Capacitor problems

[paulo_becas]

I was surfing the web when i came across this brazilian website with some interisting stuff.
Looks like the guy knows what is doing, the main problem are the leaking capacitors on the amigas that tend to get worse over time, i didn't knew that, in this tutorial he explains how to swap all the capacitores in the 600 and the 1200 amigas with some cool pictures.
Here's the website http://www.victortrucco.com/Commodor...toresAmiga.asp
I'll try to translate it for later on.

Here's another link for the same website but this time he uses two 512k memory chips from an old trident pc graphic card to had extra memory to an amiga 600 make it 2 Mb chip Ram instead of one, the only catch is that you can't use the expansion port anymore, but still very interisting.
http://www.victortrucco.com/Commodor...pansaoA600.asp

I hope this helps with the resurrection of some dead amigas.

[8bitbubsy]

He did quite a bad job on the Amiga 600, he broke off several pads and just twisted the caps off.

The A1200 job looked really good though!

[kipper2k]

I personally think twisting the caps off the SMD capacitors is a very bad idea, definately running the risk of lifting a pad. These motherboards are 20 years old and need a little TLC

[rkauer]

Twisting the capacitors will not break the pads, but wiggling them will do. If you look in the remarks I told Victor about it.

Simply use a small pair of pliers to crush the old capacitor and then twist it will break the legs with no harm to the board.

Since when I start to use this technique I never lifted a pad!

[kipper2k]

ok, i'll amend my previous thoughts, i just tried this method on an old board and i am really surprised at how easy they come off the board, just a slow steady twist of approx quarter of a turn is enough to break the legs of the cap and pop it off requiring a simple removal of the left over legs on the board, impressed.

[rkauer]

I told ya!

[TjLaZer]

Is this still recommended? Seems like a bad idea as a lot of these caps have leaked and corroded the pads making them very prone to lifting! I use hot air to remove them as I don't want to even risk it.

[Hewitson]

I personally wouldn't do it. I'd be wary of the hot air as well, a quick touch of a soldering iron should be all that's required.

This guy is clearly an amateur. He replaces the SMD caps with through hole parts. Very unprofessional.

[dlfrsilver]

SMD capacitors must be removed with hot tweezers. Best and easiest way to do it !

[Daedalus]

Hot air is fine as well, and flux will help greatly if there's already been some leakage. I wouldn't use a single soldering iron as you need to have both pads molten at the same time to safely remove a capacitor.

[ajk]

I used the twist method when recapping an oscilloscope from about 1992, so similar technology as the A1200. I got the scope for free so I didn't care about it all that much and there were a lot of caps so I thought it's worth the risk. No pads were torn off and the scope worked great after.

That said, I still don't do it with Amiga boards. Using two soldering irons is the least invasive (and still very fast) method I have found, occasionally hot air if there is a cap in a tight spot.

[Hewitson]

Originally Posted by Daedalus

Hot air is fine as well, and flux will help greatly if there's already been some leakage. I wouldn't use a single soldering iron as you need to have both pads molten at the same time to safely remove a capacitor.

I use a pair of pliers or tweezers and lift one side up at a time.

Edit: One downside of using hot air is that if you overheat the cap it will explode!

[Daedalus]

Originally Posted by Hewitson

I use a pair of pliers or tweezers and lift one side up at a time.

Yep, that's common enough, and stresses the remaining soldered pad. If the pad has already been weakened (e.g. by corrosion from electrolyte leakage), you risk peeling that pad off the board.

Edit: One downside of using hot air is that if you overheat the cap it will explode!

Indeed, if a capacitor has already died and pressure has built up inside the case then occasionally it can pop dramatically. That's pretty rare though, if it happens regularly it's an indication that your hot air is too hot. You shouldn't need to overheat a capacitor with hot air - they're designed to be soldered in a reflow oven so are capable of withstanding enough heat to melt solder. "Overheating" temperature varies with manufacturer, but is typically around 250-270 degrees, which is plenty for leaded solder (typically melts at 183 degrees).

[idrougge]

Originally Posted by Hewitson

I use a pair of pliers or tweezers and lift one side up at a time.

That's the quickest way to get tracelift. Whether you're desoldering or twisting them, always make sure you're not lifting it off the motherboard.

Originally Posted by Hewitson

Edit: One downside of using hot air is that if you overheat the cap it will explode!

Yep. Has happened to me before.

[Zippy Zapp]

I use the twist method and sometimes I cut them off (above the plastic retainer) if there is visible damage. You can say it is amateur but there are a few EEs that have made videos about it being somewhat safe.

I have recapped 7-10 Macs, A couple A1200s and several game systems this way and have yet to lift a pad. On the other hand, the first time I used a hot air station to remove SMD caps off a sound card I nuked about 4 pads on the one card. Same goes for trying to use a soldering iron to heat one side at a time and lift. That is just waiting to screw up a pad. The less times you heat the pads the better, IMHO.

[nexus]

that twist method is retarded and can cost you ripped pads
if its that difficult using normal methods then buy tweezer soldering iron
wont break the bank
and to the guy above have you used a microscope to inspect your work? im sure you cause damage to pads
you should never be heating pads long enough to hurt them fyi
this is why you must use solder and flux and have proper tips etc etc

only time these are ever a real pain is when you deal with non-leaded solder
eg like the caps used on your PC GPU's
many many bad guides vids online about soldering you should only trust the qualified people
youtube has many school vids on many many soldering techniques
also i would never trust a guide that replace SMD with through hole caps
they will rip the pads later

and also unlike the guy above heating 1 side will not hurt the pad
ripping and twisting is waaay worse
you tin your proper tip and use flux it should take few secs to melt the solder to slightly lift that 1 side of the pad
rinse repeat for the other side done and simple but like said above if that is too hard then please buy the tweezers or just use 2 irons and stop risking damage to these old boards

as a side note if you see that you cant melt the solder then you arent soldering right
you need to make sure your tip is cleaned and tinned and the iron has the correct temp set
and ofc you are using the correct tip for the job

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[nogginthenog]

Does anyone have any experience with these cheap Chinese tweezers?
https://www.aliexpress.com/item/Aoyu...829958281.html

@Zippy Zapp
Mr Carlson's Lab on youtube uses the twist method. He repairs a lot of old scopes and is clearly very knowledgeable. I wouldn't do that myself...

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[supaduper]

Originally Posted by nogginthenog

Does anyone have any experience with these cheap Chinese tweezers?
https://www.aliexpress.com/item/Aoyu...829958281.html

Yes I have those and they work fine but the just be gentle and dont use too much pressure with them as you will fracture the tips as with any soldering iron tip

[shaf]

I use the same unit and have never had any problems, Aoyue Products are fine for Hobbyists but won't hold up to constant daily use.

[nogginthenog]

Thanks, looks like it will work with my cheap solder station!