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  1. #1

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    Default Replacing Caps in vintage macs

    Hello all-
    Our Vintage Macintoshes are starting to get to an age where their capacitors are likely to leak and do other nasty things- I want to attempt to replace capacitors in an LC II- Most people seem to say to use tantalum capacitors but then I have read a lot about these exploding....... What should I do?

    How would I actually replace the caps? (I know I would need to remove the old one then soldier new ones in but I was wondering more specifically
    Plus, IIci, IIsi, LC, LCII, LC III, CC, LC475, LC630, Centris650, 6100, 8100, 5260, 7220, 7600. PB: 100, 150, 160, 165, 540, 190, 5300, 1400. Lombard, iMacG3, iBookG3, iBookG4, PBG4, eMac, iMac G4, PMG4, MiniG4, iMacG5

  2. #2

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    Tantalum capacitors explode when you solder them in the wrong way I've not had any problem with them, they are more expensive as they last longer and ensure no leaking or capacitor failure for many more years. Jaycar sell them now.

    Rough guide on replacing caps (its too early)

    1. Have on hand a pair of fine-tipped pliers/strong tweezers, good temp. controlled soldering iron, lead-based solder. Wear a mask and ideally do it outside, you don't really want to be breathing in old lead solder and leaky capacitor contents over an extended period of time.

    2. Methods differ but I've had success by initially cutting off the capacitor "can" using small tin snips, leaving remnants of the can and plastic housing - this can be removed by hand/tweezers. You'll be left with two terminals to unsolder on the board.

    3. Hold onto each terminal with tweezers and desolder the old terminal (@ 350 - 400 deg C). The older the board, the more fragile it is to remove - don't pull up on the terminal yourself, as it will break the fragile solder pads (if the terminal doesn't come away cleanly you need more heat). Even if you do lift up the pad slightly, it can be superglued back down. So far I've not killed any pads but if you do, you can probably trace the line and solder a wire. A small amount of flux can be used to clean the region on the motherboard, but is not essential. You should also wipe off all the crusty crud on the board with some metho.

    4. "Tin" the pads on the tantalum capacitors - some "helping hand" clamps will assist here.

    5. You'll find the tantalum caps are slightly wider than the old capacitors, but line them up (ensure correct polarity) and solder on - being pre-tinned they should attach quite neatly and cleanly.

    6. Triple check your work and ensure all new caps are wired up the right way.

    Good luck!

  3. #3

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    Thanks very much-
    I feel very nervous about the whole un soldering part
    I can solder and I used to do a fair bit of it- though my soldering iron is not controllable.
    Will the polarity of the caps be marked on the board itself?
    Plus, IIci, IIsi, LC, LCII, LC III, CC, LC475, LC630, Centris650, 6100, 8100, 5260, 7220, 7600. PB: 100, 150, 160, 165, 540, 190, 5300, 1400. Lombard, iMacG3, iBookG3, iBookG4, PBG4, eMac, iMac G4, PMG4, MiniG4, iMacG5

  4. #4

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    Yes, the polarity of the caps is indicated on the board itself.

    Byrd, you get all your caps from Jaycar locally or order online?

    I've got a heap of SE/30's, Classics, Classic II's, Colour Classics, one Colour Classic II and a Mac TV to do!

    You use all tantalum capacitors, yes?

  5. #5

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    Controllable soldering irons are quite cheap these days. I think it would be worth the expense to get a new soldering iron as it will be much cheaper than having to replace damaged boards if you cook something.

