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Caps on multilayer boards

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  Caps on multilayer boards tabbypurr@gmail.com - 2016-11-07 04:12 -0800
    Re: Caps on multilayer boards Syd Rumpo <usenet@nononono.co.uk> - 2016-11-07 12:46 +0000
    Re: Caps on multilayer boards George Herold <gherold@teachspin.com> - 2016-11-07 06:13 -0800
      Re: Caps on multilayer boards tabbypurr@gmail.com - 2016-11-07 11:48 -0800
        Re: Caps on multilayer boards George Herold <gherold@teachspin.com> - 2016-11-07 13:00 -0800
    Re: Caps on multilayer boards Winfield Hill <hill@rowland.harvard.edu> - 2016-11-07 06:43 -0800
      Re: Caps on multilayer boards tabbypurr@gmail.com - 2016-11-07 11:46 -0800
        Re: Caps on multilayer boards Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2016-11-07 14:47 -0500
          Re: Caps on multilayer boards tabbypurr@gmail.com - 2016-11-07 11:57 -0800
            Re: Caps on multilayer boards stratus46 <stratus46@yahoo.com> - 2016-11-08 01:25 -0800
          Re: Caps on multilayer boards "Carl Ijames" <carl.ijamesXyZZy@ZZxyz.verizon.net> - 2016-11-07 16:11 -0500
            Re: Caps on multilayer boards tabbypurr@gmail.com - 2016-11-08 02:49 -0800
    Re: Caps on multilayer boards Jon Elson <jmelson@wustl.edu> - 2016-11-07 14:13 -0600
    Re: Caps on multilayer boards John S <Sophi.2@invalid.org> - 2016-11-07 18:58 -0600
    Re: Caps on multilayer boards Jeff Liebermann <jeffl@cruzio.com> - 2016-11-08 08:29 -0800
      Re: Caps on multilayer boards tabbypurr@gmail.com - 2016-11-08 13:32 -0800
        Re: Caps on multilayer boards Jeff Liebermann <jeffl@cruzio.com> - 2016-11-08 15:26 -0800
          Re: Caps on multilayer boards tabbypurr@gmail.com - 2016-11-08 15:40 -0800
    Re: Caps on multilayer boards Jasen Betts <jasen@xnet.co.nz> - 2016-11-10 04:29 +0000
      Re: Caps on multilayer boards tabbypurr@gmail.com - 2016-11-12 17:57 -0800
        Re: Caps on multilayer boards John S <Sophi.2@invalid.org> - 2016-11-12 20:23 -0600
          Re: Caps on multilayer boards tabbypurr@gmail.com - 2016-11-13 03:34 -0800
            Re: Caps on multilayer boards John S <Sophi.2@invalid.org> - 2016-11-13 10:17 -0600
              Re: Caps on multilayer boards tabbypurr@gmail.com - 2016-11-13 09:47 -0800

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#434128 — Caps on multilayer boards

What's the best way to remove the main body of electrolytic caps on multilayer boards so the remaining legs can be soldered to? I have some kit I don't want to extract from where it's fitted, with bad caps. Only the through hole component side is accessible.


NT

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#434131

On 07/11/2016 12:12, tabbypurr@gmail.com wrote:
> What's the best way to remove the main body of electrolytic caps on multilayer boards so the remaining legs can be soldered to? I have some kit I don't want to extract from where it's fitted, with bad caps. Only the through hole component side is accessible.
>
>
> NT
>

Assuming they're radial (or you wouldn't be asking), bend and wiggle 
until the legs fatigue, then solder to the pads?

Or drill in from the top wearing eye protection?

Cut (Dremel?) the can all the way round near the bottom?

Cheers
-- 
Syd

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#434138

On Monday, November 7, 2016 at 7:12:06 AM UTC-5, tabb...@gmail.com wrote:
> What's the best way to remove the main body of electrolytic caps on multilayer boards so the remaining legs can be soldered to? I have some kit I don't want to extract from where it's fitted, with bad caps. Only the through hole component side is accessible.
> 
> 
> NT

Two soldering irons and a helper to pull it?  (or push it out with a gravity assist.)

George H. 

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#434175

On Monday, 7 November 2016 14:13:09 UTC, George Herold  wrote:
> On Monday, November 7, 2016 at 7:12:06 AM UTC-5, tabbyp wrote:

> > What's the best way to remove the main body of electrolytic caps on multilayer boards so the remaining legs can be soldered to? I have some kit I don't want to extract from where it's fitted, with bad caps. Only the through hole component side is accessible.
> 
> Two soldering irons and a helper to pull it?  (or push it out with a gravity assist.)

