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Chuck(G)
April 9th, 2017, 01:01 PM
I thought that this video (https://www.youtube.com/watch?v=X8N9O3a9jiM) was pretty cool in that it shows an easy way to remove those nasty SMT electrolytics (Apple owners, take note).

I thought that sharing with the forum might be useful.

Al Kossow
April 9th, 2017, 02:22 PM
I thought that sharing with the forum might be useful.

just tried it on an SE/30 i was going to recap and it worked like a champ
you need to clean up some of the leads left on the pads

man, hadn't looked at this board in a while, a lot of corrosion on the smt ic leads :-(

MikeS
April 9th, 2017, 04:37 PM
I thought that this video (https://www.youtube.com/watch?v=X8N9O3a9jiM) was pretty cool in that it shows an easy way to remove those nasty SMT electrolytics (Apple owners, take note).

I thought that sharing with the forum might be useful.
Neat! Thanks for sharing the link!

Chuck(G)
April 9th, 2017, 05:16 PM
I have to admit that when he brought out the pliers and started twisting, I winced. :)

tingo
April 17th, 2017, 10:29 AM
I have to admit that when he brought out the pliers and started twisting, I winced. :)

Me too. But as he says, it saves time.

Unknown_K
April 17th, 2017, 02:24 PM
On old macs with major leaking you will end up removing solder pads doing this.

I just use snips and cut the capacitors in the middle then use pliers to remove the bottom half while holding the black base down (keeps you from ripping the pads off with the legs). Break the black base in half then remove the pieces, the legs take a second to desolder.

ScutBoy
April 18th, 2017, 07:53 AM
I just use snips and cut the capacitors in the middle then use pliers to remove the bottom half while holding the black base down (keeps you from ripping the pads off with the legs). Break the black base in half then remove the pieces, the legs take a second to desolder.

This has been my method as well. Makes me feel a bit less worried about pulling up a pad.

Hugo Holden
April 19th, 2017, 03:47 PM
I have removed and replaced a number of these capacitors in Tek 2465B oscilloscopes.

The electrolyte corrodes the soldering. It gets a thick grey oxide on it. In fact, any solder join that loses its shiny appearance, has had the electrolyte in contact with it. The electrolyte often leaks to a much larger area than seen a a first glance looking at a pcb. Oxides make good electrical insulators and also thermal insulators, so if the soldering iron is applied the solder joint may not heat up enough to melt the remaining metal solder.

The electrolyte also corrodes through the copper track(weakening the pads too) and also corrodes trough the films in surface mount resistors, making them go O/C.

The safest way to remove these surface mount electros is to scrape the tops of the solder join to see bare metal and apply some fresh solder, then using two small fine tip soldering irons (one in each hand) to heat both joins at the same time and lift/twist the capacitor using both irons as a tool, only when the solder is definitely melted. Otherwise the forces could cause the tracks to lift.

In gross cases of corrosion, where there is no solder left, probably the twist method is ok as the caps are about to fall off.

Here is a shocking fact : These capacitors are still in widespread use and as far as I can see the seals are no better, in nearly every appliance, automotive electronics etc. They guarantee failure of the apparatus in the 8 to 20 year time frame. The problem is so rampant I wonder if its deliberate/intentional. I think they should be banned/illegal. The damage from leaked electrolyte is catastrophic to the pcb and surrounding components. When I see these I replace them stat with surface mount Tantalum caps.

Unknown_K
April 19th, 2017, 05:37 PM
Motherboard manufacturers have moved to polymer SMT capacitors that don't leak.

Having leaks in 8-20 years when computers have a warranty of 1 to 3 years and life expectancy of maybe 5 years is not really an issue for 99% of people. People care about costs more then what happens to an item after they upgrade.

gertk
April 19th, 2017, 11:37 PM
A neat trick to see how far the 'disease' of the leaking capacitor has spread out is to illuminate the board with an UV lightsource.
The infested area is much better visible then and often much larger than you can see with the naked eye.

Juror22
April 24th, 2017, 10:21 AM
I'm going to try the UV light trick, next chance I get. The other trick for cap removal is a good tool - I've used most ways of cap removal, except for hot-air. Like all tools, the benefit lies in knowing when it will work and when it won't. Like previously mentioned, not all caps respond to this treatment, but a lot do.

For amateurs, be sure to practice removal techniques on a board (or boards) that you don't care about.