Removing Large Electrolytics

[Cursitor Doom]

I have just spent about 40m trying to unsolder an electro on the board of
the Tek 466 I'm currently working on. It showed a ESR of 45 ohms so I
needed to hook it out of circuit just to be doubly sure it was really
that bad.
The electros in question are all fairly large ones in the (linear) PSU
section. For some reason they've not used separate boards for the various
sub-circuits, so the PSU is just one area of a v.large board which also
has components for all sorts of other functions. Anyway, The cap in
question has 5 connections to the board: 3 equi-spaced ground tabs around
the outside that come straight from the case of the cap and the 2 + and -
wires close to the centre. Given 5 in total through-hole connections,
it's proving very difficult to remove the cap using suction pump and
solder braid cos I cannot wiggle it at all. The best solution IMO would
be to heat all 5 tabs at the same time whilst pulling the cap's case from
the other side until it breaks free. Is there any tool that enables you
to do this? I fear the amount of fucking around I'm having to do
otherwise will lead to delamination of the PCB traces and an ugly mess.
I cannot even slip a junior hacksaw blade between the bottom of the cap
and the PCB and cut it free cos it's obscured by other components. :(



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[jf...@my-deja.com]

Some people use a butane torch to heat the solder joints gently while pulling on the component. Practice this technique before you do it on something you want to save. I have done this for DIP ICs.

Since you are pretty sure it is bad, I would clip the leads, destroying the can beforehand if necessary.

[tabb...@gmail.com]

On Wednesday, 22 August 2018 01:18:33 UTC+1, jf...@my-deja.com wrote:

> Some people use a butane torch to heat the solder joints gently while pulling on the component. Practice this technique before you do it on something you want to save. I have done this for DIP ICs.
>
> Since you are pretty sure it is bad, I would clip the leads, destroying the can beforehand if necessary.

A torch is a recipe for a badly burnt board. I've always been able to move a multi-legged component at least a tiny amount while melting one or more legs, and rock it back & forth, letting the board cool well if paper. The pcb is slightly flexible after all. Paper boards are weak, vulnerable to heat & the copper comes unglued when hot.

Maybe you could cut the 3 outer tabs off flush.


NT

[Phil Hobbs]

On 08/21/2018 07:46 PM, Cursitor Doom wrote:
> I have just spent about 40m trying to unsolder an electro on the board of
> the Tek 466 I'm currently working on. It showed a ESR of 45 ohms so I
> needed to hook it out of circuit just to be doubly sure it was really
> that bad.
> The electros in question are all fairly large ones in the (linear) PSU
> section. For some reason they've not used separate boards for the various
> sub-circuits, so the PSU is just one area of a v.large board which also
> has components for all sorts of other functions. Anyway, The cap in
> question has 5 connections to the board: 3 equi-spaced ground tabs around
> the outside that come straight from the case of the cap and the 2 + and -
> wires close to the centre. Given 5 in total through-hole connections,
> it's proving very difficult to remove the cap using suction pump and
> solder braid cos I cannot wiggle it at all. The best solution IMO would
> be to heat all 5 tabs at the same time whilst pulling the cap's case from
> the other side until it breaks free. Is there any tool that enables you
> to do this? I fear the amount of fucking around I'm having to do
> otherwise will lead to delamination of the PCB traces and an ugly mess.
> I cannot even slip a junior hacksaw blade between the bottom of the cap
> and the PCB and cut it free cos it's obscured by other components. :(
>
>
>

+1 for can-opening it to save wear and tear on the board. If you
measure 45 ohms ESR in-circuit, it won't be better by itself.

Cheers

Phil Hobbs

[Terry Schwartz]

Depending on what else is nearby, a heat gun can be effective.

[stra...@yahoo.com]

I use a Metcal which is a 40 Watt iron very well controlled but when removing caps from computer motherboards where there are no thermal reliefs to the ground plane, NO soldering iron can unsolder it alone. The pin can't conduct the heat fast enough. I also have a cheap Chinese hot air tool. Set the temp on the air tool slightly below the melt temp so it won't 'blow' any SMD parts (none on the 466) off the board. This becomes a 2 handed operation. While heating with the Metcal, I 'auxiliary' heat the board with the hot air tool for about 20 seconds. This WILL get hot enough to use your Edsyn Soldapullt to clear the hole and not lift any pads or damage the board.

