Classic II Corrosion: Am I Screwed?

[Crickett]

BACKGROUND:

So I picked myself up a decent-condition, "not working" Classic II on eBay a month ago. The listing showed it powered on with the checkerboard screen, so I figured "hey, easy fix". When I got it, the screen wouldn't light at all, no chime, just the sound of the fan running. I pulled the logic board out & wasn't surprised to find an oily-looking substance on the board around the capacitors (all of them), so – having done my research – I tried cleaning it up with cotton swabs & isopropyl alcohol, along with reseating the RAM & ROM. That got it to power up to the chess board for only a few minutes before the CRT went dark. I haven't gotten it to light since. I've tried re-cleaning the board with isopropyl, re-re-seating the RAM & ROM, re-soldering the CRT yoke connecter pins & the logic board connector pins on the analog board, & even the mythic cycle in a dishwasher, all to no avail (& not making it worse, as far as I can tell). The next fix I'm considering is a full recap, but I'm concerned the board might be too far-gone.

ISSUE:

So to the point: have my board's leaky capacitors (in your opinion) corroded the pins on the CPU (among other ICs) to the point of being beyond reasonable repair? If not, I'll be enlisting the aid of the great folks here to get my board recapped! Here are pics of the area in question:

(click for bigger)

The area around capacitor C13 & the CPU





Close-ups of the CPU pins (hooray water-drop iPhone photography )

I also noticed in MidnightCommando's post about his Classic II (here), the close-ups of his board seem to show the same pale-yellow corrosion as mine, although his looks a bit more severe. Maybe there is hope for my poor little compact?

 

[techknight]

not enough to matter. ive gotten TVs running with corrosion on the main CPU thats MUCH worse than that. your problem is toasted caps. they all need replaced before further diagnosis can be done.

 

[Crickett]

not enough to matter. ive gotten TVs running with corrosion on the main CPU thats MUCH worse than that. your problem is toasted caps. they all need replaced before further diagnosis can be done.

Sa-weet! I was a bit concerned when a trip through the dishwasher didn't clean up that corrosion much at all & didn't want to get it recapped if the corrosion is a fatal problem anyway. But it sounds like I'll be enlisting the aid of trag and/or phreakout!

Anyone else have more stories of Macs pluggin' right along with corrosion like this?

 

[JDW]

I would call that "gunk" sitting to the back (under the chip) and in between those pins, rather than "corrosion." That gunk could consist of a variety of things, including leaked capacitor fluid which you were able to clean off outside the chip but not underneath. I've seen this gunk before in my own experience. What I do is take a very tiny ice-pick shaped metal tool (about the thickness and shape of a wooden toothpick) and ever-so-slightly scrape in between each pin of such IC's, far back enough under the chip to ensure that no two pins are directly connected together by the gunk. (For chips that have a very tight pin spacing, I sometimes use an XACTO knife -- but such requires even more skill that metal pick, since you don't want to cut into your board -- just scrape away the gunk!) The gunk is not likely causing an electrical short between the pins that would fry the chip, but stray capacitance is a concern especially since some of that gunk is spilled capacitor fluid. So I would advise you to carefully scrape it away between each pin.

Before you scrape though, be sure you've don't your best to clean it off with alcohol outside the chip. I use a toothbrush and electronics grade dehydrated Ethanol for that task. That combination works so well to solidify the gunk that I don't have to do much scraping at all to clean the gunk away between the chip pins.

Lastly, I've read stories from many people here who merely clean the board and expect it to work like new. Yes, that does give the appearance of "restored operation" for a time on some boards, but the fact is, leaked fluid means your caps are either dead or at a diminished capacity. In any case, they all need to be replaced. Do not expect your machine to work properly until you do that. And yes, I am fully aware it is not a fun or quick job. But it is a necessary one.

 

[J English Smith]

Just curious: What is the lifespan of a capacitor? How much do storage conditions matter in their lifespan? Just curious. My oldest machine at this point is a Classic II that appears to still be going strong...also several Powerbook 150s...

 

[Dog Cow]

Depends on the type. What we typically see failing and leaking are electrolytic capacitors.

 

[Unknown_K]

Recapping Classic II boards is a pain because of the way they are spaced close to other parts (which also means the leaking goo will get into other important areas and make a mess). Most likely a recapping will give you video again, and hopefully nothing else is wrong.

As far as capacitors that leak, it is mostly the surface mount ones that do. I have yet to have to replace any of the other analytics on motherboards.

 

[JDW]

While it does depend on the environment (especially heat) and hours in use, we are talking about vintage Macs here. Simply put, expect the fluid filled electrolytics to last 15 years before they start to noticeably degrade in your vintage computers. Solid tantalum caps or the ceramic chip capacitors used all over the logic board will last as long as the logic board (60 years?). And while it is true that the tiny SMD type electrolytics tend to leak more visibly, the fact remains that non-SMD electrolytics also leak or otherwise experience diminished capacity after more than a decade of service. That is why when I recap my SE/30 logic boards, I take the time to also replace the two large axial caps as well. Anything less than a full cap replacement is not a complete job. And an incomplete job may result in unexpected operation from time to time.

 

[phreakout]

I agree with JDW. Replacing all of the SMD caps with tantalum-type along with all axial-lead electrolytic caps will help extend the life of that logic board. Crickett, send me a PM if you'd like me to do some recap work. Get a hold of Trag, should you need to order replacement parts.

73s de Phreakout. :rambo:

 

[Paralel]

Is there anyway to replace the axial lead caps with something that can't leak?

