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This week I am working away from home and I found an ad on OfferUp with someone selling a Mac 512K for $10 - As-is/Parts Only. When I picked it up, I saw it was a 512Ke model and had a nice little SCSI port on the back over top of the battery cover! SCSI upgrade inside maybe? Turns out a 10 year old kid was selling the machine. He offered me a huge box of Mac software and manuals (all original, no copies) with the machine, and I felt like showing him that this type of generosity was a very big deal, coming from a young kid. So I gave him an extra $10.

Got to my hotel, and the first thing I did was open up the battery cover and remove the battery - just a slight bit of green leakage. A bit of ISO 91% and we were good there. I opened up the case, and promptly found that there was a processor socket installed and an upgrade card that had 4 30pin RAM sockets filled with two 1mb ram sticks. This machine was the cleanest vintage Mac I have ever opened!

 

After I did a quick wipe down with the 91%, I put everything back together and inserted a 4.1 system disk that I had made before leaving the house (you know, just in case I ended up buying the machine.) It booted up to the desktop with no issues at all and ran fine. I do not currently have a working keyboard or mouse so all I could do is power it back off via the switch. The seller had told me that the machine only boots to a 'Sad Mac screen' so I was feeling that good karma coming back to me in a big way by this time. The second night in the hotel I powered it up and let it sit there for about 30 minutes. It started to get fairly warm on the side with the power circuitry and then the screen started doing some strange things. I rebooted it with the switch and it booted to the 'Welcome to Macintosh" screen and then started to glitch again. I powered it off for the night. I am guessing that there are a few capacitors/etc. that will need to be replaced on that board. Aside from that, it was upgraded to the equivalent of a Mac Plus and has 2mb of RAM in it. I think it is salvageable and should make a great addition to my collection. With no hard drive, it will run all of the apps/games that do not run well on my SE, mostly due to the fact that the SE has 7.1.1 on it. Dark Castle comes to mind. It wants to run on System 6, so has to be booted from floppy. This will be a great machine for such programs to run on.

 

Where would you guys look first for that overheating issue? I do not see any bulged caps, but of course, they still could be bad.

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Analog board may need to be recapped.  Try looking for any obvious bulging or leaking caps.  Also, the original 128k & 512k had heat issues in general.  Several companies sold internal and external fan solutions to help cool them.  Kensington was a major manufacturer for them.  You can probably find a Kensington System Saver for cheap (Mac version.)

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I plan on opening up the case tonight and inspecting all of the caps. Aside from that, I can take the screws out of the case and then letting it heat up again and then checking it with a Flir thermal scope to find the hot spots. I don't have the Flir scope with me, so I will have to do that job when I get back home.

When I seen the SCSI port, I figured that someone had soldered an expansion card to the logic board somehow, but I never even knew that it was possible to upgrade the RAM and everything like this.

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26 minutes ago, markyb86 said:

What the heck is a 10 year old kid doing meeting people off of the internet??? 

I agree. His mom was the one with the account on OfferUp. When he got out of the car, I was shocked, then she got out and explained that she had listed it on his behalf, to protect him from online predator type situations. I thought that she did a good job. I didn't even know it was a kid until I met them both at the public library.

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I powered the machine on again last night, and (since I have no working input devices) I just let it idle. I was working on setting up my new phone and I forgot all about it for over an hour. It ran fine, did not heat up and did not show any glitches in the screen or video at all. Perhaps the glitches the previous night were caused somehow by me trying that keyboard that seems to be DOA? I'm not sure how that would cause overheating, but time will tell.

When I get back home, I'll round up a working keyboard and mouse and give it a proper test.

 

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Edited by jefframsey
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