Recent content by dougg3

For what it's worth, on the ADB side, bbraun discovered back in the day that the TechStep sends a special ADB command on machines with an Egret/Cuda to enter the test manager, which can't be sent with a normal keyboard...

I just measured them on my stock SE/30 board that happens to be sitting out right now, and it's the same. They're marked as 1k but they each measure 519 ohms. It's definitely because they are in circuit. I think I can explain why that is in more detail: The top end of each resistor is tied...

I'm going to go out on a limb and guess that you are using a custom ROM SIMM in your SE/30. With a custom IIsi- or IIfx-based ROM in an SE/30, System 7.5 and up will hang at Welcome to Macintosh until you patch a couple of system files with ResEdit. bigmessowires saved a copy of Gamba's page...

For what it's worth, I recapped my Macintosh TV's analog board (also "630-0355-") back in 2013 and CP14's orientation matched your picture. I put it back in the same way as the original and it worked fine. There was no revision sticker at all on the board. Here's a picture of how it looked...

I don't, but it sounds like you've got your bases covered!

Well done on the repair! I've been dreading working on my Classic II's analog board that has similar leakage and metal corrosion. This is very useful info, and timely for me! Awesome! I thought I'd add for reference for future readers that mine also had a visibly corroded and non-working reset...

One suggestion I have for troubleshooting is to start out by flashing a stock Q650 ROM to the programmable SIMM just to rule out any hardware issues and prove that the SIMM and socket are both working fine. I'm guessing you won't run into any problems with it, but it might be a quick way to rule...

Thank you! And I forgot to mention here, if anyone else has a Performa 550 (or even potentially a 57x model) I'm still very curious if we can find out if there's a special lost version of Apple Backup that created it, or if it also has the recovery partition.

I found some time to write up everything and also shared as close to a factory-fresh drive image that I could create, so anyone else can download and play with this functionality in MAME. The recovery partition even works on the IIci and the Classic II, verified on hardware...

Some earlier models had the socket populated even though there were also onboard ROMs. My guess is they were trying to future-proof just in case there was a nasty ROM bug, and they stopped populating it after they were confident the ROM was good. Just a guess though. Apple designed it so that...

The search is over, and this elusive recovery partition has been found! A kind person on Reddit let me borrow the hard drive from a Performa 550. The Conner drive did not want to cooperate, but I opened it up and figured out how to unstick the head and dumped it. More details, and of course...

I second that -- if any of the boards are a lost cause, please save any of the custom chips you can. I'm sure they would be useful for somebody. I accidentally fried the flash /WE pin on my LC 475's MEMCjr (343S0164-a) chip by putting 12V on it (oops).

For sure. It's an interesting question to ask. For example, did the Performa 560 come with it? What about the Performa 57x series? I wonder if the issue they ran into with that second technote made them decide against continuing on with this concept. Either way, I find it very interesting. If...

Hi there, I wanted to alert everyone about an unpreserved piece of Mac history that Pierre Dandumont first told me about. The gist of it is that according to Apple, the Performa 550 had a hidden recovery partition that it would boot from if the main system folder was screwed up. This hidden...

Nice! Just to clarify, it's not my PCB design, but I can confirm it works :) Also, for anyone who might be shopping around for connectors, I originally bought some DA-15 connectors that didn't fit properly. The ones I linked above have a 10.3 mm backset spacing and are correct for this PCB. In...