What would I do with the soldering irons? Heat the capacitor can? I'm assuming you understood the question.


NT

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#434183

On Monday, November 7, 2016 at 2:48:17 PM UTC-5, tabb...@gmail.com wrote:
> On Monday, 7 November 2016 14:13:09 UTC, George Herold  wrote:
> > On Monday, November 7, 2016 at 7:12:06 AM UTC-5, tabbyp wrote:
> 
> > > What's the best way to remove the main body of electrolytic caps on multilayer boards so the remaining legs can be soldered to? I have some kit I don't want to extract from where it's fitted, with bad caps. Only the through hole component side is accessible.
> > 
> > Two soldering irons and a helper to pull it?  (or push it out with a gravity assist.)
> 
> What would I do with the soldering irons? Heat the capacitor can? I'm assuming you understood the question.
> 
> 
> NT

Sorry I did not understand.  If wiggling doesn't work harden and break the leads,
then as per Phil, de-cap it.  (Dremmel, grinding wheel and eye proection)  

George H.

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#434139

tabbypurr@gmail.com wrote...
>
> What's the best way to remove ...

 Pliers, blowtourch?


-- 
 Thanks,
    - Win

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#434173

On Monday, 7 November 2016 14:43:28 UTC, Winfield Hill  wrote:
> tabbypurr wrote...
> >
> > What's the best way to remove ...
> 
>  Pliers, blowtourch?

I don't know what I'd do with the blowtorch, I only have access to the topside. I assumed pulling with pliers might kill the PCB, but I may easily be wrong there.


NT

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#434174

On 11/07/2016 02:46 PM, tabbypurr@gmail.com wrote:
> On Monday, 7 November 2016 14:43:28 UTC, Winfield Hill  wrote:
>> tabbypurr wrote...
>>>
>>> What's the best way to remove ...
>>
>>  Pliers, blowtourch?
>
> I don't know what I'd do with the blowtorch, I only have access to the topside. I assumed pulling with pliers might kill the PCB, but I may easily be wrong there.
>
>
> NT
>

It sure might.  If wiggling doesn't work, can-opening sounds like the 
ticket.  If you have a board that's known to be dead anyway, you could 
try out a few techniques.

Cheers

Phil Hobbs

-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

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#434177

On Monday, 7 November 2016 19:48:02 UTC, Phil Hobbs  wrote:
> On 11/07/2016 02:46 PM, tabbypurr wrote:
> > On Monday, 7 November 2016 14:43:28 UTC, Winfield Hill  wrote:
> >> tabbypurr wrote...

> >>> What's the best way to remove ...
> >>
> >>  Pliers, blowtourch?
> >
> > I don't know what I'd do with the blowtorch, I only have access to the topside. I assumed pulling with pliers might kill the PCB, but I may easily be wrong there.
> 
> It sure might.  If wiggling doesn't work, can-opening sounds like the 
> ticket.  If you have a board that's known to be dead anyway, you could 
> try out a few techniques.
> 
> Cheers
> 
> Phil Hobbs

It's running but shuts down often, and I want to avoid risking the board. Cutting the can open with cutters is probably the best bet, I can't see soldering irons being useful.


NT

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#434220

On Monday, November 7, 2016 at 11:57:33 AM UTC-8, tabb...@gmail.com wrote:
> On Monday, 7 November 2016 19:48:02 UTC, Phil Hobbs  wrote:
> > On 11/07/2016 02:46 PM, tabbypurr wrote:
> > > On Monday, 7 November 2016 14:43:28 UTC, Winfield Hill  wrote:
> > >> tabbypurr wrote...
> 
> > >>> What's the best way to remove ...
> > >>
> > >>  Pliers, blowtourch?
> > >
> > > I don't know what I'd do with the blowtorch, I only have access to the topside. I assumed pulling with pliers might kill the PCB, but I may easily be wrong there.
> > 
> > It sure might.  If wiggling doesn't work, can-opening sounds like the 
> > ticket.  If you have a board that's known to be dead anyway, you could 
> > try out a few techniques.
> > 
> > Cheers
> > 
> > Phil Hobbs
> 
> It's running but shuts down often, and I want to avoid risking the board. Cutting the can open with cutters is probably the best bet, I can't see soldering irons being useful.
> 
> 
> NT

Is this a computer motherboard? If so a half fast repair technique isn't worth the bother. Just chuck it out. BUT To repair it you need a GOOD soldering iron and quite possibly a hot air soldering tool to to help your soldering iron. If the board has an internal power or ground plane without thermal reliefs, you won't be able to get enough heat through the lead to melt the solder all the way through. The hot air tool will help immensely. I've done it this way several times with 100 % success. 