Cutting up the cap and then removing the separate pins is OK IF you can destroy it without damaging the board. I've had excellent results with the aux heating technique which is faster than dismembering the part.

Torches are WAY too brutal especially in a Tek.

G²

[Cursitor Doom]

On Tue, 21 Aug 2018 21:28:10 -0400, Phil Hobbs wrote:

> +1 for can-opening it to save wear and tear on the board. If you
> measure 45 ohms ESR in-circuit, it won't be better by itself.

Well, it's hardly surprising for an electro of this age. Clearly the
original component from a scope with a s/n indicating it was manufactured
44 years ago! What was more surprising was that only 2 out of 6 electros
in the PSU section showed abnormal readings (the remaining faulty one has
gone leaky).

[tabb...@gmail.com]

On Wednesday, 22 August 2018 11:12:10 UTC+1, Cursitor Doom wrote:
> On Tue, 21 Aug 2018 21:28:10 -0400, Phil Hobbs wrote:
>
> > +1 for can-opening it to save wear and tear on the board. If you
> > measure 45 ohms ESR in-circuit, it won't be better by itself.
>
> Well, it's hardly surprising for an electro of this age. Clearly the
> original component from a scope with a s/n indicating it was manufactured
> 44 years ago! What was more surprising was that only 2 out of 6 electros
> in the PSU section showed abnormal readings (the remaining faulty one has
> gone leaky).

Sounds about par for the course. Go back further to paper caps and it'd be a surprise to find any still working properly. And yes, micamold were paper caps.


NT

[gghe...@gmail.com]

Right I'd hack up the component and pull pin by pin.
I do use a hot air rework station on some rotary switches...
it's faster than all that hacking.

George H.

[Cursitor Doom]

On Tue, 21 Aug 2018 21:54:12 -0700, stratus46 wrote:

> I use a Metcal which is a 40 Watt iron very well controlled but when
> removing caps from computer motherboards where there are no thermal
> reliefs to the ground plane, NO soldering iron can unsolder it alone.

You're not kidding. My largest iron is 40W/80W switchable. 40W won't
touch it and I'm not risking 80W! The biggest problem seems to be the cap
case - a long 1" dia aluminium tube with 3 tags at the bottom going
straight to PCB grounds. It's acting like a very effective heat sink.
Going to have to trash the caps from above.:(

[John-Del]

On Tuesday, August 21, 2018 at 7:46:24 PM UTC-4, Cursitor Doom wrote:
> I have just spent about 40m trying to unsolder an electro on the board of
> the Tek 466 I'm currently working on. It showed a ESR of 45 ohms so I
> needed to hook it out of circuit just to be doubly sure it was really
> that bad.
> The electros in question are all fairly large ones in the (linear) PSU
> section. For some reason they've not used separate boards for the various
> sub-circuits, so the PSU is just one area of a v.large board which also
> has components for all sorts of other functions. Anyway, The cap in
> question has 5 connections to the board: 3 equi-spaced ground tabs around
> the outside that come straight from the case of the cap and the 2 + and -
> wires close to the centre. Given 5 in total through-hole connections,
> it's proving very difficult to remove the cap using suction pump and
> solder braid cos I cannot wiggle it at all. The best solution IMO would
> be to heat all 5 tabs at the same time whilst pulling the cap's case from
> the other side until it breaks free. Is there any tool that enables you
> to do this? I fear the amount of fucking around I'm having to do
> otherwise will lead to delamination of the PCB traces and an ugly mess.
> I cannot even slip a junior hacksaw blade between the bottom of the cap
> and the PCB and cut it free cos it's obscured by other components. :(
>
>

You need to preheat the board. BTW, rocking a component while desoldering is a recipe for disaster if the board in question is a multi-layer. An internal foil can be separated from the plated-through hole if physical assertion is used.

If you can't remove the board to put it in a pre-heater, aim a hair dryer at it for about 10-15 minutes (a real heat gun can blister it). When the board is good and hot, it will have far less propensity to sink off heat from your soldering iron tip.

