I’m thinking that the IT department at those schools may have mixed & matched parts to keep them working… at the time, these were VERY ex$pen$ive…

@Epictronics1

Жыл бұрын

Yeah, you're right. Maybe the Harvard IT guy put the wrong back cover on this MAC? The only thing I didn't manage to date was that cover. Hopefully, someone will help us date that part too. I'm sure there were some minor differences that someone out there knows to identify it

Apple started badging the “Macintosh” as “Macintosh 128K” around September of 1984 I think because that’s when the 512k released. Those specifically labeled models are rather rare because most people just bought the more capable 512K or upgraded their original model to have a 512k board.

@Epictronics1

Жыл бұрын

Ok, so according to that, this MAC should have had a 128 badge, since it was made two months later?

For rusted steel parts you might like to try electrolysis. It's pretty easy to do; you just need a big plastic bin, a car battery charger or adjustable power supply, washing soda from the grocery store, a few wires, a chunk of iron or steel, and water. There are tons of guides online. If it were me I would certainly do that before chemical treatments. I save those for stuff too big to fit in my improvised electrolysis tank. For those playing along, you should not leave primer exposed for long periods of time. It certainly better than nothing but eventually water will creep in from the air and restart the corrosion. Always cover your primer with a top coat before the job is done.

@Epictronics1

Жыл бұрын

Ok, I didn't think bare primer would be an issue in a pc that's always indoors, but thanks for the warning. I'll apply a top coat before I put it back in. I actually have a nickel plating kit with all the different baths, including acid. It would have been perfect for this project, but it's in storage for the same reason as my sandblaster equipment :/

@Epictronics1

Жыл бұрын

@Mr Guru true, but it would look really fancy if nickel-plated :)

@Hitek146

Жыл бұрын

Came here to say this. ***Primer alone does not stop rust!***

@Epictronics1

Жыл бұрын

@Mr Guru haha. You know, that thought actually crossed my mind while I was writing that post. An acrylic case with a high gloss polished steel frame would look pretty damn neat :)

@Epictronics1

Жыл бұрын

@Mr Guru Man, that would have been so cool. My BMX was just plain silver. I actually have a nickel-plating setup. I use it when I restore my vintage bikes. Unfortunately, it's in storage because I turned my garage into a studio. The only difference visually between nickel and chrome is the color temp. You would have to look very closely to see the difference. Nickel is slightly warmer than chrome. If you hold them close together, chrome looks slightly bluish in comparison. I'll see if I can find a picture of some project and email. If the kit was out I would have used it on the chassis but I wouldn't bother polishing it of course

Nice job with the rust. The machine was lucky indeed, considering that the damage wasn't too severe.

@Epictronics1

Жыл бұрын

yeah, I thought we would find a battery-bombed mobo in that machine

Very interesting. I really enjoy these old machines being rescued. Primer is not a good top coat because it's generally formulated to be porous so that the top coat can adhere as well as possible. This means that moisture can also get to the steel and cause new rusting. (I see that someone has already mentioned this. Oh well.)

@Epictronics1

Жыл бұрын

I ended up respraying it in a white paint I had laying around :)

I have one from the University of Chicago business school (then the GSB, now Booth). Worked in IT there for 15 years, one of my first months there a group of old machines to be tossed was sitting in the hall by my office. In there was a Mac Plus that I rescued. I know the office it came out of, and the user is now a Nobel winner.

@Epictronics1

Жыл бұрын

cool :)

Yes, this kind of video is interesting. There are so many 'marginal' computers out there that can be saved, it is important to show some techniques that might restore them to operation. The 70s-80s were an amazing time for personal computers, it would be sad to see those computers disappear from existence. Thanks for all your good work. Cheers!

@Epictronics1

Жыл бұрын

Thanks. yeah, it's been quite the trip to see how personal computers have gone from "toys" to every man's necessity. I'll keep restoring these historical gems, cheers

AFAIK the "red stuff" is dielectric grease. It prevents arcing from the yoke HV feed.

@Epictronics1

Жыл бұрын

Thanks, that's what I suspected it was for. I did a google search for dielectric grease and it appears to be the same as Silicone grease? At least according to wiki. Do you know if I can use regular silicon grease? or can you recommend any specific products? I've had arcing from a tube ones and that was quite the bloody show. Don't want that experience again :)

@PgWsLRoiEeyZFdXRWGMPNyiFrWpmSo

Жыл бұрын

I’ve used Permatex 22058 dielectric grease before for this purpose. I think somebody on 68kmla recommended it.

