Macintosh 512Ke in (not so) good working order.

[lizardb0y]

As mentioned, it all started with a puff of magic smoke. This is the blown filter cap before I replaced it.

Not the prettiest image. Anyway, the replacement went fine, and the Mac powered up nicely.

For a while.

So now I need to order more parts.


I'm writing it up here.

[tezza]

Yea. If one of these old filter caps goes in any of my units, I tend to replace them all while I'm at it. They are a real weakness with these old computers.

[lizardb0y]

Yea. If one of these old filter caps goes in any of my units, I tend to replace them all while I'm at it. They are a real weakness with these old computers.

In hindsight I should have ordered those as well. I don't know why I didn't - probably all the stuffing about and cancelled orders. RS claim to have the replacements in stock, but they said the same about the other caps so I'll call them in the morning. I'll order enough for a couple of spare sets of replacements, and try to do something about the badly corroded battery holder at the same time - it came with the 25 year old battery still fitted

[Carcenomy]

Not knowing an awful lot about early Macs, what is the story with the battery holder etc on the early models, how big was the battery etc? I wonder if I could salvage you up a battery holder from that LC630 board I was about to dump?

[lizardb0y]

Not knowing an awful lot about early Macs, what is the story with the battery holder etc on the early models, how big was the battery etc? I wonder if I could salvage you up a battery holder from that LC630 board I was about to dump?

The early Macs, up to the Plus, used a 523 aka PX21 battery - looked like an overgrown AA putting out 4.5V. I don't think this battery was used in anything after the Plus, and many models had the battery soldered to the board. Thanks for the offer though I just need to make replacement clips for each end of the holder as the originals are so badly corroded they snapped off.

It's almost impossible to find the 523 batteries anymore, so I was planning to use a 1/2 AA 3.6v Lithium and fabricate a shim to fit in the original holder. This reportedly works well.

[tezza]

Out of interest, was the battery in these early Macs just for the clock? I'm assume you can boot a machine quite successfully without the battery fitted?

Batteries in old computers can be a good source of board rot. It's always something I'm aware of when buying an old computer which I KNOW has (or should have) a fitted battery. Thankfully many of my machines are early enough not to have them. Once a year I tend to do a check of all my machines which have batteries included just to check they are in good health.

I wonder how many early Macs have been destroyed by the original battery leaking it's contents all over the tracks and components. ?

[lizardb0y]

Good news. The 512ke powered up flawlessly with the new caps installed, though I still haven't sorted out system disks. I'll tackle that when I get back from Australia next weekend.

Out of interest, was the battery in these early Macs just for the clock? I'm assume you can boot a machine quite successfully without the battery fitted?

It seems to run fine without the battery, but I haven't tried a System disk yet.

Batteries in old computers can be a good source of board rot.

I've been pretty lucky so far. I didn't realize my IIgs had a battery until it had been on the shelf for a few years, and it hadn't leaked

I had a couple of newer machines destroyed from battery leak; an IBM 701 c laptop was trashed.

[lizardb0y]

The 512Ke, Plus and SE all have 400K/800K floppy drives, so I can't make boot disks on my PC. I had a Powerbook 160 which had a dead PSU, and I didn't know if it ran or not. Recently a Powerbook 100 came up for auction locally for NZD 4.50 (approx USD 3) and the seller confirmed that the "screen lit up" and she could move the cursor around. This was enough to convince me that it probably worked but had a dead HDD. On receipt of the PB my guess was confirmed - I've never heard such a bad sound coming from a hard drive, and I've heard a few bad ones in my time.

I was about to try to source a replacement HDD for the PB 100, when I recalled the PB 160 I had sitting "in storage" with a dead PSU. Sure enough, the PB 160 booted fine (albeit with a very bad but legible LCD) once I swapped the PSU. The next step will be getting System 4.1 images onto the PB 160 from the PC, them writing them to fresh DSDD 800K floppies. The sealed boxes of DSDD 3.5" floppies I had put aside turned out to be DSHD, so I still need to find some blank, reliable DSDD floppies. I found a shop online which sells new boxes of floppies, but can't find it again! Doh!

[Carcenomy]

Hmm, could you use high density media to at least get it going? I know Amigas are pretty tolerant of formatted high density disks... I can't imagine the Mac being too surly about it.

[lizardb0y]

I have to write the media on an HD drive, so I'm not sure that it will let me format DD on an HD floppy. I should get some time this weekend to poke it with a stick and see what crawls out. I have another plan that invloves SCSI Zip drives and the Plus,

And I found this again:

http://www.oldsoftware.com/floppy_disks.html

They're a bit pricey though.

[Carcenomy]

Remember of course the magic trick that the Amiga guys use when using TransDisk to get data to/from a PC - tape over the HD hole on the floppy so the drive's sense pin can't determine that it's HD, which allows formatting in DD formats.

[lizardb0y]

Success!

I had a Macintosh 512Ke with a 800Kb floppy drive and no 800Kb floppies. What could I do?


After finding myself a Powerbook and power supply that worked, I also obtained a SCSI adapter for the strange HD30 connector on the back of the PB. I coupled this with a Zip Plus drive (and a Zip USB for the PC) which let me easily copy files from the PC to the PB (see what I did there?). With Disk Copy 4.2 this let me write 400K, 800K and 1.44M floppies of all formats. Yahoo!! Macintosh System files were downloaded from Eric Rasmussen's <a href="http://homepage.mac.com/chinesemac/earlymacs/">web site</a>, copied to the PB on a Zip disk, and written to floppy. This actually took me the better part of a day to get working properly, with creator IDs intact. I kept getting binary files on the Mac that wouldn't be recognised Disk Copy, but as long as you copy the .sit and use StuffIt on the Mac to uncomporess you're OK. I rummaged through my various boxes of "parts" and located some MSX formatted 3.5" DSDDs that I wouldn't miss.


Finally I had me a System 4.1 floppy. I took it through to the workshop, power up the 512Ke, and inserted the floppy. Soon enough I was greeted with this:


So now I have a working 512Ke. The next step will be to tidy it up a bit, then get some photographs.

[tezza]

Good one Andrew,

I can relate I as had to first fix my Lisas, then go through a similar labourious process to create 400k floppies in order to load software. Luckily I had a Classic II with an external 800k drive. My biggest headache was getting the sit files from the Internet onto the Mac Classic II through my XP PC, but I found a piece of software called Transmac which did the job.

Having grown up with PCs though, it was a big learning curve. SIT files, HXQ files, and Resources forks were all a little new to me. I should be right now though, if ever I get hold of a Mac 128!

[XOR]

I'm glad you got the caps fixed in your system.

IMO Radio Spares is next to useless. Their inventory is grossly overpriced and they hold very little in stock within NZ.

I'd recommend that you look seriously at using Farnell. I've been ordering components them for the last five years and they've been a joy to deal with.

[lizardb0y]

I'm glad you got the caps fixed in your system.

IMO Radio Spares is next to useless. Their inventory is grossly overpriced and they hold very little in stock within NZ.

I'd recommend that you look seriously at using Farnell. I've been ordering components them for the last five years and they've been a joy to deal with.

Over the years I've dealt with RS (they used to have a store in Dunedin), Farnell (Now Element 14) and the other more consumer focussed outlets like David Reid, Jaycar and Dick Smith Electronics (when they still did hobbyist gubbins). In this case RS listed the exact part replacement I needed, though it turned out not to be available. I ended up getting an overpriced alternative part from Jaycar because they sold by the unit and shipped overnight.