  6. #6

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    oldmacs: definately practice removing components on an old PC motherboard or something. Newer boards you can work with more roughly, and hone your skills on without worry. Regarding polarity, there is a thick line on one side of a tantalum capacitor which denotes +ve (you'll see the polarity is also silk-screened on most Apple motherboards). You can also use good quality normal capacitors (105 deg rated, Japanese made), but they are a bit harder to work with and stick out a fair bit.

    macman142: I've bought some tantalum caps from Jaycar before, but they are at their most expensive here. I've also got some off trag on 68KMLA forums, he was very helpful and the caps were cheap. If you have lots to buy, I'd get them through Element14.

    samwalk: temp controlled soldering irons are awesome, I've a 10 year old Dick Smith one which works a treat. And also don't use the lead-free solder, that stuff is hard to work with on vintage Macs - lead all the way Here is the cheapest temp controlled soldering iron around:

    Soldering Station with Adjustable Heat Range (AUS Warehouse)

    (a tip: leave the page open for a few minutes, and it'll offer you the iron at a cheaper price!)

  7. #7

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    Completely agree with the above.

    Well worth investing in a good quality, controllable soldering iron. No point mucking around and making do with a rubbish one, especially considering the work involved to rectify damage from a dodgy repair...

    Open to recommendations of a good quality soldering iron!!!

    I've invested in some isopropyl alcohol and "circuit board cleaner" but not sure if it's a gimmick, yet to try it...

     good quality, controllable soldering iron
     nice sharp side cutters or small tin snips
     helping-hand clamp
     tweezers
     isopropyl alcohol or other electronics-safe cleaning solution
     replacement tantalum capacitors
     lead tin solder

    Anything else?

  8. #8

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    Looks good macman Locking tweezers help, head-mounted LED spotlight is great too. As mentioned do it outside or with a fan blasting fumes out the door/window, a little bit of soldering is OK but not for a couple of hours straight doing an entire board.

    Circuit board cleaner is the nuts, it actually does some good. I fixed my Dell 24" monitor's built-in card reader the other day, and two Alu Powerbooks with faulty RAM slots.

    JB

  9. #9

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    What causes the faulty RAM slot in the Al PowerBooks??? I have to very nice PowerBooks, a 15" 1.67 and a 12" 1.0 both with ONE dead RAM slot which is very common. Are you saying it can possibly be fixed as easily as circuit board cleaner??

  10. #10

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    Is it true that I NEED a heat-sink to do the soldering?
    Plus, IIci, IIsi, LC, LCII, LC III, CC, LC475, LC630, Centris650, 6100, 8100, 5260, 7220, 7600. PB: 100, 150, 160, 165, 540, 190, 5300, 1400. Lombard, iMacG3, iBookG3, iBookG4, PBG4, eMac, iMac G4, PMG4, MiniG4, iMacG5

  11. #11

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    heatsink-what do you mean?

  12. #12

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    Well my dad did a lot of soldering when he was growing up and still does ( just not electronic any more) and he said that he always had to use a heat sink that would transfer heat off the soldering iron or something?


    Anyway jaycar didn't have any so I guess they are not needed. Despite the poor customer service at jaycar I have all the caps ( except the one 100uf 6.3 volt ) to do the LC III. I tried to practice on a pc motherboard but the capictors were very different so it wasn't much use. I don't know when I am going to do the LCs yet but today I will fix the dc in connection on my pb 190cs
    Plus, IIci, IIsi, LC, LCII, LC III, CC, LC475, LC630, Centris650, 6100, 8100, 5260, 7220, 7600. PB: 100, 150, 160, 165, 540, 190, 5300, 1400. Lombard, iMacG3, iBookG3, iBookG4, PBG4, eMac, iMac G4, PMG4, MiniG4, iMacG5

  13. #13

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    Quote Originally Posted by Oldmacs View Post
    Well my dad did a lot of soldering when he was growing up and still does ( just not electronic any more) and he said that he always had to use a heat sink that would transfer heat off the soldering iron or something? )
    From memory (and my copy of Dick Smith's Fun Way Into Electronics Volume II), a soldering heatsink is a little clip with a coil that you attach to leads so you don't over-heat the board or component. As far as I can tell, you shouldn't need one as the capacitors on the LC III are all SMD - you'll just need to clip the leads and solder directly to the pads. If you wreck your LC board, they shouldn't be too hard to find, but try to not apply too much heat!

