575 (+IIe card) Mystery Stain, Recap Strategy and Tools

[dzog]

Hey there! Please bear with me on this long topic. I acquired a 575 recently (a long sought-after machine for me), with a IIe card (my first real foray into Apple II), and it's becoming my big "learn to recap" impetus. So I am simultaneously assessing the board and thinking about how best to properly restore it and keep it happy for years to come.  

Though I haven't tested everything, the machine boots up fine, sound works, everything seems fine from the "boot it up and play a game" test. The display does have a relatively slight but noticeable pinkish tint which seems to either subdue over time or my eyes just adjust to.  

After heating up the rear panel cover tabs gently with a heat gun to prevent snapping, I removed the logic board. (I snapped my childhood 550's tabs clear off years ago, so I was hyper-aware of the danger here...)

Looks pretty good at first glance. No obviously leaking capacitors or corrosion; the square battery was intact before I removed it. 



A bit of probably-harmless-seeming white gunk near the CPU and ROM slots:





Flipped the board and - uh oh! What's all this?





Hmm. No nearby components look fried, and it doesn't seem corrosive -- what is this, a big spooge of flux leftover from mfg? Any ideas? I started cleaning it up with 99% iso; it's a bit stubborn in that it thinned out and spread around a bunch. 

As for the IIe card's two caps - 

This one seems ok:



But this one looks pretty bad, right? Corroded contacts, especially the negative terminal area. 



Probably not safe to use until replacing? 

(A bummer, since I have only the tiniest bit of Apple II experience and was looking forward to diving in. It will probably take me a month or two before I feel comfortable recapping a valuable thing - not to mention sourcing tools and caps.)

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OK! Now for the recap strategy. 

I've been soldering cable repairs and through holes since I was a kid, but I'm not expertly skilled and have never touched SMDs. 

My basic learning plan is:

- Play with surface mount soldering/desoldering on some junk boards. I've been collecting a few random boards with SMDs (e.g. from a cable modem, HDD controller) for this. Nothing yet with caps that look just like the Mac ones. 

- Attempt a full recap on a less-important-to-me Mac board, or two. I have a couple of LC III boards, and would probably start with one of those. 

- Apple IIe card recap

- Recap 575 and other valuable boards

Equipment:

I don't mind investing a bit of cash in tools to make the job easier and the results nicer. I have a bunch of Mac boards that need recapping at this point. If I get the hang of this, I will probably want to do it a lot. Thousands of $$ for single tools is out of the question for me but I'm happy to spend some $500 or $600 (and maybe more down the road) if it brings real benefit. 

- I bought a small bent tip for my ol' reliable Hakko FX-888. But maybe I should upgrade to an FX-951? Anyone use a 951 for Mac work? Any recommended tips? 

- Hot air rework. Is it really the best? Last I did a deep dive search on this, I came to the conclusion that "press down and slowly twist" was a better cap-removal method on these boards than hot air or dual irons, with the latter two being more tricky and error-prone (melting things). That said, this one I've seen recommended and is supposed to be nice for the price. 

- Microscope. I should probably wait on this one - my close-up vision is pretty OK, and this would probably blow out my budget. Maybe an acquisition down the road or if I sell some stuff to offset. Either way, any recs for a price/performance microscope for this type of work? 

- Caps. Electrolytic vs tantalum seems to be a great debate? My instinct is to go electrolytic, as high-quality (and preferably over-rated for volts) as I can. The circuit is designed for these caps, no? I kind of want to 'wait and see' what happens in the long run with tantalum-recapped boards before going the same route, as the rumors of failing closed/shorted (or with an explosion) give me pause. But maybe I'm just being paranoid. Can anyone recommend some high-quality electrolytics and the best place to buy? 

Thanks for reading my long and winding thread. I'm looking forward to any thoughts and advice you all might have!

 

[Realitystorm]

For when you get it working http://www.savagetaylor.com/2019/12/04/setting-up-an-apple-iie-emulator-card-in-your-68k-macintosh/

 

[AwkwardPotato]

Flipped the board and - uh oh! What's all this?

There was similar stuff on the underside of the board in my LC II when I got it. No idea what it is, perhaps something leftover from manufacturing, but thankfully it seems to be harmless. 

But this one looks pretty bad, right? Corroded contacts, especially the negative terminal area. 

[SIZE=1.4rem]...[/SIZE]

[SIZE=1.4rem]It will probably take me a month or two before I feel comfortable recapping a valuable thing - not to mention sourcing tools and caps.[/SIZE]

In the meantime, it would still be a good idea to get rid of the caps and clean up the board to stop the corrosion.

But maybe I should upgrade to an FX-951?

I have heard lots of great things about the FX-951, but I don't think it would be much more useful for 68k recapping compared to the FX-888D. The main improvement the 951 has over the 888 is that the heating element is part of the tip, which gives you better thermal recovery (and lets it heat up faster). That would come in really handy for working on modern 6+ layer boards with huge ground planes, etc. but probably wouldn't make much of a difference on boards as old as these.

Any recommended tips?

The bent tip you already bought is great, other recommendations would be small-medium size bevel and chisel tips.

Hot air rework. Is it really the best?