[Ron D.]

Once you remove the solder "ADD MORE". Yep, add more. Suck that out.

It has the tendency to heat other areas.

You can also add a solder removal alloy form Chip-Quik.

You can break off the tabs sometimes. You can cut the can sometimes. I'd use these methods at last resort.

Solder with a low temperature allow after removing most of the solder and suck out is my best suggestion.

[Phil Hobbs]

On 08/22/2018 06:12 AM, Cursitor Doom wrote:
> On Tue, 21 Aug 2018 21:28:10 -0400, Phil Hobbs wrote:
>
>> +1 for can-opening it to save wear and tear on the board. If you
>> measure 45 ohms ESR in-circuit, it won't be better by itself.
>
> Well, it's hardly surprising for an electro of this age. Clearly the
> original component from a scope with a s/n indicating it was manufactured
> 44 years ago! What was more surprising was that only 2 out of 6 electros
> in the PSU section showed abnormal readings (the remaining faulty one has
> gone leaky).

I have a Keithley 410 Micro-Microammeter from about 1960 that has all
its original electros and still works fine. Of course it uses an
electrometer tube, so it takes a good couple of hours' warm-up to settle
down on the 100-fA FS range, but it eventually does.

It has way more soul than my 610C(*), but really isn't nearly as good a
meter. (Don't anybody tell it, though--it has an honoured place on my
bench shelf.)

Cheers

Phil Hobbs

(*) "Now Nortons and Indians and Greeveses won't do...They don't have a
soul like a Vincent '52." -- Richard Thompson

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

[Baron]

Cursitor Doom prodded the keyboard with:

> On Tue, 21 Aug 2018 21:54:12 -0700, stratus46 wrote:
>
>> I use a Metcal which is a 40 Watt iron very well controlled but
>> when removing caps from computer motherboards where there are no
>> thermal reliefs to the ground plane, NO soldering iron can unsolder
>> it alone.
>
> You're not kidding. My largest iron is 40W/80W switchable. 40W won't
> touch it and I'm not risking 80W! The biggest problem seems to be
> the cap case - a long 1" dia aluminium tube with 3 tags at the
> bottom going straight to PCB grounds. It's acting like a very
> effective heat sink. Going to have to trash the caps from above.:(
>

Have you tried making a soldering bit with a piece of split copper
tube and a cooks torch to heat it. Apply to all the pins up at once.

--
Best Regards:
Baron.

[jf...@my-deja.com]

Some styles of electrolytics may be particularly difficult to remove gracefully. The ground tabs of the FP style were often twisted for mechanical stability before soldering. And sometimes, the pins were folded over before soldering.

[tabb...@gmail.com]

On Friday, 24 August 2018 02:24:43 UTC+1, jf...@my-deja.com wrote:

> Some styles of electrolytics may be particularly difficult to remove gracefully. The ground tabs of the FP style were often twisted for mechanical stability before soldering. And sometimes, the pins were folded over before soldering.

If enough solder is removed, twisted tabs can then be twisted back. A bit of remaining solder can be ignored, it lacks enough strength to get in the way. Folded over legs can be pushed up with a soldering iron before attempting removal.


NT

[Phil Hobbs]

This might be a good use for Chip Quik--it's a bismuth-based solder that
drops the liquidus point of a joint low enough that gentle use of a heat
gun will melt it.

Cheers

Phil Hobbs

[Cursitor Doom]

On Fri, 24 Aug 2018 13:18:02 -0400, Phil Hobbs wrote:

> This might be a good use for Chip Quik--it's a bismuth-based solder that
> drops the liquidus point of a joint low enough that gentle use of a heat
> gun will melt it.

I had to use one of these so-called multi-tools to slice through the
pins. There was about 2mm of clearance between the bottom of the caps and
the PCB. This is one of those cutters that vibrates from side to side at
high speed and the blade had *just* enough reach to cut through the most
inaccessible pins. Double checking after removal confirmed they had all
definitely failed (3 out of 6 altogether).