G²

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#434184

I trimmed all the solder-side suggestions :-).  Way back when I was first 
learning how to solder onto pcb's I did some destructive testing on dead 
stuff just to find out how delicate things were, including ripping some 
radial electrolytic caps off of boards.  Now, these boards were 1970's 
vintage, 2 layer, definitely thicker than 1/16", with nice thick, wide 
copper traces and through hole plating.  I just pushed sideways on the top 
of the cap perpendicular to the line connecting the leads, to maximize the 
leverage.  Most times the leads started pulling through the capacitor body 
to give me 1/8-1/4" of slack, and then I could either reach in with little 
diagonal cutters or bend back and forth until the leads broke.  If it is 
working but you have the cap past maybe 30 degrees from vertical and still 
need to pull more lead out of the cap, stop and put a small screwdriver or 
other wedge under the cap on the side you are pushing towards and then push 
some more.  That keeps the leads as straight as possible so they come out of 
the cap with minimal force.  Some were tight to the board or wouldn't loosen 
up, and some of those I still managed to wiggle enough to break the leads 
but some did rip traces and through-hole plating off of the boards. 
Naturally since this was a test I'm sure the success rate was much higher 
than it would have been if I needed to save the boards :-).  You will have 
to look at your board and decide how rugged you think it is.  Multilayer is 
probably a good thing, since the plated through holes should be longer and 
thus more rugged.  Otherwise I think your only other option is to start 
cutting with a Dremel because I don't think you could gnaw through with wire 
cutters.  Practice on a free cap to see how bad it will be.  If you have 
room beside the cap I would use a cut off disc and cut maybe 1/16-1/8" above 
the board, just cutting the side wall all the way around if you can.   Then 
you should be able to pull up on the cap and start the foil unraveling 
inside until you can reach in with small dikes and cut it free.  If you have 
access to one side cut a line across the top and down one side to split the 
can open, and then start peeling.  You're going to make a mess with 
electrolyte and little metal bits on the board so cleanup will be critical 
and may be more effort than just giving in and dismounting the board.  Oh, 
the caps I was successfully destroying were in the 1/4-1/2" diameter range, 
rated maybe 6.3 to 35VDC.  I tried a couple of big AC caps, over 1" diameter 
and rated at least 125 VAC, and the leads and cap construction were way too 
much for the pcb so no joy at all with them.  I ripped maybe a dozen little 
caps off of a couple of scrapped TV boards, so more than one but not a huge 
sample size; it was a few minutes of good fun while I was supposed to be 
throwing away some junk :-).

-----
Regards,
Carl Ijames

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#434225

On Monday, 7 November 2016 21:12:08 UTC, Carl Ijames  wrote:
> I trimmed all the solder-side suggestions :-).  Way back when I was first 
> learning how to solder onto pcb's I did some destructive testing on dead 
> stuff just to find out how delicate things were, including ripping some 
> radial electrolytic caps off of boards.  Now, these boards were 1970's 
> vintage, 2 layer, definitely thicker than 1/16", with nice thick, wide 
> copper traces and through hole plating.  I just pushed sideways on the top 
> of the cap perpendicular to the line connecting the leads, to maximize the 
> leverage.  Most times the leads started pulling through the capacitor body 

Looks like you actually read the question, unlike a lot of replies. But most times isn't good enough here. I'll just do what I initially thought of and chew up the cap. Thanks everyone.


NT

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#434179

tabbypurr@gmail.com wrote:

> What's the best way to remove the main body of electrolytic caps on
> multilayer boards so the remaining legs can be soldered to? I have some
> kit I don't want to extract from where it's fitted, with bad caps. Only
> the through hole component side is accessible.
This seems like a mistake.  Use a soldering iron with lots of copper in the 
tip, for good heat conduction.  Apply tin-lead solder to the joint to dilute 
the (presumably) lead-free solder.  You can then use a solder sucker to 
remove as much old solder as you can, and re-apply tin-lead solder.  You 
need solder in the joint to conduct heat.  Then, heat the joint and work the 
cap to pull the lead back a little from that hole.  Go to the other lead and 
do the same.  Each time, you can pull the lead farther, it only takes 3 
cycles to completely remove the component.  Then, apply tin-lead solder, and 
you may have to use TWO soldering irons, one on each side of the board, and 
you can clear the solder from the holes.  Then, solder in the replacement.

