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I have one of those and it never caused a crash. Are you sure it's crashing? If I remember correctly, the Sonnet pauses for a bit (like 30+ seconds), while switching to the cache card CPU.

There’s just much more of them out there for sale than the IIx and IIfx. They are quite common on eBay, and many of them are still in working condition, especially the earlier models without surface-mount electrolytics. The OG Mac II is a great machine to own. The only downside IMHO is the...

No difference whatsoever. That’s the first thing I tried.

You might be onto something here. I checked my cards again today, and the two "good" cards are using a different RAMDAC than the "bad" card. The bad one is marked “9026”, while both the good cards are using “9047”. Maybe others can check their revisions to confirm if this could indeed be the...

Hmm I’ll try the “faulty” card again in the next few days. But I’m pretty sure I had the control panel installed (the one that launches a yellow rocket during boot?) and it persisted to desktop. The “good” cards never had this issue, even before extensions are loaded. This was on 7.1.2.

Hmm I have 3 of these and only one of them has this issue. All of them are the same exact Rev A ROM (341-0812). Also, mine has the lines repeating in a different pattern than both your and the OP pictures (see my thread linked in the second post). Lastly, the issue does persist in higher...

I posted a similar thread recently. https://68kmla.org/bb/index.php?threads/apple-8-24-gc-artifacts.50006/ I believe the culprit is probably a bad VRAM ic (one of the 16 ICs in the middle of the board). I have several of these cards, so I never felt compelled to troubleshoot the issue. I...

Some of the custom ROM SIMMs use thinner PCBs and therefore don't fit correctly into the slots. However, I've never had one come loose. Is your problem caused by the metal latches not firmly gripping the SIMM?

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This is very interesting. I actually wondered about this when turning my early Mac II on, then immediately off. My IIx and IIfx will reliably turn off after a delay, but Mac II would just power-cycle instead. I actually thought I might have some power circuit issue.

I just searched my boxes of lose parts and I found a couple of those exact transceivers. You might find some used ones on eBay cheap, but it might be more cost effective to just buy a battery bombed board to steal them off of. There are probably multiple Macs that used that part. With that...

Just another follow-up. It looks like C7 must have been introducing some parasitic components (current/inductance?) to Nuchip and/or surrounding ICs. After rescanning, many of the pins that were previously showing some (minor) fluctuations are solid now. Here's an example of the first /START...

Machine is fully functional now! The culprit was a defective bus transceiver at C7. This was not obvious at all, and I'm actually surprised that I was able to track this down. All of the input/output pins, and control pins were sending/receiving signals, but the wave shapes on pins 13 and 14...

The Diimo 030 (the tall card built specifically for the SE/30) doesn’t need Twinspark and sits vertically. It’s my favorite card for these.

Looks like the grounding foil that’s normally attached to a small groove inside the back case. They are missing in most machines because they usually fall out first time the machine is opened and most people don’t know where they go.

If you're talking about the topmost corroded trace, it runs between the audio jack and pin 17 on UB11 (VIA 2). On the audio jack, there are two rows of 3 pins. So from the back of the board, it's the middle pin of the second row.

Double post.

Thanks, you saved me from spending the weekend barking up the wrong tree. Based on your advice, I probed for the interval between /START and /ACK. Without a video card, the delay was roughly 26 microseconds. With the card, the delay was only about 450 nanoseconds. So based on your info, that...

Hey all. I'm hoping someone can help me. I acquired a Mac IIx, did the standard recap and repaired some traces, pretty standard work. However, the NUBUS is not working. The machine is otherwise healthy, boots to floppy and SCSI, responds to ADB, etc. I checked traces and everything seems...

Not familiar with the TAM circuitry, but that blown tantalum can be causing a short. I would definitely remove/replace it before doing anything else. Also, I would check the ferrite bead next to it at L4 for continuity.