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Replacing se/30 capacitors question
Posted by: Ultimategamer87 on 2016-10-13 08:11:12 Hello i have a macintosh se/30 board that has very low sound, and i need to replace the capacitors. Can i replace all the surface mount capacitors with just normal electrolytic capacitors? -thanks
Posted by: joethezombie on 2016-10-13 09:09:34 Yes you can, but you'd be better off using tantalums. Also, replace that battery or remove it completely before it leaks.
Posted by: Ultimategamer87 on 2016-10-13 09:41:32 Yes you can, but you'd be better off using tantalums. Also, replace that battery or remove it completely before it leaks. Why would i be better off using tantalums? Just wondering.
Posted by: flashedbios2012 on 2016-10-13 09:51:18 Are the surface mount caps the silver and black ones? How do you desolder those?
Posted by: Ultimategamer87 on 2016-10-13 09:55:07 Are the surface mount caps the silver and black ones? How do you desolder those? I have never done this before, but i have heard of people using hot air to desolder them.
Posted by: flashedbios2012 on 2016-10-13 10:00:08 so a hair dryer? Or do I have to go purchase a hot air gun? I may just pay a local electronics repair shop to do it
Posted by: Ultimategamer87 on 2016-10-13 10:05:57 so a hair dryer? Or do I have to go purchase a hot air gun? I may just pay a local electronics repair shop to do it You have to buy a special tool that blows really hot air (over 400 degrees f) to desolder them. Im actually just going to send my board to maccaps.com and have him recap it.
Posted by: Juror22 on 2016-10-13 10:41:46 Sounds like you have a decent plan, he does good work. You don't want to learn about recapping on a board like this, maybe practice on some scrap electronic boards first and get good at it, before you work on some of you your vintage bounty.
Posted by: joethezombie on 2016-10-13 10:44:41 Yes, under those capacitors are very fine circuit traces on the motherboard and if you overheat them or scrape them you'll cause a lot of damage. You can also lift the pads if you don't do it right. Also keep in mind if the electrolytic fluid has escaped from the existing capacitors, that stuff is like acid and eats away at those traces so just replacing the capacitors may not be enough. Edited to add, the reason why tantalums are better is because they will not leak in the future so one fixed now will last forever. If you use the electrolytics, just remember to do it again in 10 or so years or when the fluid leaks out again it will dissolve the traces.
Posted by: flashedbios2012 on 2016-10-13 11:01:29 they should have used tantalums to begin with
Posted by: joethezombie on 2016-10-13 11:10:34 Yeah, they should have! Funny thing is, some boards like the Quadra 700 is all tantalum, and the IIfx board has pads for tantalums, but then they used those crappy aluminum cans! Video cards aer even stranger, some of them have tantalums and some of them have aluminum cans. It seemed that Apple just used what they could get the cheapest at the time of production.
Posted by: Ultimategamer87 on 2016-10-13 12:00:49 Yes, under those capacitors are very fine circuit traces on the motherboard and if you overheat them or scrape them you'll cause a lot of damage. You can also lift the pads if you don't do it right. Also keep in mind if the electrolytic fluid has escaped from the existing capacitors, that stuff is like acid and eats away at those traces so just replacing the capacitors may not be enough. Edited to add, the reason why tantalums are better is because they will not leak in the future so one fixed now will last forever. If you use the electrolytics, just remember to do it again in 10 or so years or when the fluid leaks out again it will dissolve the traces. Do you know about how much it will cost me to send my se/30 board to maccaps.com? I have 2 regular macintosh se computers that have never had to be recapped so im just wondering.
Posted by: joethezombie on 2016-10-13 12:25:20 No idea. I've never used his services as I do all my own work. I would guess the SE/30 is one of the more complicated boards with a high capacitor count, so probably at the higher end of his scale. Go to his website and email him directly. There's also a few here that are starting to offer this service, maybe at a cost savings.
Posted by: Ultimategamer87 on 2016-10-13 12:27:04 No idea. I've never used his services as I do all my own work. I would guess the SE/30 is one of the more complicated boards with a high capacitor count, so probably at the higher end of his scale. Go to his website and email him directly. There's also a few here that are starting to offer this service, maybe at a cost savings. Could you possibly refer me to a person on this forum who does se/30 recaps?
Posted by: TimHD on 2016-10-13 12:30:02 Could you possibly refer me to a person on this forum who does se/30 recaps? See. https://68kmla.org/forums/index.php?/topic/28590-if-you-are-desperate-for-recap/
Posted by: fimbulvetr on 2016-10-13 13:40:43 There are maccaps listings for recapping on eBay, which should give you an idea on what her charges.
Posted by: Unknown_K on 2016-10-13 14:53:36 I tend to replace capacitors with the same type as used by the manufacturer if still available. Hobby machines don't get used the same as they were when new so even aluminum analytics should last a very long time. Tantalum capacitors short closed (they explode), depending on the circuit that could be very bad. Also tants are not the best for audio circuits.
Posted by: tact on 2016-10-13 21:16:11 SMD work is a little trickier than using a standard leaded radial cap. May also be worth getting a tool like this for smd work. Less of a chance of pulling off one of the pads while removing the old caps >< https://www.circuitspecialists.com/Tweezer-Style-Soldering-Iron-For-SMD.html
Posted by: trag on 2016-10-13 23:59:15 Honestly, it's just not that hard. The biggest requirement is patience followed by care with a dose of gentleness. Get two 40ish watt pencils at Radio Shack (I used to use the grounded 15W pencils but they're too weak), let them heat properly, apply liquid flux to the old solder, and then with one pencil in each hand apply a pencil to each side of the cap. Don't drill or grind. Just wait. If the joint doesn't seem to be heating, retip your pencil with solder and reapply flux to the joint. Heat conduction is key. Ideally the cap will be loose is about 5 seconds but sometimes it takes longer. Then you just lift it with the pencils and wipe it off on a damp sponge. All the warnings about lifted pads and traces underneath are why you don't drill or grind the pencils into the board. Just gently apply heat until the cap comes loose.
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