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Update: Classical end-user mistake! I followed Will's instructions but didn't select the right eprom type in the programmer device selection: It worked this time without a glitch. Thanks all for steering me towards the solution of the issue.

Regarding Will's video: While I followed his approach, I noticed that writing to my eprom would take a lot longer. It was minutes vs. seconds in his video. Maybe there could be a hint on what's wrong?

I fried an original ROM on another logic board (with its own issues), hence now I'm trying to recreate one.

Yes, it works with the original Apple ROM - not a silly question at all. I compared the .bin files of both the original ROM and one from the copied one with HxD and both files are the same. And I confirm that I used the same eprom type as you did.

Anyone?

I followed the instructions found here to program a new video ROM: https://tinkerdifferent.com/threads/this-is-what-a-bad-macintosh-se-30-video-rom-looks-like.1446/ To create a new video ROM, I used a GQ-4x4 to program the AT28C64. Then I compared the original video ROM file with the one on the...

Have these issues with the BlueSCSI and the Portable ever been fixed?

Thanks for this great review and video. I'm so sorry for the broken tabs of the case! Hopefully, others won't go through the same terrible experience.

Thanks. So trying to understand the guidance earlier, I will take the result (001000000000) and convert the first four characters to binary (which would be 0010 to 0000000000010000). Is that the right interpretation of the process? It feels like I missed something...

Thanks for the insights. I will power it up next week once I receive a plug for it's 5v power. Here is also a picture of the original PSU. I'll replace it with a PicoRC and driver the 68020 from the fan plug. What could possibly go wrong...

I have this 12MHz 68020 accelerator card on a Mac Plus logic board. Does anyone know what model/brand it is and where I could find the manual for it?

Thanks. How can I test chip 1B and 1F? If I understood it right, the test command would look the same for both, wouldn't it? *S *A *4 *0 00000000 *1 0000FFFF *T 000600010000 *R Edit: And more importantly: How could I distinguish which one might be defective?

@SuperSVGA Would you have any insights on how to identify the bad RAM chips?

So my Portable was re-capped and now boots with this sad Mac error: 00000003 0000FF00 Following the instructions in this thread I followed the diagnostics checks by connecting the Portable's modem port to another Mac and ran Zterm with the following commands and results in an attempt to...

Thanks, that worked. I'm attaching a picture of the set-up for future generations :-)

Where and how did you connect Ground and PA0 (Pin 2 of the VIA)? I‘m trying to get the diagnostics mode working and am stuck at this point. Also, did you take a standard serial cable to connect the two Macs? I have one that works fine for a Mac-to-Mac LocalTalk connection and will take that one.

Congrats to finding and fixing the issue. I get a similar error, though it's 0000FF00 in the second row. Which RAM chip could that be?

Thanks both for your responses. I might have found it. It’s R6 and the via connecting to it is just above the defective cap‘s pad.

The + pad of the C6 capacitor came off. I checked the logic board schematics and noticed it would connect to a resistor. However, that resistor does not have a lable. Does anyone know where the pad would connect to?