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Oldmacs
17th January 2013, 12:27 AM
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 :)

Byrd
17th January 2013, 06:01 AM
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) :p

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!

Oldmacs
17th January 2013, 07:18 AM
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?

macman142
17th January 2013, 10:59 AM
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?

samwalk
17th January 2013, 11:04 AM
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.

Byrd
17th January 2013, 11:57 AM
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) (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=19239)

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

macman142
17th January 2013, 12:01 PM
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?

Byrd
17th January 2013, 12:57 PM
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

macman142
17th January 2013, 01:09 PM
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??

Oldmacs
21st January 2013, 08:15 PM
Is it true that I NEED a heat-sink to do the soldering?

Byrd
21st January 2013, 08:28 PM
heatsink-what do you mean?

Oldmacs
22nd January 2013, 10:56 AM
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 :)

neoxide
22nd January 2013, 12:31 PM
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!

Oldmacs
22nd January 2013, 02:49 PM
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.

Oldmacs
23rd January 2013, 10:54 AM
So I have the tantalum caps- so the marking on the side ( long grey strip) is postive?

Byrd
23rd January 2013, 11:26 AM
Yes -

KEMET SMD Tantalum Capacitors - Identification (http://alasir.com/reference/kemet_tantalum_capacitors/)

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 :)

Oldmacs
23rd January 2013, 11:46 AM
I love how good that makes me feel... NOTTT!!!! :p
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?

Byrd
23rd January 2013, 01:27 PM
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.

Oldmacs
23rd January 2013, 01:43 PM
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 :(

Oldmacs
23rd January 2013, 02:40 PM
It worked!!!!!!! We replaced 3 of the caps near the power in and it now boots up. :D we are going to go through and slowly replace the rest. How would you suggest replacing the smallest ones? They are SOOO SMALL!!!!

Oldmacs
23rd January 2013, 03:35 PM
Spoke WAY too soon- Its back to taking 2 minutes to boot :/
Must be some of the other Caps now :(

Byrd
23rd January 2013, 07:14 PM
Solder not taking to pads - is the iron hot enough? I've also found you need to slightly scuff the pads - with a needle or razor - to expose some of the copper traces, this will make the solder attach more effectively.

The small caps, same as the big ones, but you could use some clamping tweezers/pliers to hold the cap in place to make it easier to position.

good work though, it's great seeing a once dead Mac come to life again :)

JB

Oldmacs
23rd January 2013, 08:56 PM
We got it done eventually though we only did three of the capacitors nearest to the Power Supply.
It was so strange though. As soon as we replaced the Caps I re assembled the computer, plugged it in and it booted straight away- And it had been unplugged for a day or so. Previously it needed to be running for about 5- 10 minutes then it would chime and go, If turned off it would still boot within about 5 minutes. So for about 1 hour I tested it- it booted perfectly no matter how long it was unplugged. Then it decided that it would go back to needing 5 minutes to boot. I really hope that something hasn't gone wrong.

I know this is a long shot but If I posted an LC II board with the capacitors, would anyone be willing to do the replacements? (i'd be willing to pay a bit as well) :) Just putting it out there- Those little caps look VERY scary.....

Byrd
24th January 2013, 09:50 AM
The improved caps probably helped improve the reliability of the board, but as you are aware the other suspect caps aren't helping things. I'd be willing to help but not sure if I've the time to do a cap repair at the moment - moreso if I find an LC board I'll send it your way :)

68060
24th January 2013, 10:24 AM
There was a guy on the vintage macs mailing list who was selling cap kits. its a list off the LEM site.

Oldmacs
24th January 2013, 10:47 AM
The improved caps probably helped improve the reliability of the board, but as you are aware the other suspect caps aren't helping things. I'd be willing to help but not sure if I've the time to do a cap repair at the moment - moreso if I find an LC board I'll send it your way :)

That would be great :)
Dad and I were all right with the bigger caps, but the smaller caps are going to be scary :P
If you find a board, I guess the Current LC III board could become a practice board- If we manage to replace all the caps successfully, its a bonus having two board :)

Next thing will be the LC II- Which seems VERY scary because of how close all those small caps are :)

Oldmacs
24th January 2013, 10:48 AM
There was a guy on the vintage macs mailing list who was selling cap kits. its a list off the LEM site.

Well the thing is that I bought all the caps bar one- that one I will get off ebay- Its just I don't want to ruin the board and therfore have a completely non working LC III and LC II :P

neoxide
25th January 2013, 08:42 AM
Well the thing is that I bought all the caps bar one- that one I will get off ebay- Its just I don't want to ruin the board and therfore have a completely non working LC III and LC II :P

If you want, I can try doing the caps for you... I've been meaning to start changing the caps over on some of my macs. Only issue is that it might take a little while (you know what my turnaround is like!) The worst that can happen is that I'll wreck the board. I have a few more where that came from, so I'd replace it if anything like that happened. I've got some reasonable connections with some local electronic component distributers (much cheaper than JayCar), so I could probably find that missing cap for you. Up to you - just warning that I have no idea how long it'll take, plus I'm driving up your postage budget!

macman142
25th January 2013, 12:49 PM
We should have a "MacTalk International Vintage Mac Capacitor Replacement" meet.

Where we all bring our piles of LB's, BULK caps, soldering irons and make a weekend of it. Would almost be worth the combined effort. Might be a world record for most vintage computers repaired in one sitting hahaha.

Oldmacs
25th January 2013, 01:59 PM
Yes!!!!!!!!!
However I'm in Sydney :p

Neoxide- I will see how I go and yes- I've got to be careful of my postage quota :p if all goes badly with the rest of the lc III caps I would rather pay postage.

Byrd
25th January 2013, 07:40 PM
macman = WA
Oldmacs = NSW
me = VIC

as much as I'd love a vintage Mac meet, it doesn't seem too likely at the moment :) I'm trying to avoid soldering at home too much at the moment as we have a toddler, so it's really only "my stuff" I solder, but if someone has the facilities and free lunch, then you're talking ...

Oldmacs
25th January 2013, 09:33 PM
Well Sydney is always nice in April :p

When I Finnish school I'd be free(ish) to attend some sort of vintage mac meet :) but the distance makes it VERY hard........

macman142
29th January 2013, 06:00 PM
Hey I can manage NSW or Vic, so long as it co-incides with one of my work trips.

Oldmacs
29th January 2013, 06:35 PM
I can manage NSW only :/ Just that being 16 makes stuff hard :(