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Macintosh Classic restoration


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Hi folks,

I bought a Mac Classic on eBay recently, as part of my plan to relive some of my youth.  I had various 68k machines in the mid 90s, the only one I ever got new was an Amiga. I was given a Mac Classic free as it was going in the bin, and used it on and off for about 10 years before it started to make some weird noises on boot and i sold it for spares or repair on eBay.  As it always goes with me, when i get rid of some tech, i want it back! so now I have one again :)

 

Luckily this one has the full 4 meg of ram, the one I had before only had the stock 1 meg, which was limiting.  I've cracked the case and the caps on the analogue board look okay (probably aren't but no obvious leaking) but the logic board has badly leaked, and bulging caps in a few places.  a couple of badly corroded traces and very dull solder.

Good new is, the PRAM battery hadn't leaked at all, and looked relatively new, there's a sticker on it that says 2003 so I assume replaced around then, but I'll buy a new one or just leave it out entirely if possible.

 

I'll stick up some photos later today, as the logic board is currently soaking in a bath of isopropyl alcohol to clean it up a little, so I can see exactly what I'm dealing with.

 

Can anyone recommend a source for the capacitors to replace the leaking ones, preferably UK based?  and also, is it worth going tantalum or should i stick with electrolytics?

 

Thanks

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Don't know about the UK, as I am in the USA. But as far as prices are concerned, I seen these two sites have the lowest:

Mouser: http://www.mouser.com

Questcomp: http://www.questcomp.com/Index.aspx

 

And not necessarily for caps, for they got them, but go other parts like connectors-

Digikey: http://www.digikey.com

 

As for the cap type, Tantalums are electrolytic as they are polarized, but the old fashion cans will leak in time, so if you can get the solid state Tantalums, that would be fine. Tantalus come in Surface Mount Technology squares or in round tiny beads with long leads you cut to size. Genie_Mac did his SE/30 with the beaded Tantalums and it looks great! His page of him fixing his Mac SE/30 is here, it deserves a look:

https://68kmla.org/f...ot-another-one/

 

 

BTW - the Beaded Tantalums are far cheaper than the Surface Mounted Squares if price is an issue.

Edited by Elfen
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It's nice to see another British member!

 

I've restored two Macintosh Classic II's and it would be worthwhile to recap the logic board and the PSU portion of the analog board.

 

It would be likely that the capacitors on the logic board have leaked. In my experience the PSU capacitors may have leaked.

 

There are a few tell-tale signs, such as a 'fishy' smell and the AB may look like is has had Coke spilled on it.

 

post-2052-0-14256600-1409837928_thumb.jpg

 

 

When recapping logic boards I prefer to use SMD electrolytic capacitors for that stock look.

 

Where I buy my supplies:

(I am in no way affiliated with any of these people)

 

http://www.bitsbox.co.uk/

 

http://www.ebay.co.uk/itm/Electrolytic-Radial-Capacitors-Various-Values-Voltage-/120953923082?pt=LH_DefaultDomain_3&var=&hash=item1c296a660a

 

http://www.ebay.co.uk/itm/Panasonic-Electrolytic-Radial-Capacitors-High-Quality-Various-Values-Voltage-/111020269027?pt=LH_DefaultDomain_3&var=&hash=item19d952dde3

 

 

As for finding SMD capacitors I usually type 'SMD capacitor' and its value.

 

Good luck!

 

 

 

 

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I use either CPC or Farnell to get my caps (farnell has a bigger selection but has a £20 minimum spend to pay by card, and i normally order £5 - £10 of supplys)

 

I favor stock Panasonic Branded SMD's these days, either that or ceramics

 

And Uni's drives are pretty good, deffinatley worth getting one (I suspect the adapter you have MJ313 may be one of the ones i make and often swap with uni for cool stuff, if it has built in termination it is one of mine :) )

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I'm going to add my praise for Uniserver's 10K drives. I've had one running in my LC475 without a hitch for a year now, and it makes a phenomenal difference to the system as a whole. It's faster than the old SCSI drives and the capacity is, of course, enormous.

 

I actually have two of these drives and I think I'm going to install one of them in my Classic when the motherboard gets back. It'd be good to have partitions for System 6 and 7.1.

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certainly seems tobe pretty high praise for the drives, i think i'll pick one or two up.  I already have plans to expand my collection.  though my next planned acquisition is a powerpc and has IDE drives

I think I'll go with the tantalum surface mount caps for the logic board, as i feel there are only so many times you can solder on a board before it dies, so i might as well reduce the risk of needing to replace any caps in future.

I'll get the usual electrolytics for the analog board though.

Having peeled off the various stickers that were on there, the machine definitely needs a visit from the retr0brite fairy, it's very yellowed, but not evenly :(

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Tantalum surface mount caps are electrolytic but use the metal Tantalum instead of aluminum of its capacitive plates. Things is  electrolytic caps can be wet with electrolytic fluid in them or dry with electrolytic powder in them. Tantalum surface mount caps use the dry electrolytic.


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  • 2 weeks later...

That's all the capacitors on the logic board replaced, and the damaged trace now has a layer of solder over it after having a little clean up with a fibreglass pencil. 

board washed down with 99% isopropanol, then deinonised water, left to dry for 24 hours on a radiator, and it booted first time.  when i can find the ink cartridge for this printer i'll test the serial ports, but ADB works, and so does SCSI and sound.  I'll tackle the analog board soon, and then get the retr0brite out for the case :)

 

now  just need to get hold of a larger drive, and get some disks to reinstall the OS

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Congrats on getting it this far! Like that first pic showed, that analog board caps do need replacing. The sooner the better.

 

Since this is a classic, have you tried booting up with the ROM Drive? It's supposed to come up in System 6.08 when you hold down the Command-Option-X-O keys on start up.

 

Its the only Mac I know that can do this and it is great for Hard & Floppy Drive Diagnostics and systems testing. You can also make an emergency Floppy Boot Disk on it by formatting a floppy disk and dragging and copying the System Folder from the ROM Disk to the Floppy Dsk.

 

EDIT - Sorry, that's not your pic but someone else's. Still the sooner you get it done, the better.

Edited by Elfen
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