No schematics? No problem! Fixing a Leading Edge Model D

I became addicted to this channel. I have almost no interest about old hardware but this kind of investigation is better that any crime series on TV

Ahh, back in the day, we referred to these as "Trailing Edge" :) We had one dedicated to burning PROMs

Great video as always. As an asthmatic, I’d regard getting winded after three flights of steps as one of my better days, but I hope your own health improves, and you’re able to get back to normal quickly.

Another great example of thinking through troubleshooting steps to isolate issues. A rare and valuable skill.

Holy crap, that was my first PC, when i convinced my dad we needed better than the ti99/4a. Mine was a later model d, 10mhz, 3.5" 720k and 30mb "ide" drive that would make my later 386 not even boot when i plugged in. Oh, and vga. Sorry about the covid dude, i had it twice last month - big same on the short of breath, take heart, my capacity has come back.

I like the simpler videos as much as the complex ones. In fact, I learn more from the simpler ones sometimes as I'm able to understand better what's going on.

Feel better soon, Adrian.

Sweet! What a classic beige box. These things were everywhere back in the day. Great job bringing the old girl back around!

When you pointed out the data lines between the character ROM and P2S chip, I immediately thought of taking the ROM out and manually driving the lines high/low.

The blue logo is simply that no one ever peeled the protective plastic off. Peel it off, it looks much better without it.

Love how you go into detail and show your exact process. ❤

I enjoyed this diagnostic and repair process, even if you made it appear trivial, a fine illustration of deductive reasoning and of your deep understanding of the inner workings of these IBM clones. The Zoyi is proving its worth on these vintage machines where the bandwidth limitations are not so much a factor. It certainly beats a logic probe. I have been watching your videos since the Adrian Black days—long enough to know that you often consider appearance to be secondary—but I think a dose of peroxide would do wonders for the front panel, or paint for that matter. It's very satisfying to see not only a functional restoration but a cosmetic one. Maybe I just don't like yellow! I don't know if you realize it but it is clear you are an inspiration to many retro-computing enthusiasts on this platform. Thanks for yet another superb video.

Hey Adrian, I had COVID in March. I'm a trained vocalist and do shows on the local level. I normally can move around on stage, even light dancing, while singing with no issues. Now, I can barely move faster than a quick walk else in completely winded. I can't stand this.

It freakin’ works ! Surely time to invent the adlib dance party. Highways.

The Leading Edge Model D was designed by Stephen Kahng, who later founded Macintosh clone maker PowerComputing. I had a PowerComputing PowerCenter 132.

Hi Adrian, I rarely comment but I love your "think first, poke around later" approach that leaves these machines with minimal changes. Really cool! Keep up the good work and I hope you get better soon, but from all I know about Covid, that might take some time (weeks or months...) and you absolutely should not exhaust yourself or you risk damaging your heart.

I love your analisis of the problem even before starting to probe the board, you really have a very good understanding of how everything works, this is GOLD! thank you.

Nicely done! A little forensics on the board verified it was similar enough to an IBM CGA to be treated like one. The rest was poke-n-peek troubleshooting - inject a signal and see what it looks like. Marvelous.

These troubleshooting episodes are why this is my favourite channel.Great going Adrian!

The same thing happened to my Ohio Scientific C1P video forty years ago: one of the input lines of the 74166 died. I had to write something for school on it with one vertical line missing which was annoying. I had no confidence in my desoldering skills so I simply clipped pin 16 and piggybacked a new 74166 on top of the old one.