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Before placing an order for a replacement hybrid and display cable, I've taken some additional measurements of the LCD signals. Here's what I found. The display contrast voltage is +3.75V. On a happy chime, FLM is +262mV, CL1I is +308mV, and CL2I is +2.56V. On a death chime, the voltages are a...

That makes sense. I was under the impression that Q14, Q15 and Q20 were expected to have +5V at the drain based on what I had read here, but that's not necessarily the case. Indeed, it would explain why Q14 and Q15 are driven by pin 41 rather than pin 8. If that's the case, I wonder if there's...

Thanks Rudolf! I've conducted the majority of the tests by supplying +5.2V directly to Q14, Q16 and Q20, and only run a limited number of tests with +6.6V on the battery connector. Yet, the original state of the machine (with the broken traces I've mentioned) had originally caused battery...

I've made some additional (good) progress. Since last time, I have: 1. Replaced R22 and R23 2. Repaired the broken trace between R22 and C27+ 3. Repaired a broken trace between C25+ and pin 52 of the hybrid I've also thoroughly washed the logic board with distilled water and soap, as well as...

Quick update: 1. I've added a patch wire from C26+ to Pin 51 of the Hybrid, and from R159 to C17+. They bypass two traces that went under the hybrid and that were most likely broken due to corrosion. 2. I've desoldered R22 and R23. They were both quite corroded, and after pulling them they...

A few years older and possibly somewhat wiser, I've decided to revisit this project – especially in light of the recent progress with new hybrids and display cables being made. As a quick rundown, the machine had been recapped already, so I left the caps alone. I've recently tried firing it up...

It could also be a bad floppy drive, usually a dead chip in the drive itself doesn't prevent it from showing some sort of correct behavior; for instance, if one of the socketed chips inside the drive itself is bad, you may end up with a drive that is normally able to read but not to write any...

Yes, mine did exactly the same thing. A couple of things you can easily troubleshoot when you get it: 1) Check that the motor spins freely if you move it with your finger. When I got mine, it had become stuck just a little bit, so I was able to turn it manually but it wouldn't spin up on its...

Hi all, long time no see! :) I always felt I should share my personal collection with you, but I could never find the time to take proper pictures of it. Well, as a matter of fact I still haven't, but I figured I could just start the topic and progressively add more items! So I'd like to...

Hi all! I kinda forgot about this topic, but recently Ferrix was able to figure out the issue. It turns out it really was a matter of SCR, for some reason the modern replacement just didn't work in my particular board although it worked perfectly in a similar board. We actually were able to...

SCR has now been replaced!  We've got some progress, but we're still in need of some help.  At the moment, we are able to get a "stable" raster (albeit it's somewhat shaking in the corners) by supplying exactly 63V to the board through a variac. Any more or less and the system enters an endless...

Hi all, Ferrix and I finally started the long troubleshooting process to bring this poor guy back in shape again. So far we are focusing on the logic board, which is probably the most problematic. As a first step, we have confirmed that the installed ram is effectively summing up to 128kb...

Just bought myself one of these - late 2007 santa rosa model, for 30 bucks! Cosmetically in great condition - it was used very very little, the battery has less than 200 cycles and the keys are practically mint. It doesn't even have the classical cracks on the top case that almost all machines...

Wow, you never stop learning... I didn't know such a thing even existed! I guess I always thought monitors worked like magic (: So as far as the video goes, nothing to worry about. I'll have a full recap of the board and keep you updated!

Hi everybody! While I still haven't had time to fix my 128k, I managed to grab a Color Classic the other day. The opportunity was too good to pass up, because these things don't show up that often in Italy.  To the point: the machine was sold as non-working because the owner didn't actually...

They still teach us the 68k assembly and microcode at my university - from an architectural point of view, it's an incredibly elegant design. Much more convenient to use than the cumbersome syntax of the x86 family, and it provides a great deal of extra flexibility too.  My favorite feature is...

Gorgonops, I'm equally disappointed as well. If at least the memory upgrade had been still in place, it would have been an interesting modification to have. Sadly, it could be hard to restore it; it seems most of it is still in place, but a couple of wires have already been cut here and there...

Yep, the original seller (the american one) said that a certain point this board was upgraded to support 1MB of RAM, which basically converted this thing into a Macintosh Plus minus the missing SCSI port. Since then, the chips have been reverted to the stock ones, with the exception of not being...

Hello everybody, I'm back again with another conquest of mine! This time luck has brought me nothing less than a Macintosh 128k, which I obtained from a guy in Italy. Now, the story of this poor guy is an unhappy one, unfortunately. The guy who sold me this one said it was in working order and...

They *should* be fine. Q3 seems to be actually the same component (BU406), while the replacement you found for CR1 is an upgrade of the original component, with response time of 150 ns instead of the original 200 ns and similar current/voltage specs.  If you want to go with a component which is...