[A1200] Let's change those capacitors!

[Turran]

Amiga 1200

2 pieces 1000µF x 10V : get on ebay or something. Elfa only have 63v which are way to big.

2 pieces 470µF x 16V : https://www.elfa.se/elfa3~en_us/elfa...item=67-043-65

4 pieces 100µF x 6.3V : https://www.elfa.se/elfa3~en_us/elfa...item=67-000-41

2 peices 22uF x 35V Bipolar: https://www.elfa.se/elfa3~en_us/elfa...item=67-120-12 - for C324 and C334

3 pieces 22µF x 35V : https://www.elfa.se/elfa3~en_us/elfa...item=67-041-42

3 pieces 10µF x 35V : https://www.elfa.se/elfa3~en_us/elfa...item=67-042-14

2 pieces 47µF x 16V : https://www.elfa.se/elfa3~en_us/elfa...item=67-010-56

[Turran]

This is strange.. On the first motherboard I did (1D4), it had 22uf, 35V everywhere there was a 22uF. On this 1A board, it has 22uF, 25v everywhere..

Guess I'll go for 35v anyway on this one.

[kipper2k]

Originally Posted by Turran

This is strange.. On the first motherboard I did (1D4), it had 22uf, 35V everywhere there was a 22uF. On this 1A board, it has 22uF, 25v everywhere..

Guess I'll go for 35v anyway on this one.

As long as the voltage rating of the capacitor exceeds the actual voltage it will be subject to it is fine

[kipper2k]

Originally Posted by ubermick

Cheers for the heads up, Retrofan. Was hoping to avoid sending it to them, since I know it has to go from San Francisco to Cardiff and back again, meaning I'll be without Amiga for 3+ weeks while it's doing it's thing. (Plus it's $75 when you include the return shipping, I could almost replace the board for that!)

But if it's the only (and best) option, then...

If you want to send it to me (Canada) instead, i can do it for you

[Turran]

Well, went a lot better this time then last. Much easier with a hot air gun. Three things I learned this time.
1: Only gently push the caps when removing with hot air gun. Put no pressure at all on them basically (for the surface mounted ones atleast). Next time I'll just try increasing the air flow and they should fly away by themselves when they had enough foreplay.

2: If the surface mounted ones starts to bulge upwards when heating, stand clear cause its gonna POOOOF. Too much heat on the cap, not enough on the bottom part where the solder is.

3: If, while removing a cap, it lands in your lap, it hurts. Man that's hot.

Caps removed. No accidents this time.



New caps on



Bipolar ones for the sound. They're quite large so not much to solder on without melting the plastic around those areas...


Also replaced 6 caps on this memory/FPU card..


Two more amigas to practice on before I'll do anyone elses. God knows I got tons of caps bought.

[kipper2k]

looking at your pictures, Are you using through hole capacitors to replace the surface mount caps on the A1200 ?. It looks like you are, you have to be careful doing that as it is easy to rip a pad off the motherboard. Doesn't affect the operation but you should always replace with same type technologies

[Turran]

Originally Posted by kipper2k

looking at your pictures, Are you using through hole capacitors to replace the surface mount caps on the A1200 ?.

I do yes. I bend the legs outwards about 3 mm from the caps and cut them off to size so that it takes up the whole surface area before soldering them on. That way I only need the hot air gun for removal, not assembly.

[prowler]

Originally Posted by Turran

I do yes. I bend the legs outwards about 3 mm from the caps and cut them off to size so that it takes up the whole surface area before soldering them on. That way I only need the hot air gun for removal, not assembly.

That's a good technique to use when there's sufficient headroom , and they look good when mounted too.

[Retrofan]

I've got a heat air gun like this: http://www.tooltime.co.za/ProductDetails.aspx?id=2933 , with the proper Air nozzles. Can I use it? What temperature should I use?

[magge]

That looks great Turran! nice job

[Turran]

Thanks. I'm still a noob so I'll take any advice you have though. I bought surface mounted caps first but when I looked at them, I realized I'm going to ruin a lot of amigas trying to fit those for my first attempts. Any advice how to get them on appriciated, considering I blew up two of them just trying to get them off.

@Retrofan: I use 320c and 6/10 on the fan speed. I also got some heat resistant tape with the heat gut that I carefully cut pieces of to protect the parts around the cap I'm removing. It really helps cause otherwise I'd have melted some plastic parts off =)
I watched youtube quite a lot before though, to see how to move the heat around the cap and not hold the hot air-stream on any one location.. still takes practice =) No idea how it would work with that big machine though.. need a very tiny nozzle for it.