  14. #14

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    We bought a variable soldering iron to do the job so it *should* be alright
    Hopefully doing this will fix it though - I just couldn't believe it as the lc III was perfect when I received it. The LC II will be my next job- just it has a lot more capacitors.

    If I leave the LC II on for long enough it will eventually quit whistling for a second or so- it chimes and then does the chimes of death and then the whistling starts Again.
    Plus, IIci, IIsi, LC, LCII, LC III, CC, LC475, LC630, Centris650, 6100, 8100, 5260, 7220, 7600. PB: 100, 150, 160, 165, 540, 190, 5300, 1400. Lombard, iMacG3, iBookG3, iBookG4, PBG4, eMac, iMac G4, PMG4, MiniG4, iMacG5

  15. #15

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    So I have the tantalum caps- so the marking on the side ( long grey strip) is postive?
    Plus, IIci, IIsi, LC, LCII, LC III, CC, LC475, LC630, Centris650, 6100, 8100, 5260, 7220, 7600. PB: 100, 150, 160, 165, 540, 190, 5300, 1400. Lombard, iMacG3, iBookG3, iBookG4, PBG4, eMac, iMac G4, PMG4, MiniG4, iMacG5

  16. #16

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    Yes -

    KEMET SMD Tantalum Capacitors - Identification

    make sure you solder a small blob of solder on the pads ("tinning) of the tantalum capacitors, it will make them much easier to solder onto the motherboard. Triple check when everything is done that the caps are on the right way - if not boooooom

  17. #17

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    I love how good that makes me feel... NOTTT!!!!
    I have just removed the first 3 and they came off very well but dad wanted me to keep the leads as he is convinced that he needs leads to solder onto..... However only one of them had the leads still attached so when he gets back home I'll have to get him to solder straight to the board.

    By the way how do I know if I've 'lifted pads or tracks or something bad like that?
    Plus, IIci, IIsi, LC, LCII, LC III, CC, LC475, LC630, Centris650, 6100, 8100, 5260, 7220, 7600. PB: 100, 150, 160, 165, 540, 190, 5300, 1400. Lombard, iMacG3, iBookG3, iBookG4, PBG4, eMac, iMac G4, PMG4, MiniG4, iMacG5

  18. #18

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    You really need to remove the remnant capacitor parts/legs to ensure a clean connection when replacing with new parts. With a bit of heat the legs can be lifted away with tweezers/pliers leaving a small blob of solder on the board ready for re-soldering. The less old solder the better. The tantalum capacitors are wider than the pads on the motherboard - but by pre-tinning these you'll find they solder on quite nicely (usually with a small gap between the capacitor and PCB, they will "sit up" a little off the board).

    Lifted pads = exactly as it sounds, you'll see them lift up if too much heat is used or you've been rough. Usually though they are still connected to a trace on the PCB. I've only done it a couple of times and ended up using a pin dunked in superglue to secure the pads back down again.

  19. #19

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    Well we took all of the pins out and we can't get the solder to take to the pads - it just won't happen
    Plus, IIci, IIsi, LC, LCII, LC III, CC, LC475, LC630, Centris650, 6100, 8100, 5260, 7220, 7600. PB: 100, 150, 160, 165, 540, 190, 5300, 1400. Lombard, iMacG3, iBookG3, iBookG4, PBG4, eMac, iMac G4, PMG4, MiniG4, iMacG5

  20. #20

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    It worked!!!!!!! We replaced 3 of the caps near the power in and it now boots up. we are going to go through and slowly replace the rest. How would you suggest replacing the smallest ones? They are SOOO SMALL!!!!
    Plus, IIci, IIsi, LC, LCII, LC III, CC, LC475, LC630, Centris650, 6100, 8100, 5260, 7220, 7600. PB: 100, 150, 160, 165, 540, 190, 5300, 1400. Lombard, iMacG3, iBookG3, iBookG4, PBG4, eMac, iMac G4, PMG4, MiniG4, iMacG5

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