Classic Mac Restoration (First Post)

[Benno]

Hi all

First post on this forum which I stumbled across searching for information, was an early Apple user from the first Apple II, was lucky having a mum as a school teacher and the Computer Person from the school (as they were called in the late 70's early 80's) live across road, so spent my whole weekends in his office playing games like Hitch Hikers Guide etc was there with the birth of the 1984 MAC and we used to have one at home anyway

Anyway I have had a Mac Classic siting on my shelf for years which I salvaged even further years ago with an idea to restore.

Well finally pulled it apart the other day hoping the battery had not leaked and lucky me it has not, so that has been removed and a new lithium 1/2 AA battery installed for now.

So checked all boards for any visible damage and appears ok suspect the caps have leaked on the AB board though, turned it on....nothing then a clicking sound and the screen was showing a horizontal line but jagging with interference.

So have now ordered all the caps for the AB and will replace them all, would someone be able to tell me what caps are needed for the LB please

I will post some photo's soon, great forum, enjoyed ready through the tribulations and triumphs hope to add!

 

[cheesestraws]

(oops, hit post before I was ready)

Welcome to the forum, Benno!

For LB caps, the guide I used is here:

Macintosh Classic - Recap-a-Mac

Not only is the Macintosh Classic prone to leaky surface mount electrolytic capacitors, it’s also prone to battery damage. The particular brand of...

recapamac.com.au

Note that because I'm worse at soldering than he is, I had to get the next physical size of capacitor down - same voltage and capacitance, just one case size down.

 

[Benno]

Thanks @cheesestraws the actual original caps look ok on the LB but looking through posts this may be a thing, I am hoping the logic board is ok but after reading through previous posts may be an issue

 

[cheesestraws]

Yeah - at this point, on those, you're basically going to have to replace them. They're very leak-prone - and I mean actually physically leaking, not electrical leakage here.

 

[Benno]

Here are the photos, case is a bit grubby think I will retro bright it once I get it running

 

[Benno]

And the internals, the AB looks the worse, the caps on the LB are intact and the board actually looks ok, the original battery was still in there with no leakage

So just waiting on caps for both boards will replace all the AB first and see how that goes.

 

[cheesestraws]

You can retrobright it if you want to, but you'd be surprised by how well these come up with a bit of washing up liquid and elbow grease. I never both retrobrighting mine - I don't mind old things looking old - but I do give them a good wash, and they are much better for it.

 

[Benno]

Thanks I will wash it first and I actually don't mind a bit of patina, so might take your advice on leaving its at that the retro brighting looks to be a bit of a pain as well, the main thing is to get it running.

 

[Byrd]

Welcome Benno, the case looks pretty good, it'll come up well dunked in some water and dish soap + microfibre cloth.

Classics have horrible ABs, yours not booting will most likely need the optocoupler replaced, along with all caps. The motherboard caps look OK but you'll find they will have leaked underneath and the longer you leave/use it will result in more damage eventually.

 

[joshc]

The problem with retrobrighting is how easy it is to damage the case. It’s very easy to cause spotted bleaching, the wrong colour, etc. it also weakens the plastic as far as I know, and the yellowing will return. It’s best to just clean them with a sponge / soapy water and leave it at that.

 

[Benno]

Welcome Benno, the case looks pretty good, it'll come up well dunked in some water and dish soap + microfibre cloth.

Classics have horrible ABs, yours not booting will most likely need the optocoupler replaced, along with all caps. The motherboard caps look OK but you'll find they will have leaked underneath and the longer you leave/use it will result in more damage eventually.

Thanks would magic eraser be too harsh on the case? and yes I have the caps ordered for the LB, are you able to tell me the part number for the optocoupler please. I don't have one of them is it CNY75GB.

Also another for not retro brighting, so be it ( I'm glad as I really didn't want to go through that)

Thanks for all the advice and help so far I am sure I will have a lot more questions, I am already looking for another one

 

[cheesestraws]

Also another for not retro brighting, so be it ( I'm glad as I really didn't want to go through that)

This is your computer - you can enjoy it how you want to enjoy it . If you don't really want to retrobright it, then there's no need to. If you do want to, you can try it.

Wrt the logic board: it does look like fluff has got stuck to the capacitor legs in some places, which is a sign that fluid has been leaking out a bit. So yeah, you do want to swap those. And agreed; I'm afraid the analogue boards in these were built to be cheap and "good enough", so troubleshooting them can be a bit of a pain.

 

[Kouzui]

When it comes to retrobriting - I've actually just set my stuff outside for a day or two and it reverses the yellowing significantly, no peroxide required. I agree with the other posts saying to give it a good scrub down, though, since it really does make it look a lot nicer (and maybe good enough to not need to retrobrite).

 

[joshc]

When it comes to retrobriting - I've actually just set my stuff outside for a day or two and it reverses the yellowing significantly, no peroxide required. I agree with the other posts saying to give it a good scrub down, though, since it really does make it look a lot nicer (and maybe good enough to not need to retrobrite).

There have been case studies/examples where thats been done and the yellowing has come back even worse than before, so I'd still say its risky.

 

[LaPorta]

Magic eraser sure gets off the grime...but it also takes off the semi-gloss sheen and makes the case dull.

 

[Benno]

Bit of an update, I received all the caps that are recommended plus all the others for the AB, so did the recommended ones first, ended up with the wobbly checkerboard I was happy to get this point. At this point measured the 5 volt rail and 12 volt and was only getting 4.04 and 10.04, so decided to do all the caps on the AB board (still have not done the optocoupler), so a few reboots and get just a horizontal collapse line on the CRT and the volts are still measuring low.

So should I go the optocoupler next or have I damaged something going from checkerboard to horizontal line, when I changed the rest of the caps pics attached

 

[Benno]

Oh yeah I turned PP1 to max and didn't make any difference

 

[Benno]

Ok was a bit frustrated over this as going from the chequerboard to the horizontal line seemed a step backwards, so spent countless hours reading numerous threads to try a find something, besides ordering a optocoupler, I decided to go over the board again and trace back from the where the yoke connects to the board (the 4 pin plug) and yes I had a broken trace, so I made a small jumper, turned it on and back to chequer board.

Ok so thats a start go, I decided to leave it on for a few minutes, well it was restarting, but I suppose eventually the 5 volts rail got up to enough to boot, it is measuring at 4.75 ash picture below point, is this enough? or do I need to increase it more?

And the hard drive works as well, I still think it wants to restart so I suppose I really need to stabilise the voltage, well that the next step, pretty happy to get this far

 

[bibilit]

under 4.85 is not enough, above is fine,

 

[Benno]

under 4.85 is not enough, above is fine,

Thought so thank you, waiting on a optocoupler to see if that fixes the voltage, and also try the ohm pot ( ordered a new one of those as well)