Bending the caps is also good for protecting the caps. I hold the leg I'm currently soldering on with a small plier, distributing the heat that would otherwise go up into the cap. Another youtube tip =)

@magge: Thanks =) I got two more of my own to practice on before I can help you removing your caps =)

[keitha1200]

LOL I've got a heat gun like the above, but I used it for stripping off classical car under-seal Think I would need a lot more convincing before putting it anywhere near my Amiga Nice job never the less

Question? what's the difference with the large caps and the original styled small ones? Is it purely cosmetic? I'm thinking the larger caps might be less 'fiddly'.

I'm pretty much a newbie at this soldering lark but so far, I've found the solder braiding stuff pretty good, where as the pump wasn't so good; when I was removing batteries from memory expansion/500+

[Retrofan]

Originally Posted by keitha1200

LOL I've got a heat gun like the above, but I used it for stripping off classical car under-seal Think I would need a lot more convincing before putting it anywhere near my Amiga

Really I think the same. Surely someone will tell you can't use it, but I don't know the reason and I'm not sure. I think I will use chipquik like always.

[keitha1200]

I've also got one of them soldering guns (heats up in seconds) but I'm thinking about: attaching a sawing needle to it (attaching it with steel wire) thus allowing me a finer point for heating up the solder. Pure theory at the moment

[Turran]

Originally Posted by keitha1200

Question? what's the difference with the large caps and the original styled small ones? Is it purely cosmetic? I'm thinking the larger caps might be less 'fiddly'.

Function is the same I think. Just that the "large" caps I used (through hole capacitors) are meant to go through a hole in the motherboard and soldered on the other side. The ones that are there to start with are surface mounted with no holes.

Originally Posted by keitha1200

I've also got one of them soldering guns (heats up in seconds) but I'm thinking about: attaching a sawing needle to it (attaching it with steel wire) thus allowing me a finer point for heating up the solder. Pure theory at the moment

Hehe, then you might as well get a normal soldering iron for $15

[keitha1200]

Originally Posted by Turran

Hehe, then you might as well get a normal soldering iron for $15

I've already got 30w iron and it's: 'Big girls pants!!' anyhow DIY is far more fun

Still can't find supplier/someone who sells all the same components, who's reasonable priced

Think I'll get both types and see what works the best for me and my limited skills

[Turran]

Here is another tip, solder the legs on in this order. I did it the other way around (though hole caps first) and they just ended up being in the way for the surface mounted ones. Through hole are the easiest, so just leave them for last.

Surface mounted in red. Two numbers each, ranged for hardest to reach. You might think you should do 2 first, then 1, but if you do 1 first, the cap will be locked in place while you maneuver the solder iron in for 2 without touching the IDE port, the RF modulator, the motherboard or the cap itself.

[Turran]

Just noticed. If you do use through hole caps like I did above, the top metal shield will no longer fit. The caps will press against them since they are slightly higher.

[keitha1200]

Thanks Turran

'A picture speaks a thousand words'

Just got to sort-out a source, then plan a spare couple of hours to get on with it

[Turran]

Personally, I love when (other) people show pictures of their work. Thats why I'm gonna keep doing it. It is NOT to brag or anything since for anyone serious about this, it probably looks like crap.

Anyway, did an A600 today.

Things learned:
1: There is almost no room for the bipolar caps between the sound outlets and keyboard connector. Had to angle them to get in there with the soldering iron.

2: The caps on the far right (not in pictures) can not stand upright or the floppy wont come all the way down. Had to resolder them horizontally as well.

3: Take pictures before you start. One cap had the wrong markings on the mainboard. Looking at the "frame", the little plus sign was on the side that should have been negative according to the frame. Had to look at pictures.

4: I've had a hell of a time cleaning out the holes for the through hole caps. I can never quite get them clean enough so that I can stick a new cap in, either with solderwick or a solderpump. I found that holding a metal sewing needle with a plier and slighly pushing it into the hole, while melting the solder from the other side with the solder iron, the sewing needle would get pushed through a bit. I could then remove the solder iron and soon afterwards just pull the needle back out, leaving a perfect little hole since the solder does not adhere to it. Just dont use a too big of a needle so you damage the track.