I've done this on a number of PC motherboards.  It is fairly tedious, but 
only takes 5-10 minutes per cap.

Jon

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#434196

On 11/7/2016 6:12 AM, tabbypurr@gmail.com wrote:
> What's the best way to remove the main body of electrolytic caps on
> multilayer boards so the remaining legs can be soldered to? I have
> some kit I don't want to extract from where it's fitted, with bad
> caps. Only the through hole component side is accessible.


Try this video. This guy is pretty good at repair.

https://www.youtube.com/watch?v=X8N9O3a9jiM

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#434241

On Mon, 7 Nov 2016 04:12:02 -0800 (PST), tabbypurr@gmail.com wrote:

>What's the best way to remove the main body of electrolytic caps on multilayer 
>boards so the remaining legs can be soldered to? I have some kit I don't 
>want to extract from where it's fitted, with bad caps. Only the through 
>hole component side is accessible.

Here's one method for removing SMT electrolytics that requires no
soldering:
<https://www.youtube.com/watch?v=X8N9O3a9jiM>  (8:33)
Fast forward to 4:00 if you're in a hurry.


-- 
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

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#434286

On Tuesday, 8 November 2016 16:29:14 UTC, Jeff Liebermann  wrote:
> On Mon, 7 Nov 2016 04:12:02 -0800 (PST), tabbypurr wrote:

> >What's the best way to remove the main body of electrolytic caps on multilayer 
> >boards so the remaining legs can be soldered to? I have some kit I don't 
> >want to extract from where it's fitted, with bad caps. Only the through 
> >hole component side is accessible.
> 
> Here's one method for removing SMT electrolytics that requires no
> soldering:
> <https://www.youtube.com/watch?v=X8N9O3a9jiM>  (8:33)
> Fast forward to 4:00 if you're in a hurry.

They're through hole caps. I'll just chop them up.


NT

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#434301

On Tue, 8 Nov 2016 13:32:12 -0800 (PST), tabbypurr@gmail.com wrote:

>On Tuesday, 8 November 2016 16:29:14 UTC, Jeff Liebermann  wrote:
>> On Mon, 7 Nov 2016 04:12:02 -0800 (PST), tabbypurr wrote:
>
>> >What's the best way to remove the main body of electrolytic caps on multilayer 
>> >boards so the remaining legs can be soldered to? I have some kit I don't 
>> >want to extract from where it's fitted, with bad caps. Only the through 
>> >hole component side is accessible.

>> Here's one method for removing SMT electrolytics that requires no
>> soldering:
>> <https://www.youtube.com/watch?v=X8N9O3a9jiM>  (8:33)
>> Fast forward to 4:00 if you're in a hurry.

>They're through hole caps. I'll just chop them up.
>NT

I just knew that would be too easy.

I do quite a bit of "recapping" of motherboards with bulging caps.
These are the result of alternately heating each lead and "rocking"
the electrolytic away from the PCB:
<http://802.11junk.com/jeffl/pics/repair/slides/bad-caps.html>
However, that requires access to the PCB circuit side, which you
indicate is inaccessible.

These days, I chop off the can and pull out the leads one at a time,
with a little help from an antique desoldering station:
<http://802.11junk.com/jeffl/crud/pace-desoldering-station.jpg>
Again, this requires access to the PCB circuit side.

Occasionally, I try to extract the leads from the component side.  The
desoldering tool will not transfer enough heat through the PCB to melt
much of the solder on the circuit side.  To get decent heat transfer,
I have to add additional solder from the component side, which
hopefully will transfer enough heat to the circuit side to allow
extracting the leads.  Even if that works, there's usually some solder
splatter or dripping on the circuit side that needs touchup.

Also difficult is soldering a radial lead electrolytic to the PCB from
the component side.  You have to get the soldering iron tip under the
can of the electrolytic, which implies that the electrolytic is
elevated from the PCB at least the diameter of the soldering iron tip.
If you can do it without melting the covering on the electrolytic, and
nobody complain about the elevated capacitor and the aesthetics of
crappy soldering on the circuit side, you might get away with it.

