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The Startup/ Shutdown Nand Gates for the IIFX are UI18 and UJ18. UI18 is the shutdown Nand Gate that most likely has a broken trace preventing it from shutting down. Usually C24 and or C27 leaked on the traces. If you check voltages at the Nand Gate UI18 with power on you should be able to...

Thanks for the encouragement. I will keep trying. This is still a great project.

Not much luck. I am having issues with programming the GAL's properly. I have tried several of the suggested settings in Xgpro including GAL16V8D @SOIC20 no encryption and voltage set to 12v. (I have tried default settings as well encrypt and 16v and selecting just GAL16V8D). I still get a...

Oh I can appreciate how difficult it can be to make a board. I was lucky enough to find working replacement iifx boards. Kind of sad I wasn't able to get them to boot properly. Which is why I hope a new board can be made like the SE/30 reboots. It is remarkable with the efforts being made. I'm...

Wow that great! I have two FX battery bombed boards that both give me a death chime. I'm guessing somewhere there are broken traces from the battery goo that seep through the vias onto the interior layers. It would be great to do a rebuild the board. It looks impressive.

Nice work. I looked at that FX board and decided to pass on it. I'm glad you were able to work on it.

Wow this is great. My 512k suffered some damage from a leaky battery. Thank you.

I'm interested in the rear case bezel with the motherboard connector cutouts. Let me know how much including shipping. PM me with info. I'm in Michigan.

After a few years of working on my two Mac IIfx boards, I have put the repairs on pause. I actually was able to purchase a clean board on eBay last year and have that working. This month I was finally able to purchase another replacement Mac IIfx board. So now I have them both running again...

This is great information. I have two PM7100 boards. One with similar inconsistent booting issues that you described. My other board used to boot fine, but after sitting for a year now refuses to boot. I will order some capacitors today. Thx.

I ended up buying a replacement motherboard. I bought a 800k motherboard and installed the ROM from the FDHD board. So at least it is reading the 1.4mb floppies. I am guessing there is a broken trace near the RAM, CPU and BBU chips. I was looking at one of these MacSE reloaded boards to play...

I had a similar situation last week with a PB170. There's really no easy way to do it other than to gently pull the screen bezel at the same time you try to undo the screw. That will place some pressure on screw and enable to turn it a bit. It will take a little time and patience. The plastic...

I am still researching, but I buy my sockets from Phoenix Enterprises for a while. They have great prices. I will be buying the CPU and FPU sockets from them and was looking for the PDS socket. I was thinking of just a 3 row snap header, but there are some options. Here's a link for their...

Very nice. I just ordered some boards today. Looking forward to building. Thanks for the inspiration and the write up.

Congrats!

I am certainly interested in your repair too. I have a similar issue with my Mac IIx motherboard with no nubus. I don't get a chime (sound chip issues), but my CPU gets warm and it seems to boot, but no video. My nubus video card is also showing activity as can be seen by my thermal camera...

Start with the Nand Gates UJ18 (startup) and UI18 (shutdown) and search for broken traces due to the leaky capacitors near by. Here's image of the Startup circuit. Also a link to Doug Brown's write up on the Mac IIx start up circuitry. Even thou there is a difference with the IIx and IIfx, he...

Thanks, I will recheck my solder joints.

I do have a question about the proper chips to use with the SIMMs. I bought the PCB's over a year ago and finally had the time to build the SIMMs. I bought the 72pin SIMMs with the KM41C16000BK recommended on another post. But noticed that the built chips I also purchased are using the...

Yup, I replaced the screw that had corroded from the cap goo. Unsure on the size, I have a stash of old Mac parts and screws. I think it's a screw that holds the PDS expansion bracket on the MacSE. I'm glad it worked and glad I found your post on this card.