 

[Unknown_K]

I have never seen an axial lead capacitor leak.

 

[Mac128]

Recapping Classic II boards is a pain because of the way they are spaced close to other parts ...it is mostly the surface mount ones that do.

This brings up an interesting question. By today's standards, there is really no point in owning a Classic II for any real work. It is essentially a stunted SE/30, which has neither the same power or capacity. Both it and it's sister Classic were giant steps backward.

So the question is, besides the form factor, is there any reason not to just get an SE or SE/30 and relegate the Classic series to the history books? The SE series was the last of the easy to repair compacts, and for the trouble the Classics cause, I'm thinking the last best EOL for the compacts to maintain modern functionality.

 

[JDW]

Whether the dissipated electrolyte can be seen or not (it is usually not seen), it is a fact that heat slowly degrades and dissipates the fluid over time. This occurs more rapidly on smaller sized capacitors, of course. And keep in mind that a capacitor may give a correct capacitance reading and still fail in-circuit due to its increased ESR rating. ESR speaks of the "resistance" rating of the capacitor in series while in the circuit. ESR Meters exist to test this value, even while the capacitor is in-circuit. An extremely high ESR value could cause the capacitor to rupture at some point.

Suffice it to say, whether you see the aging effects or not, you should replace all the capacitors, including the big electrolytics. It's been about 20 years on a lot of these compact Macs, folks. It's time to change those caps. (And yes, there are such caps even on the 128k logic board too!) With regard to the SE/30, the kit I purchased from Trag (at a very economical price) included both axial caps on the logic board. I did the job myself, but some on our last such as phreakout offer to do the job for a nominal fee. Unless you are skilled at the job, it would be worth it to pay to have the job done professionally. And it's not like you have to do this every few years. Once the main SMD caps are swapped out for tantalum versions, there will be a relative few fluid filled caps. And since those fluid filled caps are all the large sizes, I doubt you will need to swap them out again for at least another 15-20 years. Perhaps by then, assuming you are still around then, there will be a non fluid-filled version available to replace them.

Lastly, I agree with Mac128. I think the Classic's plastic case is a bit more spiffy than the SE and SE/30 series, but except for that, the SE/30 is better all around.

 

[Unknown_K]

I had a Classic II but got rid of it. I prefer the SE , SE FDHD, and SE/30 models I still have. For one thing you have expansion options in the SE line, 3 of 4 compacts I own have ethernet.

 

[Paralel]

Are there are caps on the analog board that one should consider replacing as well even if they aren't leaking at this point in time?

I love my Classic II for purely sentimental reasons.

 

[JDW]

Most of the analog board caps are of the larger size variety, and as a result, most of the time you can get away with good system operating without swapping them out. My SE/30 has new logic board caps but I never spent the time to replace the analog board caps. A lot of the bit analog board caps are very big and over-spec'd which is why your system still works even though the capacity has diminished through the years.

If you want to be thorough and have the best electrical functionality possible, then yes, by all means, replace all the caps on the analog board too. But once you start on a job like that, then the next logical step is to also swap out the electrolytic tanks in the PSU (power supply) too. And for an SE/30 power supply, that would be a real time consumer!

 

[techknight]

not to mention very expensive on some of those caps.

but WARNING. you cant just go out and replace your caps with just any caps, need to do some research on the known "good" capacitor companies. as alot of caps these days are chinese junk that will fail sooner and more destructively in a shorter timespan than what your leaking cap already is in its current state.

 

[Crickett]

This brings up an interesting question. By today's standards, there is really no point in owning a Classic II for any real work. It is essentially a stunted SE/30, which has neither the same power or capacity. Both it and it's sister Classic were giant steps backward.
So the question is, besides the form factor, is there any reason not to just get an SE or SE/30 and relegate the Classic series to the history books? The SE series was the last of the easy to repair compacts, and for the trouble the Classics cause, I'm thinking the last best EOL for the compacts to maintain modern functionality.

Lastly, I agree with Mac128. I think the Classic's plastic case is a bit more spiffy than the SE and SE/30 series, but except for that, the SE/30 is better all around.

Y'know, that's pretty much my exact line of thought regarding these old compacts. I was (am) looking for a decent SE/30 as my primary compact, but the Classic II was a great deal (at the time) & was always my second choice. I greatly prefer the look of the Classic/Classic II cases, but functionally they clearly don't compare to an SE or SE/30. So that begs the question: has anyone tried putting an SE or SE/30 in a Classic case?

I know the back ports don't 100% line up, an SE/30 back bucket probably wouldn't fit on a Classic front (on account of the Classic's slight curve), a Classic's analog board might not power/fit an SE/30 logic board, but I can't imagine that a moderate amount of modification wouldn't result in a decent SE/30-powered Classic. Has anyone tried/succeeded doin' this?

 

[yuhong]

It is essentially a stunted SE/30, which has neither the same power or capacity. Both it and it's sister Classic were giant steps backward.

Actually not directly. You can think of it like this:

The Classic II was based on the 68030-based LC II that was designed to fit in a Classic case.

The SE/30 was based on the 68030-based IIx (actually more like the IIcx) that was designed to fit in a SE case.

The LC II was a 68030-based upgrade to the 68020-based LC (that was actually released after the Classic II, but all LC II added besides 68030 that was not in Classic II was 4 MB soldered RAM because by then Apple finally realised 2 MB was not enough for System 7).

The IIx similarly was a 68030-based upgrade to the original 68020-based II.