If I'm really desperate, and don't care what it looks like, I leave
the remains of the original two wire leads soldered into the PCB and
just tack solder the replacement electrolytic to wherever it will fit.
I commonly do this when I don't have the proper can size or lead
spacing.  It's ugly, but works.

My apologies to John S. for posting the same URL.  I messed up the
read before write ritual.

-- 
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

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#434305

On Tuesday, 8 November 2016 23:26:15 UTC, Jeff Liebermann  wrote:
> On Tue, 8 Nov 2016 13:32:12 -0800 (PST), tabbypurr wrote:
> >On Tuesday, 8 November 2016 16:29:14 UTC, Jeff Liebermann  wrote:
> >> On Mon, 7 Nov 2016 04:12:02 -0800 (PST), tabbypurr wrote:
> >
> >> >What's the best way to remove the main body of electrolytic caps on multilayer 
> >> >boards so the remaining legs can be soldered to? I have some kit I don't 
> >> >want to extract from where it's fitted, with bad caps. Only the through 
> >> >hole component side is accessible.
> 
> >> Here's one method for removing SMT electrolytics that requires no
> >> soldering:
> >> <https://www.youtube.com/watch?v=X8N9O3a9jiM>  (8:33)
> >> Fast forward to 4:00 if you're in a hurry.
> 
> >They're through hole caps. I'll just chop them up.
> >NT
> 
> I just knew that would be too easy.
> 
> I do quite a bit of "recapping" of motherboards with bulging caps.
> These are the result of alternately heating each lead and "rocking"
> the electrolytic away from the PCB:
> <http://802.11junk.com/jeffl/pics/repair/slides/bad-caps.html>
> However, that requires access to the PCB circuit side, which you
> indicate is inaccessible.
> 
> These days, I chop off the can and pull out the leads one at a time,
> with a little help from an antique desoldering station:
> <http://802.11junk.com/jeffl/crud/pace-desoldering-station.jpg>
> Again, this requires access to the PCB circuit side.
> 
> Occasionally, I try to extract the leads from the component side.  The
> desoldering tool will not transfer enough heat through the PCB to melt
> much of the solder on the circuit side.  To get decent heat transfer,
> I have to add additional solder from the component side, which
> hopefully will transfer enough heat to the circuit side to allow
> extracting the leads.  Even if that works, there's usually some solder
> splatter or dripping on the circuit side that needs touchup.
> 
> Also difficult is soldering a radial lead electrolytic to the PCB from
> the component side.  You have to get the soldering iron tip under the
> can of the electrolytic, which implies that the electrolytic is
> elevated from the PCB at least the diameter of the soldering iron tip.
> If you can do it without melting the covering on the electrolytic, and
> nobody complain about the elevated capacitor and the aesthetics of
> crappy soldering on the circuit side, you might get away with it.
> 
> If I'm really desperate, and don't care what it looks like, I leave
> the remains of the original two wire leads soldered into the PCB and
> just tack solder the replacement electrolytic to wherever it will fit.
> I commonly do this when I don't have the proper can size or lead
> spacing.  It's ugly, but works.

I've done that last one at times. As long as it works. I tie the cap down so it's not unreliable mechanically.

> My apologies to John S. for posting the same URL.  I messed up the
> read before write ritual.


NT

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#434646

On 2016-11-07, tabbypurr@gmail.com <tabbypurr@gmail.com> wrote:
> What's the best way to remove the main body of electrolytic caps on multilayer boards so the remaining legs can be soldered to? I have some kit I don't want to extract from where it's fitted, with bad caps. Only the through hole component side is accessible.

long nose pliers: crush and pull

-- 
This email has not been checked by half-arsed antivirus software 

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#435261

On Thursday, 10 November 2016 05:01:20 UTC, Jasen Betts  wrote:
> On 2016-11-07, tabbypurr wrote:

> > What's the best way to remove the main body of electrolytic caps on multilayer boards so the remaining legs can be soldered to? I have some kit I don't want to extract from where it's fitted, with bad caps. Only the through hole component side is accessible.
> 
> long nose pliers: crush and pull

Too risky to the board.

I found chopping the cap up not effective, by the time I was down to the bottom its leads had snapped off from fatigue. The PCB pads are then so small, and their visibility so obscured by soldering iron & surrounding parts that I can't solder anything onto them. Fwiw the thing works just as well with the bad caps missing.

It looks like I have little option but to dismantle where this thing is and get it out. Ah well. When I have yet another tuit.


NT

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