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There are two major factors. Ceramic capacitors have a dramatically lower "ESR" than most electrolytics or tantalums. This means that they react dramatically faster to voltage fluctuations, and not all circuits are ok with that. Maybe an electrolytic was used to provide 'bulk capacitance' but...

Ceramic capacitors can't always be used to replace electrolytics. Their big advantages are neither exploding (tantalum) or leaking (electrolytic) ever. But not all circuits like them.

The display is rather unhappy with the ceramic caps I used, very wobbly. Guess I'll switch to tantalum, as much as I dislike those. Or maybe I can find teeny tiny solid polymer electrolytics.

Here's a fun tale about the differences between older parts and more modern ones. I have found a replacement opamp that works in place of the original OP20H. But this new opamp was causing odd behavior, where the 5v rail would *sometimes* (not all the time) spike up to full battery voltage for...

Recently I picked up a PowerBook 100 for cheap because it lacked the CPU card. Fortune favored me in that the CPU card was available from a seller in Tunisia and not labeled for the 100 - they had it listed by part number. Starting up the old machine resulted in the sad mac code: 0000000E...

@techknight has tested the one I sent over, and it's basically working. Revived a Portable that had been sitting around for something like 7 years. The caveat here is that the battery meter on his portable doesn't go all the way to "full "when it should. This is interesting, because testing...

That other opamp possibility didn't turn out to work, because it was too high a slew rate. Going to try another one, because supply of the original opamp is drying up and I don't have many of them.

Circling back to this project, I just tried the Samtec SMS-117-01-G-D as a possible new source for the connector on the backlit portable's screen cable. Sadly, the connector housing is *just barely* too large. The pin spacing is correct, but the socket doesn't want to fit. With a little...

PCBs are expected to be here on Thursday. I'm looking for two testers, DM me if interested.

Pictures of what? The F4 BlueSCSI products? Those are on my website.

I've tried this specific overclock configuration. It actually results in a decrease of read/write performance, for reasons I don't quite understand. Drops to 1700k read and 1500k write on beige G3. This overclock is a little weird and doesn't seem to realize that although [(25 * (500/25)) /...

This feature has been in the BlueSCSI codebase for a rather long time, actually. I think it was called out in this release because it had never been officially 'mentioned in a release notes' before. F4 BlueSCSI uses the same configuration as upstream, as mentioned in the Usage section of the...

Order is in for a small run of both PCBs: the new dual-opamp replacement and the style using original parts only.

Another pre-release set of binaries has been generated, to fix formatting-utility-related errors: Release Link: https://github.com/androda/F4_BlueSCSI/releases/tag/1.1-SNAPSHOT-2022-06-27 Firmware Update Steps: https://github.com/androda/F4_BlueSCSI/wiki/Flashing-Firmware-Updates

Digging around a bit, I found an dual opamp which hopefully can replace the original (and hard to find) opamps with one newer and cheaper chip. Going to pursue that as a possible update to the design before officially producing these. Less reliance on vintage parts is better. Haven't found...

Do we have any information about which panels are specifically affected by tunnel vision? I'm pretty sure there were 2 manufacturers for many of the grayscale displays in laptops. Do we know if it's only one brand that has the issue? The unfortunate thing is that being certain which display...

I'll try their specific configuration to see what it does.

It appears that the time has fully arrived: The A/D line is fixed, or close enough to the original that it behaves the same way. One resistor value wasn't quite right (basically the same thing I've said over and over again thus far). I can now run my Portable on battery power without it...

I attempted some overclocking this morning. The STM32F411 chip is rated at 100MHz. Overclocking to 125MHz resulted in a lockup on boot. Tweaking the F4 series' flash read accelerator didn't help. I had to change the AHB peripheral pre-divider to get the chip to start at this speed, and...

As shown in this Wikimedia image: https://upload.wikimedia.org/wikipedia/commons/7/76/Apple_Macintosh_II_motherboard.jpg It looks like things are implemented with: HAL16R8 HAL16L8 (under the nubus slots) These are the mask programmed (not flashable) versions of the more common GAL16 style...