Classic Restore

[erichelgeson]

Hello all,

Another restore thread (I like following these for other people, so I hope you do too)

Picked up a Mac Classic (1) from craigslist for $40 (they were asking $100, but accepted my offer right away, worth it to haggle - untested, dirty, yellow:

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Had some interesting stickers/post it note (that must have been on there for 20 years, seems "original" and survived all this time lol)

You can see too how yellow/dirty/discolored the case is here too.

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Inside was "ok" lots of dirt in the fan, but just a bit everywhere else.

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Motherboard has expected cap leakage - along with a memory riser card which I've never seen in person, neat!

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I cleaned the motherboard with 99% IPA - let dry and booted up, but had some really "weird" results!

• First power on i heard some crackle from the speaker, but nothing. Flipped the switch a few times, same thing.
  
• Then I left it on for a second and all of a sudden the HDD spun up (scaring the crap out of me)
  
• Then I see a faint checker board pattern
  
• Then a "soft" reboot
  
• Then the normal screen but "wavy" eg, the left/right side of the screen was waving in and out
  
• The screen got brighter and brighter as time went on, then I got the question mark
  
• As time went on the waves slowed and stopped.
  
• Internal fan randomly started after a few minutes, again startling me!
  

My assumption is the analog board needs a recap. Something probably got warm enough to work and eventually was able to boot up.

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Next Steps:

• Recap Motherboard
  
• Recap Analog board
  
• Service floppy (wont eject)
  
• Find a solution for HDD, it sounds like it's on it's last legs
  
• Clean outside and try my 40% bottle of hair product method
  

I can say after working on the CC and SE/30 the past week, the insides of the Classic 1 are much easier to work with.

 

[desertrout]

Nice find! FWIW I'd say your instincts are correct - recap of logic and analog boards. Keep us posted!

 

[erichelgeson]

Caps Removed very cleanly from board. Used hot air gun. Hard to not heat the plastic power adapter on the motherboard. Also retinned a leg on the Y1 that was very dark. Still need to pull Analog board out to get stock of caps needed for it.

Might as well service the floppy drive tonight too - ~5 superficial rust spots on it, maybe some cap leakage, cleaning up nicely though.

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[cheesestraws]

I love these threads and the photos.  Thanks for posting them!

 

[LaPorta]

I found that a good way to protect the plastic connectors and components is to cover them liberally with aluminum foil. A very good insulator for the heat (it is metal, but it deflects the air and won't get too hot in and of itself).

 

[bibilit]

Analog board issue for sure. 

Time for new caps and diodes at least. 

Price is is fair for the setup

 

[erichelgeson]

Is there a list of the caps needed for the analog board? There are so many on the board!

Console5 has a kit, but doesn't list what is included https://console5.com/store/macintosh-classic-and-classic-ii-analog-pcb-cap-kit-for-p-n-630-0525.html

Branchus Creations has a video on it, though it's for the international version.

(Also if the boards are the same as the classic II I can test everything in my II to rule things in/out.)

@LaPorta good idea - I did put some heat tape on there, but not enough i guess. Very minor discoloration, but will try your method next time, or a combination!

 

[LaPorta]

I’ll send you a copy of my Mouser part list. Be forewarned: it appears that 2-3 of the caps changed over time (not just ratings, but whether they are there or not) depending on the analog board revision. Logic board is almost the same (though there were different ROM size revisions).

 

[rplacd]

+1 to LaPorta's note – there are two revisions of Classic AB, and I used this helpful diagram (from the very useful "Technical Procedures Macintosh Family") to figure out which was which:



Welcome to Classic gang gang! These are so, so much easier to work on than SEs and SE/30s. Dare I say these are the ultimate compact Macs because of their simplicity.

 

[erichelgeson]

Thanks! Interesting diagram. My yoke cable is A, has the "square" component next to it (not sure what it is) but has an Oval Hole? So I'm guessing A, but that oval hole is throwing me off

It says:

> Note: There are two versions of the Macintosh Classic power/sweep board: Rev A and Rev B. These two power/sweep boards are functionally equivalent but are not interchangeable. The Macintosh Classic II always contains the Rev B board.

So if my Classic 1 is indeed an A - I will not be able to test it with my Classic 2's AB.

 

[rplacd]

So if my Classic 1 is indeed an A - I will not be able to test it with my Classic 2's AB.

Not necessarily – the power connectors on the physical AB are different. But the power connectors that plug into other boards are compatible between the Classic and Classic II – after all, you can upgrade a Classic to a Classic II by swapping the logic board.

 

[erichelgeson]

Ahh I see, I read that backwards then. Finally putting in a mouser order for caps tonight.

 

[LaPorta]

All of that is true, but that wasn’t even what I was referring to. I worked on two different classics, both with Rev A style boards, that had a slightly Different capacitor layouts. It was odd, but it happened.

 

[erichelgeson]

@LaPorta
Thanks for the list via email. I'll share a cart after I order.

Removed all caps from the analog board and validated all the values. Used solder sucker, worked well. No real issues besides getting heat on bigger pads.

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[mraroid]

Good workmanship!  Love the photos.  I buy all my caps from Mouser as well.  They have reasonable shipping charges.  And I like the fact that I can buy 1 cap, or 100.  They have been a good company for me. 

mraroid

 

[erichelgeson]

Here's the mouser cart with locations, though 2 of them are out of stock... Since this is my first time doing a direct order could someone help validate these replacements? (or offer their suggestions)

Current Cart:

https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=48e4badd71

1000uF 35V Out Of Stock

https://www.mouser.com/ProductDetail/667-EEU-FS1V102LB

Replacement?

https://www.mouser.com/ProductDetail/Wurth-Elektronik/860040578014?qs=0KOYDY2FL2%2Fruv7wsM5kuA%3D%3D

470uF 25V Out Of Stock

https://www.mouser.com/ProductDetail/710-860020474014

Replacement?

https://www.mouser.com/ProductDetail/Wurth-Elektronik/860010474013?qs=sGAEpiMZZMukHu%2BjC5l7YRTxnIahtzp%2Beh0UIgn8eFo%3D

Thanks!

 

[LaPorta]

Any cap of the same specs of capacitance, and the same voltage or higher is ok, provided that the cap isn’t craZily tiny...you’d run into heat dissipation issues. You can look them up right there on mouser

 

[erichelgeson]

Right - I did look them up and provided what I think is a valid option - but the comment "crazily tiny" are what worry me. I'm not an EE - I don't know what I don't know I'm learning and want to know more!

 

[LaPorta]

I’m not either, just average joe fixing his machines. What id do is look up the ones you were going to order and see the diameter and length on the website. As long as they are roughly the same they’ll be fine.