@Epictronics1

Жыл бұрын

@@PgWsLRoiEeyZFdXRWGMPNyiFrWpmSo Thanks

@ChristopherGaul

Жыл бұрын

@Epictronics your local auto parts store should have something suitable as it's used on spark plug boots. I think the Permatex brand makes some.

@SanguineBrah

Жыл бұрын

@Epictronics This isn't quite right. The red stuff is a high voltage insulating lacquer, also referred to as corona dope. The lacquer is applied to the tube around the anode cap to prevent arcing. Dielectric grease is used on the cap also but it's there to create a good seal of the cup to the tube - that's a separate thing.

Looking forward to Pt2. That disk drive looks like at the very least, needs a thorough clean and lube.

@Epictronics1

Жыл бұрын

Let's hope it just needs cleaning and lube. I found a spare drive that we can use for troubleshooting if needed

For rust, check out some of the car restoration KZreadrs. They typically use rust converter chemicals.

@Epictronics1

Жыл бұрын

I'll check, thanks

You're fine with "it's for both machines." A native speaker would hear it as "boards of this type were used in both types of machines."

@Epictronics1

Жыл бұрын

Thanks

That was a really great video. I look forward to part 2

@Epictronics1

Жыл бұрын

Thanks :)

That cleaned up lovely 👌

I do have one with original printer and trackball

I'm so glad you got to this machine in time! It was super lucky that the corrosion didn't get to any of the major components. Shouldn't even need a recap since it's from before the capacitor plague. Besides the Rifa cap, of course.

@Epictronics1

Жыл бұрын

Yeah, Those caps probably won't leak for another decade. But since we are going to replace the RIFA and the bipolar cap, we might as well replace them all on this project.

Now on patreon.com/Epictronics This video is Part 1. Part 2 Here: kzread.info/dash/bejne/pKGXsKuSZ8mthbA.html Part 3 Here: kzread.info/dash/bejne/X5ODqrKAqZm0pZM.html

Very much love your content! If there was one thing I could wish for, it would be longer videos! ;)

@Epictronics1

Жыл бұрын

Thanks :)

If you look close enuff the "missing" number is a 2, no other number has the straight line at the bottom of the number like "2" does.

@Epictronics1

Жыл бұрын

I think you're right. late 1984. That seems just about right. We'll crack it open and check against the date codes on the chips. Thanks

@kaliban4758

Жыл бұрын

​@@Epictronics1 you are welcome

the red stuff is likely some sort of high-voltage dielectric grease.

@Epictronics1

Жыл бұрын

Someone commented that the red stuff is lacquer. Apparently dielectric grease is applied in addition to the lacquer

I'm always down for weird Macs.

@Epictronics1

Жыл бұрын

weird MACs are fun : )

I'm pretty sure that's a "2" at 3:45

Small hex keys are good to use for floppy or other force ejects.

@Epictronics1

Жыл бұрын

Why didn't I think of that. That's useful, thanks

The cord that you weren't sure of is typically found on CRT displays of either AIO's or higher quality monitors. My guess would be that the cord is to keep the two boards from shorting each other out, given the Mac's tight enclosure. Fortunately some of their later models that had a CD-ROM option switched to a sled assembly, which made this a lot less dangerous to maintain.

@Epictronics1

Жыл бұрын

I'm not sure I understand, do you mean the grounded coil?

@richardestes6499

Жыл бұрын

@@Epictronics1 probably. I don't know every last detail. I've only disassembled them for e-cycling purposes, so to me, wiring is wiring.

Nice work! I need to restore mine from an aesthetic point of view as well! I'm a bit concerned about using paint (also the PS/2) as there are so many point where the chassis is electrically connected to other parts. One solution is to leave bare parts as you did of course. Try Citric Acid for the chassis - it's cheap and works like a charm. But you still need to brush it a bit at the end, just to smooth up the surface a bit. That was a lucky Mac indeed. The battery bombed but it missed its target! :)

@Epictronics1

Жыл бұрын

Yeah, I was sure "Harvard" was swimming with the fishes when I open that case! Great surprise that the battery missed! I'll try citric acid on the next project, Thanks :)

@tony359

Жыл бұрын

@@Epictronics1 How come all my computers never work well out of the box? :D Well, it would be very boring if they did though! That Mac I repaired didn't have a single component in good working order! MoBo, Analogue board, CRT, Floppy and HDD were all faulty. 100%. Amazing. The PS/2 is proving to be another "less common" repair too :)

@Epictronics1

Жыл бұрын

@@tony359 Haha, I actually don't what I would do if I didn't have stacks of faulty computers : )

@tony359

Жыл бұрын

@@Epictronics1 When I collected those Macintosh, the seller had a garage full of them. At some point he insisted and wanted to give me a working one "where's the fun in that" I replied. "That's boring, you plug it up and it just works?" :)

@Epictronics1

Жыл бұрын

@@tony359 haha, those machines end up being used for spares :)

a little trick I learned a while back with capacitors is to unplug the machine, but then turn it on. Turning it on should discharge any remaining power. In a modern pc it will even turn the fans a bit. Not a full revolution, but maybe like a 1/4 turn. That should get everything safe.

