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As seen on discord:

The Portable is a unique beast because all the voltage regulators take its reference point at the battery, and NOT the AC Adapter unlike the PB100 and newer. So the battery itself becomes the reference and also the battery becomes part of the regulation loop. If its out, well... the 1.5A AC...

I ended up fixing this machine, and the more I dove into it, the more I realized that I think someone shoved a 12V or even a 19V adapter onto this thing and blew it all up. Even the inverter had a blown winding in the transformer.

Its the batteries. NiCd/NiMH/Lead Acid batteries want to consume as much current as it can when deeply discharged to start building a charge. The circuitry in those early machines arent smart enough to provide current-limiting of its own. So the higher the AC adapter rating, its gonna try and...

Missing one-half of the waveform. Either the upper or lower transistor failed in the audio output stage, or you are missing the -12V.

They're sapphire point bearings, it allows the ball to roll around smoothly.

Woah this is amazing! PLEEEEASE Add the portable!

Here they are:

Pretty sure I have the schematics and PAL code (on hardcopy) for this card. I cannot recall if i ever made that public or not. I think i may have on the Discord.

I kinda wonder if it should just be "Power Macintosh" consolidated at this point, with the split being only old world/new world?

Not only that but audible ringing. if the core is loose, it'll vibrate at the line frequency as well as all of the harmonic/fundamentals so youll hear it sometimes. Glue stops that.

It absolutely was a flaw, and what I find even more interesting is some portables do this, while others do not. I think its crap getting in the middle layers or whatnot. But thats just a wild hairbrained guess.

I have occasionally had to bypass the high-side load switch MOSFET for the sound circuitry because it gets noisy if not, 12V hovers around 4V and causes a lot of noise. They did away with this circuit in the backlit portable, so it is safe to do.

I dont remember, been suffering cognitive decline since covid. I do know it broke free once, it cant get a good bond on polycarb. I had to grind on the original plastic quite a bit to get a biting surface or it just, wouldnt stay. And it may not.

I do want to update this thread, that this issue has become a common problem. Had a prototype portable brought to me for repair, same issue. Got some misc portable parts for free in a parts lot, and same problem. Busted off hinge. On top of the two or three I have had to epoxy back into...

I mean, they are supposed to be stiff to hold up the weight and torsional forces of the entire upper display assembly, but they arent supposed to be too stiff. The springs rotate inside the jacket and that is your friction surface. You can aide in this by removing one of the springs to...

I don't remember. Been too long ago. Pretty sure it backfeeds the supercaps. Not really supported, but i suppose it works all the same.

Problem with comparing against photos are the 40 years of technology gap in between, including photography and lighting. Apples to oranges, not even worth arguing about. That energy can be spent elsewhere. As far as swapping CCFL bulbs? Never have. Why? Because I never had to. I only swap...

Very. I have run into it multiple times, and its because the hinges get stiff. 2 reasons. the hinge plastics shrink a bit, causing the springs to shrink and get hard to move, as well as the lubrication turns to putty. But also those old polycarb plastics are starting to get brittle in general...

That backlight level is normal from what I have seen. Mine is like that, all of the ones I have worked on are like that. Flickering is also normal on some of them I noticed, it depends on the severity. the inverter design is an odd duck but its early for the time period.