Recapping a Classic I

[Scott Baret]

I had originally posted this in Trag's trading post thread, but since both he and I believe it would find a larger audience here, I figured I'd re-post.

I have a Classic I, manufactured in August 1990, that I'm looking to restore for the long haul. I'm not the most experienced solderer on this board, nor am I a foremost expert on caps themselves, so I'm looking for advice/guidance here and will be sending the board off to another forum member for the soldering part. (I'll perfect the art of soldering some day, but right now am too busy educating future generations; I figure I should learn if I want to keep all my older Macs in top shape but just need to find the time to do so).

I looked up the caps and found nothing on the original Classic, just the more popular or more trouble-prone models. Looking at Trag's list of caps for sale and my Classic board, my goal was to come up with a list so I'd know what to order.

Examining the board, I see the following, all surface mount caps:

-Four 47/16 caps near the analog board connector (labeled as C5 through C9)

-Two 47/16 caps near the sound chip (labeled as C1 and C2)

-A 47/16 cap near the reset button (labeled as C4)

-A 1/50 cap (which will be replaced by the 1/35 cap as stated in the previous post) next to C4 (this one is C3)

Can anyone verify these as correct? Are there any additional caps I'd need? Does it have any axial caps? (I have included a picture of my board below; it's an iPod Touch photo so I apologize for the lower quality).

Also, the board has some dark gunk on it near J8 and especially around C8. Is this cause for concern? Should I use another Classic board instead of this one? (The big problem with this particular board is a lack of sound; video problems are also an intermittent issue). I'll probably run it through a dishwasher or a shower on my next day off.

The board in question has not been used since 2009. At that point, I replaced it with another Classic board from a discarded computer. This one works fine but does emit the fishy smell associated with bad capacitors. The substitute board is another candidate to be re-capped, although I'd rather send off the original board. Somewhere, I also have one or two other Classic boards pulled from machines which have died in some way or another over the years.

I want to keep this Classic going for a long time; hopefully it will outlive me, so I want to make sure everything is done correctly. I also figure this will help the board in general (since we have no resources on Classic I recaps).

I'd like to get this board refurb taken care of in the next month since I'm not sure how much longer the substitute board will be able to work correctly.

 

[zuiko21]

Hi!

From the picture, I can see the capacitors you mention -- they're all of the failure-prone type, like many other all-in-one Macs (e.g. SE/30). Also, since you can see some gunk around C8, I think it's time to recap!

Following my experience with the SE/30, I'd recommend this procedure:

1) get a suitable tantalum capacitor set -- our trag is a very good source.

2) desolder ALL electrolythic caps on the motherboard

3) wash the board, and let it dry for a week!

4) solder the new tantalum caps

5) enjoy your Classic! ;-)

Detailed instructions for the SE/30 recapping may apply equally to your Classic... Good Luck!

 

[Scott Baret]

Sounds good. Are there any caps I missed?

If not, I'm going to go ahead and order the cap set in the next few days.

 

[phreakout]

Scott,

It's hard to say, regarding the "dark gunk" around C8 and J8 due to the picture quality. Does it appear to be on top of the surface of the board or is it embedded deeper near or on the trace? If the latter, it could be sign of corrosion and will need to be handled very carefully; we don't know how brittle the trace is in those spots. If it is the other, then it could simply be debris or surface corrosion and is mush safer to remove. But still, treat it as if it were a case of severe corrosion.

Looks like you've found all the caps you'll need. There's no axial-lead electrolytic caps for this board, so no need to buy those. C1 through C9 are all you have to replace. Talk to trag and he will sell you the caps you need. You can wash the board, but I personally consider that an option. I've been able to resurrect boards without the need of putting them in a dishwasher.

73s de Phreakout. :rambo:

 

[bigmessowires]

Did you end up recapping your Classic? I picked up a Classic for free recently that I think needs recapping too. No sound, and sometimes boots up to a funny checkerboard pattern on the screen.

 

[Trash80toHP_Mini]

Is dishwasher/detergent the best way to clean boards after desoldering components? :?:

I used some desoldering braid along with a desoldering iron on a PDS Card. There seems to be some resin type residue on the board, (probably from the braid?) does this need to be removed with an agent somewhat more aggressive than just detergent and water?

I know I've got a memory expansion board and possibly the MoBo from a Classic I found curbside in the Big Bad Apple 8-10 years ago. It had a bad analog board (at the very least) so it went into the Hacks Que. The case is the basis for one of my more complicated hacks after having been modified to take a 10" Color CRT that was never completed . . .

. . . I seem to have lost just the CRT! :

I'll post this stuff in the Trading Post eventually, unless either of you guys have need of the Memory Expansion Card.

 

[techknight]

that resin is flux, and you need a can of flux remover works wonders. alcohol will do it too, but it takes more scrubbing.

 

[Trash80toHP_Mini]

Cool! [] ]'> I started a thread on board modding S.O.P. If you have any more info about on the subject, please post it there!