@Epictronics1

Жыл бұрын

That's useful, thanks :)

@michvod

Жыл бұрын

This won't do anything in Macintosh's case, as the on/off switch is essentially the mains switch and does the same as unplugging it. Your advice is fine for devices made in this century though as most of them have soft power on switches

@awilliams1701

Жыл бұрын

@@michvod ah ok. I wondered if it would have the same effect with a CRT, but that makes sense.

I wonder if they had specially binned RAM?

@Epictronics1

Жыл бұрын

RAM chips were silly expensive in 1984. Apple had planned to make the MAC with 512k but ended up selling it with only 128 in the beginning because of the high price

Looks like the analogue board might say "sp1706" with a scored "7"

@Epictronics1

Жыл бұрын

Hmm... I would expect a year and a week number

@brianclimbs1509

Жыл бұрын

@@Epictronics1 Yes, strange. Maybe the 130th day of '86?

@Epictronics1

Жыл бұрын

@@brianclimbs1509 Well, the serial number, the ICs, and everything else is older than week 47 of 1984

You might need to burn a newer version of the ROM to use an external 800k drive with those; IIRC you need the ROM that shipped with the 512ke; the earlier versions didn’t have the required driver in it.

@Epictronics1

Жыл бұрын

Now that you mentioned it. I recall reading someplace that REV A was replaced because it only supports the very early SONY OA-D34V-22. An upgrade of the ROM totally makes sense. I'll do some reading and burn some ROMs, thanks

Nice job. try galvanizing the chassis

@Epictronics1

Жыл бұрын

I guess that's how it was originally done. Sounds like an expensive thing to do for a project like this though

4 minutes in and I am thinking someone swapped the cases.

@Epictronics1

Жыл бұрын

It's quite possible. I don't know how to date the back cover, aside from the badge. All the other parts can easily be dated. We could swap them but I don't like the idea of putting that broken case on the early MAC. If they are identical, I guess we could swap the badges instead

The reason the Macintosh produced in 1983 has a 512k badge is because Apple provided a 512k upgrade kit for buyers of the original Macintosh for $995

@Epictronics1

Жыл бұрын

yeah, that's possible. We'll take it apart and see what we'll find inside. I wasn't expecting Apple to include the badge though

"Halfway out"? Right, hardly!

@Epictronics1

Жыл бұрын

Well, no, perhaps not the correct word to use. It didn't show too well on camera but the mechanism inside the drive had lifted the diskette to the position where it should have just popped out

Wow, I wonder how that disk got stuck so hard!

@Epictronics1

Жыл бұрын

yeah, that's a first for sure. We'll find out in pt2

@HelloKittyFanMan

Жыл бұрын

@@Epictronics1: Cool, I'm excited to see it.

@michvod

Жыл бұрын

@@Epictronics1 The grease in floppy drive mechanism dries up and turns to strong glue. Never force a stuck floppy out of these drives, you will destroy the heads in some occasions due to that

@Epictronics1

Жыл бұрын

@@michvod Ok, thanks. We'll clean out that old grease in pt2

I would buy a broken one for 50 euros

WoW ... i've thought only ASMR could makes me sleep... And after the minute 3:00 i've realised i was wrong 😂 😂 😂

@Epictronics1

Жыл бұрын

Thanks for the honest feedback :/

@Octamed

Жыл бұрын

Was a good paced video for me?

Ugh, why would try to force the mechanism to eject when it's obviously quite jammed up? The plastic gears in the eject mechanism are delicate! You should take it apart, clean, and lubricate it before doing anything like that.

@Epictronics1

Жыл бұрын

I will do just that in part two. I have spare gears at hand if needed.

@gordonshelby765

Жыл бұрын

@BestSpatula wtf u talking about, thats the ejector pin, u make it sound like the gears are made of tissue paper. worry about your own stuff

@BestSpatula

Жыл бұрын

@@gordonshelby765 he applied power with the mouse button held down which forces the mechanism in the drive to eject.