Recapping

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retrogamac
Posts: 15
Joined: Mon Jan 21, 2019 7:52 pm

Recapping

Post by retrogamac » Sat Jan 26, 2019 12:19 pm

I got a Mac IIsi in good optical shape.
However, when I pressed the power button, it did not start.
Looking inside, I found that all of these PCB mounted silver pill electrolytic capacitors had emptied onto the board.

After my experience desoldering them, I really recommend one to do this only with good ventilation.
The vapors of this goo are really nasty.
To successfully remove the leaked goo, which had seeped under other parts, I had to bath and brush the board in an IPA-filled tub.

NOS stocks of the original leaky caps are available. But I am hesitant.

I am thinking of replacing them with normal mount radial low ESR caps, with the terminals cut short and bent so that they match the solder pads on the PCB. The problem now is that these original 47uF/16V pills are only 5 mm thick, and the common stock is thicker.

Any other users here who can tell of their recapping experiences?

that-ben
Posts: 40
Joined: Mon Dec 31, 2018 8:51 pm

Re: Recapping

Post by that-ben » Tue Jan 29, 2019 7:51 am

Electrolytic caps are a thing of the past that really shouldn't have existed in the first place, IMO. So many destroyed electronic equipment because of those :( Always go ahead and replace any electrolytic cap with a solid one the minute you acquire any old electronic device and live an happy life thereafter XD

MemoriMacfr
Posts: 20
Joined: Mon Dec 31, 2018 9:32 pm

Re: Recapping

Post by MemoriMacfr » Sun Feb 03, 2019 4:11 am

Hello
I agree with ben it must always change even if it does not leak.

they have a longevity of 10 years

and always work on an antistatic mat and have white cotton glove or (anti-static gan but it's expensive).

a welding station - de-welding of good quality, but there are versions made in china that are good.





https://www.ebay.fr/itm/XG-Z40-10cc-Pat ... 4121286908

https://www.ebay.fr/itm/Station-de-Soud ... 6a-bzGVSsA

DigiKey Electronics - Electronic Components Distributor US:

https://www.digikey.com/
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09838 Desco Static Control, ESD, Clean Room Products DigiKey

https://www.digikey.com/product-detail/ ... ND/3043259

16310 Desco Static Control, ESD, Clean Room Products DigiKey

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Aluminum Electrolytic Capacitors Capacitors DigiKey

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Fume, Smoke Extraction

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Hakko SOLDERING STATION 70W 120V 1691-1083-ND

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SOLDERING STATION WITH LCD DISPL 243-1228-ND

https://www.digikey.com/product-detail/ ... ND/5658763



Weller SOLDER STATION ANALOG 50W WES51-120V-ND

https://www.digikey.com/product-detail/ ... -ND/526397

PDQDev
Posts: 1
Joined: Mon Dec 31, 2018 10:14 pm

Re: Recapping

Post by PDQDev » Sun Feb 03, 2019 9:45 pm

^^ by welding, he means soldering. Translations.

Another thing to note, which recently bit me when recapping my Classic, is pay extra attention to the orientation of the replacements.
The stripe on an electrolytic cap indicates the negative side. (there are some where the stripe indicated the outermost roll, but that's a different story)
I replaced the surface mount electrolytics with some surface mount tantalums, making sure the stripe was on the same side.
Unfortunately, I learned too late that the stripe on the new tantalums indicates the positive side. :oops: I now have some troubleshooting to do on the analog board. :cry:

retrogamac
Posts: 15
Joined: Mon Jan 21, 2019 7:52 pm

Re: Recapping

Post by retrogamac » Mon Feb 04, 2019 1:35 am

@MemorMacfr
Yes these things are like time bombs.
Even if they haven't leaked visibly, they can corrode what is below them. Can be real nasty surprise!
And it is a royal shame that Apple used so short-lived caps!

@PDQDev
Ouch!
I got very very cautious in my youth already regarding electrolytic capacitors.
At about 16 years while an experiment I carelessly connected a 4700uF 40V cap the wrong way around.
It was dramatic.
I did the measurements in my circuit and then, all of a sudden, a loud BANG.
The whole corner of the room where I had my electronics desk was in a white cloud. All there was coated with a thin layer of capacitor fluid and fibers.
Cleanup took a while. I didn't find the capacitor, though.
I found its empty shell only years later when moving. It was behind a high cupboard.

I hope it was less spectacular on your Mac mobo...

Meanwhile I got new capacitors. Will make photos of the work!

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