Recent content by polpo

It's a bit hard to find exact data for the stock fans, but another stock fan for the SE chassis is the Elina HDF6025L-12MB and it's still listed in a recent datasheet with the specs of 0.36m3/min which is 12.7 CFM, and a static pressure of 21.6 Pa. As for the Sanyo Denki fan, I found an old...

Steve Jobs and I don't have much in common, but one thing that could be said about the both of us is our hatred of fan noise. One of the very first things I do to quiet down an SE or SE/30 is replace the stock fan with a Noctua NF-A6x25 FLX. But I and others have wondered - just how well does...

All of the dumps I've made from the chip need their byte pairs swapped. Eric's output of running hexdump on 012345678987654321.bin shows the bytes swapped because that's what hexdump does by default (!). And it's my fault about the naming of 012345678987654321.bin - you're right, there's an...

So I’m pretty sure the NCR 5380 SCSI chip on this Mac Rescue expansion is bad so I’ll be replacing it. Since I have to take the Mac Rescue off of its socket anyway, it’s interesting to verify that this is really a cleanly reversible expansion. With it removed, the Mac fired right up with 128K of...

As for why is has its own 68000 instead of using the original, my theory after looking closely at the board is that it allows this board to more cleanly intercept the address and data lines to allow for expanded RAM. Other RAM expansions that I've seen for the 128k involve varying levels of...

Wow! What luck to find the Mac Rescue manual! Thank you so much for scanning and uploading it. It’s good to know that it is configured correctly for the 4MB that it has onboard. So I went ahead and took out the SIMMs and while I didn’t see any corrosion, I cleaned the contacts with a fiberglass...

I was recently given a Macintosh 128k by an old friend and it’s definitely not a normal one. The first clue it was special was a DB25 connector on the back that looked like a SCSI connector. Opening up revealed that it has a Mac Rescue expansion board with SCSI, populated with 4MB of RAM. The...

Getting the floppy with question mark is a pretty good sign that the motherboard is not yet ruined. There is a small chance that there is a problem with the SWIM if booting from floppy or the SCSI controller if booting from HDD, but it is more likely that the HDD no longer works and they don't...

If you don't want to DIY, Keystron is another source of new SIMMs using reused & NOS memory chips similar to Memory Masters. I've had good luck with them in my Macs and they're reasonably priced. They sell on eBay but the prices in their own online store are better...

I've been unable to find an exact replacement so far. I've tried using this other Alpha pot: https://www.taydaelectronics.com/b-1m-ohm-linear-taper-potentiometer-spline-shaft-pc-mount.html It has the right lead spacing and body size, but has a few downsides: the leads have to be bent straight...

I just repaired an SE board in similar state, but the SCC was in somewhat better shape. Replaced all the passives and the 26LS32s in the flooded area, needed a bodge on C13 to ground but it is working fine now!

Looks like it – the note is also on the Mac Plus's page: https://support.apple.com/kb/sp190?locale=en_US

Apple's own spec pages for the SE and Classic (still hosted on support.apple.com!) both state that 2-chip SIMMs are not supported (and by extension, probably 3-chip SIMMs also, as the 3rd chip is used for parity which is ignored): "This system cannot use two-chip 1MB SIMMs."...

Amazing restoration so far! I'd try dunking the chassis in Evapo-rust (or a similar chelation-based product like WD-40 Rust Remover Soak or Blaster Rust Remover Bath). I've had excellent results with removing the rust on battery bombed compact Macs with it. Here's the results of soaking an SE...

I thought Corona Dope was for resealing flyback transformers. It cures hard so wouldn't be good for the anode cap.