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PB145B

Macintosh 512K revival

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I just got a 1984 Macintosh 512K yesterday, and will be documenting the adventures with it here.

 

Here are the first pics I took before anything was done:

 

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As you can see from the serial, this Mac started life out as a 128K. Pretty cool. It’s the best of both worlds in my opinion. The awesome history of the 128K, but with the enhanced usability of the 512K.

 

First thing was to pull the 400K disk drive and clean/lubricate it. Here’s some pics of the drive:

 

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Made in August of 1984, so it’s likely original to the Mac.

 

Got the mechanism freed up, put it back in the Mac and it wouldn’t read anything. I pulled the drive back out and found that the stepper-motor was unplugged! So I reconnected it, and got the dreaded “click of death,” where the stepper just keeps turning and never stops. A quick clean if the sensor made no difference. Damn.

 

So today, I took it back out, soaked it in alcohol, scrubbed it very well with a tooth brush, and it started working! The heads go all the way back like they should now and it reads disks fine!

 

Here’s a pic of it booted from the internal drive:

 

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Wonder how long it has been since that drive has worked properly? I’m guessing a long time.

 

Another thing I found is that the analog board has been replaced. It has a date if 1991 on it!FAC9B37B-CBF7-434B-A8BD-7E1F6E2BAD99.thumb.jpeg.9dbd6528d39f06edb37aeee74a2580b0.jpeg
 

That’s all find and dandy, but the flyback makes a really loud high-pitch whine on occasion, which is not normal, so I have ordered another analog board for it. The one I got actually is the really old revision with the smaller flyback. I don’t know how good of an idea that was, but I’m a sucker for originality! Hopefully it’ll work...

 

And for anyone curious, here’s an inside-shot if the machine:

 

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And here’s a pic of it I snapped in the dark with the LED sensors in the drive glowing:

 

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Too cool!

 


That’s all for now. More to come...

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This is an incredible find. It looks pristine inside, especially that 400k. I have two refurbished 400ks that I got last March. I an trying to backdate my 128k to its' original configuration including the 400k. This is inspiring!

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Nice. I got a boxed 128k once but it wouldn't boot. According to the error on the screen, some of the RAM chips were bad. Luckily I found some NOS chips on eBay (though not the same make, sadly) and swapped them in and it worked. I left it stock because I have a 512k to accompany it. I also found an external floppy drive for it. Those drives are way expensive in working condition but those that need maintenance can be had cheaply, so that's what I did. It's funny how those old 400k drives have everything roughly double the size of the components in the later 800k drives, which themselves didn't change much when they went to 1.44MB. They sound as different to the later mechanisms as the 800/1.44 auto inject models did to the manual types, kinda like an egg beater.

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9 hours ago, LaPorta said:

This is an incredible find. It looks pristine inside, especially that 400k. I have two refurbished 400ks that I got last March. I an trying to backdate my 128k to its' original configuration including the 400k. This is inspiring!

Thank you! Yes, it’s in very good condition indeed. :) Good luck with you 128K restoration!

 

8 hours ago, Franklinstein said:

Nice

Thanks! Yeah, the untested 400K drives seem to go cheap. All they usually ever need is a little lubrication. And yeah these drives are huge! Very easy to service too. Love the way they are built. Great Japanese engineering!

 

And yeah, they sound completely different to the newer ones. I absolutely love the varying little “buzz” that the spindle makes. It’s quite soothing to me. :) 

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Here’s a pic of the current set-up.

 

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I’m using my platinum Mac Plus keyboard and mouse for now. Next items to find are an original keyboard and mouse.

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Well, I unsoldered the flyback to inspect it, and also because I was thinking about temporarily swapping the one from my platinum Plus into here so I could stand to use it (the high-pitch ringing was very intense). I decided to solder it back in first just to see if anything changed, and it has not made the ringing sound since! Maybe it really was bad solder joints. I didn’t initially reflow the flyback because it looked fine, but maybe it wasn't. I did find it odd that I could occasionally make it stop by pushing-in on the analog board side of the Mac.


Time will tell If this is a lasting fix. I’ve also still got that early analog board on the way with the smaller flyback, which I’m still quite curious about. Either way, having an extra analog board never hurts!

Edited by PB145B

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DAMN, the internal drive has given me absolute hell in this Mac today. It started giving me the sad Mac and spitting the disk out. 
 

So I completely tore the drive down, took the heads out and stuff:

 

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Got all that old grease off of the worm gear. Didn’t help one bit.

 

I spent about 6-hours on it and to keep it short, it was the track-0 sensor yet again. I loosened the screw on it,  moved it back just a hair, and it has been working ever since! Hopefully it’ll keep working this time...

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Do you have a photo or reference that shows how to adjust the track 0 sensor? The diagrams in Dead Mac Scrolls are for 800k drives only, I think. 

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8 hours ago, Crutch said:

Do you have a photo or reference that shows how to adjust the track 0 sensor? The diagrams in Dead Mac Scrolls are for 800k drives only, I think. 


There is a screw behind that piece of linkage I outlined (going through the little circuit board the sensor is mounted to. Loosen that, and the sensor will move back-and-forth allowing for adjustment.

 

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12 hours ago, Crutch said:

Do you have a photo or reference that shows how to adjust the track 0 sensor? The diagrams in Dead Mac Scrolls are for 800k drives only, I think. 

Here’s a better pic of what I’m talking about (not my own pic).

 

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It’s the screw outlined in green.

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Happy to report the floppy drive is still working!

 

Also, I received the other analog board I purchased with the older, smaller flyback and it is working great! No more high-pitched ringing either!

 

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I can’t believe it just worked. Didn’t need any help at all. Obviously, it still needs to be recapped, but otherwise it’s good to go. 

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Got the Sony Test betas running on the 512!

 

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The “Steve sez...” dialog boxes in version 7 are just beyond cool!

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Got the proper mouse for it!

 

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It’s the correct one with the squared connector end. The newer ones work, but having this one makes me feel better! :) 

 

I’m amazed how usable this machine really is. I wasn’t sure if a 512 would be really limited to use or not, and it most certainly isn’t! Pretty much everything I have tried so far works fine on it.  Incredible what all you can do with 512KB!

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Yeah. A 512k was a great leap forward. Back in the day, I remember how a 512k with Switcher and an external drive felt incredible to use after starting out with a single-floppy unitasking 128k.  

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13 hours ago, Crutch said:

Yeah. A 512k was a great leap forward. Back in the day, I remember how a 512k with Switcher and an external drive felt incredible to use after starting out with a single-floppy unitasking 128k.  

I bet a single-floppy 128K can be quite painful! I would like to play with one just to see what it’s like though. 

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