Hot air is unnecessary for just removing/replacing electrolytic caps. Bear in mind that excessive heat can lift pads very easily. Pressing down and twisting has been proven to be very reliable (at least in my experience), just go slowly and you'll probably be fine. If you experience IC failure later though, hot air rework would be needed.

Can anyone recommend some high-quality electrolytics and the best place to buy?

Nichicon brand caps, can be purchased on https://www.mouser.com/ or https://www.digikey.com/.

I wish you the best of luck in getting the 575 and IIe card recapped and working again 

 

[Byrd]

I believe that white residue is harmless (possibly a defect in the resin used to coat the underside of PCBs) and not suggestive of cap leakage.  I've come across it often from early to newish Mac models.

 

[dzog]

<helpful stuff>

I wish you the best of luck in getting the 575 and IIe card recapped and working again 

Extremely helpful, thank you! I have some more confidence now - maybe I'll be able to figure this out sooner (and cheaper) than I thought

The two caps on the IIe board came off with surprising ease via "press down and carefully twist." Tested them on a multimeter: C1 tested good (~26uF), C2 predictably was gonzo (open).

Yuck:



Cleaned up:

For when you get it working http://www.savagetaylor.com/2019/12/04/setting-up-an-apple-iie-emulator-card-in-your-68k-macintosh/

Awesome resource - thank you. 

I believe that white residue is harmless (possibly a defect in the resin used to coat the underside of PCBs) and not suggestive of cap leakage.  I've come across it often from early to newish Mac models.

Good to know.

 

[dzog]

Nichicon brand caps, can be purchased on https://www.mouser.com/ or https://www.digikey.com/.

OK, I've gone down the rabbit hole of Nichicon's extensive cap catalog

I think I've narrowed it down to either the UCB line ("Long Life Assurance") or UCW ("Low Impedance, Long Life Assurance"). These have 7000 hours @ 105°C ratings vs the normal 1000 or 2000. 

Is there any reason not to get the low impedance versions over the regular long-life? Unexpectedly to me, the low-impedance versions appear to be slightly cheaper. But I'd expect these to be universally "better". 

22uf

Long-Life

Long-Life+Low-Imp

47uf

Long-Life

Long-Life + Low-Imp

Also, I measured the 22uf ones I removed on the Apple IIe card to have a 6.60mm square base. I can generally find these, but some are 5.30mm square - will these still work OK? It seems like they might as the board pads/contacts are relatively "long". 

Any advice appreciated! 

 

[dzog]

Got some caps in! Diving in this weekend. Ended up with both the UCB and UCW caps and will see what fits better. Going to practice on some junk (non-Mac) boards that have a few SMT caps and then swap some number on a working LC III board (testing after each swap) before attempting the IIe card ones. 

Newbie question: is this green gunk on the LS125A pins corrosion or just leftover from mfg? I gave it a solid toothbrush and iso scrub but it won't budge. It doesn't look like it's on the entire contacts, just the upper part touching the chip, but it was also right next to the (leaked) C2. Should I keep scrubbing at this or leave it alone?

 

[AwkwardPotato]

Is there any reason not to get the low impedance versions over the regular long-life?

As far as logic boards are concerned I'm pretty sure it doesn't matter. I've used both types on boards of mine and have never had problems.

is this green gunk on the LS125A pins corrosion or just leftover from mfg?

Looks like corrosion, vinegar may help. Best not to leave it on there.

 

[dzog]

Thanks for the tips! I scrubbed with white vinegar and it cleaned up nicely. 

I completed the IIe card recap earlier today, following a bit of practice on an old Cable Modem board. I felt pretty ok with how it came out for a first timer. 

Here was my basic method: Removed the old leads with flux and heat and cleaned up the solder with braid. Put flux paste down and carefully aligned the cap. The flux paste helped keep it in place. Applied heat and just a bit of 0.015" solder (Kester 44) to one side, then the other. Tested for strength and tested connectivity with a multimeter. (C2 made that easy with the little holes.)

New C2:



Board with two new long life caps:



Put the card into the 575 (due for recap but no sign of corrosion or cap failure yet).

No fires, and the IIe card boots up with no error messages! Much rejoicing. I was able to play games off of a ProDOS 3.5" disk no problem. 



I am cautiously ready to declare the recap a success! However, there is still an issue...

 

[dzog]

OK, here's the rub: 

It won't boot from a 5.25" drive. 

Every time I try, the drive lights up and makes the initial "seeking" sound, then the card gives up and says "unable to boot from startup slot". The card is clearly communicating with the drives, but seemingly won't actually read from them. 

I have tried:

- Three different 5.25 drives. All purported to be working (one came w/ the machine), though I have no other compatible machines to test them with as this is my only Apple II device. 

- Cleaning the drives with a cleaning disk

- A variety of clean, nice looking disks from a variety of sources. No other way to verify them but I would be pretty surprised if they were all 100% nonfunctional disks. 

- Reseating cables, cards, cleaning pins, etc.

I'm an Apple II dummy - this is my first experience with Apple II so I don't know the ins and outs at all. So maybe I am missing some obvious thing. The pins around the IWM look good for what it's worth. 

Video of behavior:


View attachment Video.mov





IWM: Giving it a scrub down anyway but not seeing anything concerning, at least to my eyes...