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Broken Corners I've seen enough broken cases that I lean toward being pragmatic rather than attempting a pristine repair. A common fracture is on the middle sides where the screen's hinge clips are secured. I usually can recover the broken pieces during disassembly. In this case, a broken-off...

I bought a backlit Macintosh Portable (M5126) that needed a recap and minor cleanup. Upon powering up, everything initially worked. However, within 30 seconds I could smell burning and quickly switched it off. I removed as many accessories (cards, hard drive, floppy etc) and tried again...

I recently picked up an 8600/300. I ran across a couple of interesting tidbits while playing with the computer. This is the enhanced model of the 8600 (Kansas motherboard) and stock 604ev @ 300 MHz CPU. For my tests, I'm using System 8.1 with the default extensions. RAM The computer came with...

A seller offered this IIfx parts machine on eBay for $200. The seller was completely honest in the listing -- so all problems I describe in this post were risks I assumed. In the eBay image below, you can spot rust, missing CPU/FPU/ROM, and three RAM simms that differ from their mates. Rust on...

I just bought a Dynamic Engineering Macintosh Portable RAM card with 2 MB of RAM installed. I also purchased new old-stock Toshiba TC 518512FL-80 PSRAM chips to bring the card up to 8 megabytes. My plan is to use this on a 5120 (non-backlight) Portable. The jumpers on the 2MB card are all...

@JDW posted some interesting Apple TIL articles back on thread regarding the PowerBook 100 and 170. One of those articles refers to the 'low power' mouse and EMI shielding in a long ADB connector. I located one of those mice, but the cable was disconnected, so I wasn't confident it was really an...

I just picked up a pre-release Color Classic. Notice that it is missing the word "Macintosh" beneath the Apple logo, the words "Color Classic" on the bottom plastic insert, and the QuickTime sticker on the lower right. The plastic has not yellowed. Looking closer, there are no signs that the...

A while back, I picked up a loose Macintosh II motherboard for the sole reason that it contained the rare (not valuable, but rare) recalled Macintosh II ROMs. These ROMs contain a bug that prevents NuBus cards from accessing more than 1 MB of NuBus space. However, the board itself was trash...

The other day, I posted about repairing some Macintosh II motherboards. https://tinkerdifferent.com/threads/macintosh-ii-advanced-diagnostic-techniques.5020/ Two of the 'dead' motherboards had bad 31.3344 MHz oscillators. I thought it would be interesting to open up the oscillators and try to...

The Macintosh II computer motherboard revision 820-0228-A is the most common. Unfortunately, it is the most corroded due to using many more surface-mount electrolytic capacitors. Nearly all of the repair work is located around these leaky capacitors. The techniques described in this post are...

As I have been looking at the Macintosh Portable in more depth. I've run across a couple of pieces of technical information that may be valuable to other developers. PRAM The original Macintosh computers (128, 512) had 20 bytes of PRAM (parameter RAM). This battery-preserved memory stored a...

The Macintosh Portable has a certain cachet. It possesses an exquisite keyboard, a crisp screen, and a complete set of ports and slots. Unfortunately, the size, weight, and price were derided at the time of launch. Presently, the challenges of a Portable are: 1. Most cases are cracked due to...

The Macintosh II and Macintosh IIx originally had soldered-on batteries for retaining parameter RAM memory and the clock. Later versions of the Macintosh II motherboard and all versions of the IIx motherboard had holes and spacing to accept batteries holders directly. (You can use these holes...

Digging around in the ROM and source code, Apple originally planned to include removable disk cards on the Macintosh Portable. This would have predated PCMCIA cards. In the source file, EDiskDriver.a, Gary Davidian ("GGD") appears to have begun work on EDisks around June of 1988. He first...

A couple of curiosities I picked up -- APS SCSI Power Plug II. I assume these allow you to 'hot swap' or 'hot power' SCSI devices. Insides pictured below: X1 is a 5 MHz crystal. U11 is a MAX632 step-up voltage regulator L1 is an inductor needed by the MAX632. U8, U13 are 74HC00A NAND logic...

I've been researching the Apple system routines that use LongDateTime as part of a potential solution to the 2040 problem. Because it is first documented in Inside Macintosh Vol VI, I assumed that those routines first appeared in System 7. But, on closer inspection and with some testing, those...

On @JDW ’s thread regarding the Macintosh Portable (https://tinkerdifferent.com/threads/powerbook-100-170-owners.4811/), he posted a link to a technical note...

I recently received an SE/30 that was sold as working. Without trying the machine first, I broke it down, recapped it, and ultrasonically cleaned the motherboard. Unfortunately, upon powering up for the first time, I was greeted with the Simasima display. It turned out that there were several...

I purchased a IIfx that appeared to be in great shape. No battery leaks. Light capacitor leakage (no damaged traces). I recapped it and cleaned it with an ultrasonic cleaner. With the original memory in Bank A and Bank B, I would get sad mac chimes. In Bank A only, it would chime but not...

Someone asked to have SimpleText open a smaller text window at startup. Initially, I assumed this would be a fairly easy fix by just overwriting a few constant values in SimpleText code. It turned out to be a pain -- but I learned a lot along the way. You need to have the code editor (from one...