Rominator I on Mac 128K issues

[rtappmeyer]

I've built the ROMinator I from Kay Koba for my Mac 128K. The build went smoothly but when I started up my Macintosh, I heard both startup chimes, the bong and the Glass, at the same time. It went to the pirate icon and after pressing R I saw a Disk X icon. It was interesting that when I double clicked the mouse, it would force eject the floppy. Then I tested again booting from Floppy, but it would just do a few seconds of reading, not reaching the Welcome to Macintosh, and just ejecting the disk. It's a known good disk.

I went ahead to do the basic troubleshooting:
1. Checked for bad solder joints.
2. Re-soldered the cables to the CPU pin's 9, 45, 46, 47
3. Verified continuity for connections on the Rominator PCB to all socket pins.
4. Verified continuity/short circuit for the 2 Jumpers (COM to 512K). (They are clear with the 512K setting)
5. Took off Rominator and re-inserted the original roms, booted up, and machine behaves as expected.

I've reached out to Kay Koba and he recommended to replace the ROM sockets on the motherboard to ensure a better fit. I have not done that yet and would appreciate any guidance. I have not desoldered anything from the motherboard. Even when I tried to recap the motherboard, I was unable to safely desolder the capacitors. It sounds to me like a daunting task to desolder all those pins from the sockets and safely remove the old sockets from the motherboard without causing any damage.

Here are some photos showing the type of sockets I have found on my motherboard.

 

[Builder68]

At first glance, I wouldn't suspect anything wrong with the ROMINATOR. What you described sounds more like an alignment problem with the floppy disk drive. Have you tested it before installing the ROMINATOR? You mentioned your machine is a Macintosh 128K—is the floppy drive the original 400K unit, or has it been upgraded to 800K? Oh, you mentioned that everything works as expected with the stock ROMs. That's odd. Those original sockets are indeed a frequent source of headaches, and replacing them is a delicate task.

 

[rtappmeyer]

Thank you for your input. It's the 400K drive. When I inserted the original roms, the floppy worked as expected, but when the rominator was inserted, the floppy did not boot and just ejected after reading a few tracks.
I've also had a set of 342-xxxx roms lying around, from a Mac Plus. I have inserted those and there is no problem. The floppy worked well with those roms as well.

 

[JustDaveIII]

I've built the ROMinator I from Kay Koba for my Mac 128K ...

I had worse trouble than you. Mine (not from Kay Koba & it was prebuilt) didn't do squat. I got a replacement "kit", assembled it myself and it worked fine. See https://68kmla.org/bb/threads/rominator-not-working.52136/ for all the testing I did.

The fact that your board does so much is good. I would verify continuity from the rom pins to the cpu pins and the ROM.E signal from (memory) BRU-1. I am thinking that one of the upper address pins is lacking. And double check that no rom pins are folded under when inserting into the socket. Check continuity on the jumpers, from the board header to the cpu pin. Not common, but could happen, that the crimp on the push-on-connector end is bad.

Since you got a "X", it didn't find/load the System 3.2 image/boot blocks that's in the upper rom area. Hence my thinking an upper address line is foobar.

However, there is still the chance the 74HCT02 chips is the culprit as it decodes some "stuff". I've got an order of 10 of 'em coming in soon from Aliexpress to try out on my original board. I'd be happy to send you a few if you're in the USA.

IIRC, holding the mouse button down during startup does eject the floppy. ICBW.