail before it exits the power supply. That trace connects to two separate big coil thingies and a diode...

I just finished cleaning and recapping both the logic board and power supply on my IIsi. The fans turn on, and the hard drive spins up. The speaker on the machine clicks as it powers on, there is a white screen for just a second, and then it turns black. Nothing happens after that. It does shut...

I am restoring a couple of IIsi machines. I have gobs of 16v tantalum caps that I'd like to use up, and I have a handful of 24v tantalum caps. To avoid capacitor derating issues, I'd like to use my 24v caps in places where they will see 12v. For caps that only see 5v, I'd like to use my large...

Epilogue! It's time to finish the keyboard. And not just any keyboard... this is a beautiful Apple Extended Keyboard with ALPS mechanical switches. Not quite my personal favorite (that would be the M0116 with orange ALPS), but close. Everything is in good shape... But it does need a good...