Classic II restoration

[4seasonphoto]

Unrestored Classic II motherboard with leaky capacitors:

Getting ready to solder new capacitors (applying solder paste with a syringe). I made a mess of the foil trace for the + side of C3, and you might just barely be able to see that I've already mended it by soldering a tiny bit of wire in order to reconnect the new copper foil pad to three existing traces. The adhesive copper foil is sold as Datak Circuit Fix.

Done! Some of the new capacitors are sitting a bit skewed. Note that the original aluminum cans have a black stripe marking the - terminal, but with the new chip capacitors, it's reversed, and the stripe indicates the + terminal!

It works!!

I've got one more C2 motherboard to rework, and I think for that job, I will try the Chipquik SMD Removal Kit:

http://chipquik.com/newsletters/cq_new_june_2004.htm

 

[Osgeld]

hot air, quickchip and solder paste is all abit overkill for some capacitors, I replace them all the time with a standard iron and a gentle hand, but whatever floats your boat, least theres some more vintage mac's out there

 

[Mars478]

Makes me sad to look at my Classic 2.

 

[phreakout]

Very nice job, 4season! Be proud of the success you have accomplished. Just keep practicing with those type of skills and they will get you someplace in life. I guess that Classic 2 is set for another 20 years of service, eh?

73s de Phreakout.

 

[4seasonphoto]

Very nice job, 4season! Be proud of the success you have accomplished. Just keep practicing with those type of skills and they will get you someplace in life. I guess that Classic 2 is set for another 20 years of service, eh?)

Thanks! If I knew how to do a flawless job using just my regular soldering iron, I'd be all over it, but as it was, I thought I was lifting up too many of those foil traces, and wanted to do better than that. I've also been encountering more SMDs in the audio stuff I like to tinker with, and thought it was time I learned how to deal with that. I love how the Classic feels almost like a new computer now. In a way, i guess it is.

 

[tomlee59]

Congrats on a job well done! Nice to see another Compact Mac kept out of the landfill.

 

[madcow]

Just curious, how did you remove the old capacitors? I have just order a set of new capacitors for my Mac SE/30 but I am not confidence in doing the replacement by myself. I worry that I could mess things up.

 

[tomlee59]

As in trying to acquire any other skill, practice makes perfect. Grab a junk circuit board, and practice removing its caps. You'll quickly learn how much heat is too much, how long is too long, how not to pull on the cap other than very gently, etc. Once you've mastered the technique, go to work on your real board.

 

[4seasonphoto]

Just curious, how did you remove the old capacitors?

Not very well!! I wound up lifting the copper foil in a few places. It still works okay, but I'm going to try the Chipquik SMD removal kit on the next C2 motherboard and see if that makes things easier. The solder contained in that kit is a special alloy which remains molten at much lower temperatures, so it should be possible to simply wet the capacitor terminals with the stuff, then slide the old capacitor right off. Regular solder solidifies much too quickly.

 

[Osgeld]

another trick is to tack solder a thin piece of wire tween the two sides and then heat up the wire melting both sides @ once

I have not tried it yet, and in theory it seems like it would not be well suited to smd electrolytic (can type) caps

then theres the ole cut the can off, which frankly scares me since you need to put immense pressure on the thing your trying to gently remove

I am planning out an article on methods, when I get it posted ill be sure to let everyone know

 

[Unknown_K]

Just curious, how did you remove the old capacitors? I have just order a set of new capacitors for my Mac SE/30 but I am not confidence in doing the replacement by myself. I worry that I could mess things up.

Just cut the capacitor off at the base above the black plastic. Then you just remove the black plastic base exposing the leads and just desolder them one at a time.

 

[trag]

That's a nice looking job 4seasonphoto. Thank you for posting it.

The ChipQuik is a bit of overkill for capacitors, but it will make them easier to remove using just one soldering pencil. However, using two pencils is faster, about as easy and requires less cleanup.

Solder mixed with the Chipquik alloy is a little difficult to clean up. Make sure you have a supply of solder flux on hand. Using plenty of flux is key to getting that stuff off of your circuit board.

Keep in mind that if you use much of it, you can kind of roll it (some of it anyway) over onto the solder mask and collect it after it hardens. Then you can reuse it, if you don't mind keeping little bits of moderately toxic metal around.

The place where I find ChipQuik useful is in desoldering surface mount chips. When you mix it into the existing solder, it does lower the melting point. This makes it possible to either remove the chip with less time under the hot air, or, if you form a bead of ChipQuik across all the pins, you can often take a medium sized SM chip off with just a 45 watt soldering pencil applied to the bead and moved around a bit. Smaller SM chips (8 - 16 pin SOIC, e.g.) only require a 15 watt soldering pencil with ChipQuik.

 

[4seasonphoto]

The ChipQuik is a bit of overkill for capacitors, but it will make them easier to remove using just one soldering pencil. However, using two pencils is faster, about as easy and requires less cleanup.

I hate to think that I GAVE AWAY the ideal 2nd iron for the task: A Weller micro soldering station. But I was moving and giving things away left and right, and I hadn't even used that thing in the 10+ years I had gotten it. And of course 18 months later, I've got a bunch of SMD projects. :-/

Tried the ChipQuik on a 2nd Classic II motherboard and it worked like a dream: No lifted foil at all, save for the one cap I tried to remove without it. (but in the end, the board seemed deader than a doornail--maybe I should have paid attention to the signs of water damage) Besides the old computers, I also have a DAC chip to replace on one of my amplifiers. Unlike the solder paste, ChipQuik doesn't seem to have an expiration date, and I figure this $21 kit may last me for a few years.

Wonder if ChipQuik is Field's Metal (bismuth, indium, tin alloy).

 

[protocol7]

I just got a Classic II and it seems I might need to replace the caps too. I haven't the tools to open it yet so I don't know what's inside. What capacitors (type and quantity) would I need to order from trag to re-do the whole board?

 

[4seasonphoto]

I just got a Classic II and it seems I might need to replace the caps too. I haven't the tools to open it yet so I don't know what's inside. What capacitors (type and quantity) would I need to order from trag to re-do the whole board?

'Fraid you have to count them yourself, because my two Classic II motherboards were significantly different from one another, and IIRC, the number of capacitors was a little bit different too. But both used 1, 10 and 47 uf. Think one used (3) 47s, (13) 10 uf and (2) 1 uf, and the other used a couple more of the same values. Never hurts to order spares, as they are inexpensive and easily lost.

 

[Mars478]

I just got a Classic II and it seems I might need to replace the caps too. I haven't the tools to open it yet so I don't know what's inside. What capacitors (type and quantity) would I need to order from trag to re-do the whole board?

Ask trag on the forums. He sell TONS of caps (and ones that don't leak for that matter.) for cheap.

 

[protocol7]

Never hurts to order spares, as they are inexpensive and easily lost.

Good point. I'll hold off until I know what's inside but I'll probably order some extra ones anyway.