Macintosh 128k replacement went (almost) perfectly!

[rushfan82]

Picked up a boxed 128k a week or so ago and it came with both its original board and a spare that had been upgraded to 512k. I ordered some new tools and some sockets and 4164 chips, and after a few hours and some minor troubleshooting, it works great! This is my first time replacing something like this so I'm super proud of myself. Going to do the analog board next!

 

[tattar8]

Nice!

So you downgraded the 512k back down to 128k?  I just got my hands on a 128k that has also been upgraded, and trying to figure out what I need to do to reverse the upgrade.  What did you have to do?

 

[bibilit]

Not just ram chips...

The upgraded boards i have seen before have been modified in a way or another (cut traces, 74LS253 chip added...)

 

[tattar8]

On my board, the 74LS253 was installed on a little PCB attached to a header.  I just removed it and used a jumper to jump the two pins that corresponded to the cut trace.  Now as far as the Mac is concerned, it's back to only having 128k.

 

[Crutch]

Nicely done. I am ambivalent about my 128k. I love the original non-upgradedness of it and that whirring grinding 400k drive sound. But my goodness it can’t run very much software. Part of me thinks I should just grit my teeth and pop in a 512k board so I can get a bit more use out of it!

 

[bibilit]

Nicely done. I am ambivalent about my 128k. I love the original non-upgradedness of it and that whirring grinding 400k drive sound. But my goodness it can’t run very much software. Part of me thinks I should just grit my teeth and pop in a 512k board so I can get a bit more use out of it!

the original board is pretty useless and if you are limited to the internal drive only, even more.

Was already true when new, that's the main reason so many were upgraded at some point, from a 512k board swap to the Plus upgrade later on.

Today, for the sake of originality, and price value, the downgrade is the way to go.

As so many Pluses were produced, and still are relatively cheap (compared with an original Macintosh) having both of them is not a nonsense.

 

[PB145B]

Part of me thinks I should just grit my teeth and pop in a 512k board so I can get a bit more use out of it!

That's exactly what I'll do if I ever get an original Mac (keeping the original board of course). I like using my computers, so I would want it to be usable. Same way I wouldn't keep an IBM PC with 128K. Just too limiting. That being said, the difference in cost is not worth it to me just for the badging, as you can still get 512ks (especially 512kes) fairly cheap sometimes. And honestly, I quite like the Macintosh 512k badging anyways, but if I ever see a cheap original Mac, I'd love to have one.

That being said, I can certainly understand and appreciate why someone would want it 100% original.

 

[Brett B.]

My 512k was upgraded to Plus specs, I'd probably undo that if I ran across a 512k board/400k drive but it's just parts swapping at that point.  I don't know if I'd go as far as undoing permanent upgrades just to downgrade... what's done is done is my MO.

 

[rushfan82]

I have two boards for it, one is an upgraded 512k board from another computer, the one I fixed is the original one to the machine.