[Cursitor Doom]

I had 3 faulty electrolytics; all 30V/5500uF. In my spares bin I found 6
NOS (new old stock) electros of values 35V/3300uF which when stacked 2
high and wired in parallel occupy - fortunately - the same footprint as
the ones that failed.
These spares, though unused, are probably 40 years old. Will they need re-
forming gradually over 24hrs before installing?

[tabb...@gmail.com]

On Saturday, 25 August 2018 00:42:23 UTC+1, Cursitor Doom wrote:

> I had 3 faulty electrolytics; all 30V/5500uF. In my spares bin I found 6
> NOS (new old stock) electros of values 35V/3300uF which when stacked 2
> high and wired in parallel occupy - fortunately - the same footprint as
> the ones that failed.
> These spares, though unused, are probably 40 years old. Will they need re-
> forming gradually over 24hrs before installing?

I'd get newer ones if possible. At that age they'll be dead or near to it. In apps where high ESR is acceptable they last better, but still 40 is 80 human years for lytics.


NT

[Ralph Mowery]

In article <plpekd$ka7$1...@dont-email.me>,
pcdhSpamM...@electrooptical.net says...

>
>
> This might be a good use for Chip Quik--it's a bismuth-based solder that
> drops the liquidus point of a joint low enough that gentle use of a heat
> gun will melt it.
>
>
>

Just make sure you get the type that is made to help remove solder.
They make all kinds of solder type products. Some are just tin/lead and
will not help in removal.

From what little I have looked at it, the removal type is very
expensive .

[John Robertson]

I too like the idea of using a small amount of Chip-Qick after first
removing as much solder as possible. This may make the solder bond so
weak that it will break out with very little force. If not, then dig out
a heat gun and secure the board - heating the area and pull on the
capacitor at the same time, I've done that by tying a weight to the item
to remove and let gravity do the work while I fart around with the heat
gun, etc.

John

--
(Please post followups or tech inquiries to the USENET newsgroup)
John's Jukes Ltd.
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3
(604)872-5757 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

[Fox's Mercantile]

On 8/24/18 6:42 PM, Cursitor Doom wrote:
> I had 3 faulty electrolytics; all 30V/5500uF. In my spares bin I found 6
> NOS (new old stock) electros of values 35V/3300uF which when stacked 2
> high and wired in parallel occupy - fortunately - the same footprint as
> the ones that failed.
> These spares, though unused, are probably 40 years old. Will they need re-
> forming gradually over 24hrs before installing?

Reforming is a fool's game.
They either work to being with or they're bad.
That size isn't cheap, but if you buy new ones, that's the end of your
repair.

<https://www.mouser.com/ProductDetail/Vishay-Sprague/TVA1229?qs=%2fha2pyFadujX3auk1NrQ%2fV7hXwNYjanuW1qcIa3mLSA%3d>


--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

[Gunther Heiko Hagen]

On Sat, 25 Aug 2018 00:35:34 -0500, Fox's Mercantile wrote:

> Reforming is a fool's game.

Throwing away is a fool's game.

https://www.youtube.com/watch?v=nat1YYNMW5A

[Cursitor Doom]

On Fri, 24 Aug 2018 19:06:43 -0700, tabbypurr wrote:

> I'd get newer ones if possible. At that age they'll be dead or near to
> it. In apps where high ESR is acceptable they last better, but still 40
> is 80 human years for lytics.

I've always been of the view that it's excessive heat over long periods
of operation that eventually kills 'lytics. I don't see how them being in
store, albeit for many decades, could render them useless. But we shall
see! I'm currently reforming the NOS ones I have and will report back on
the results in due course.
Fortunately I'm not doing this for any customer; I'm only a hobbyist
working on my own stuff, so can easily afford to be proven wrong in this
if such should turn out to be the case. ;-)

[John-Del]

On Saturday, August 25, 2018 at 9:32:35 AM UTC-4, Cursitor Doom wrote:
> On Fri, 24 Aug 2018 19:06:43 -0700, tabbypurr wrote:
>
> > I'd get newer ones if possible. At that age they'll be dead or near to
> > it. In apps where high ESR is acceptable they last better, but still 40
> > is 80 human years for lytics.
>
> I've always been of the view that it's excessive heat over long periods
> of operation that eventually kills 'lytics. I don't see how them being in
> store, albeit for many decades, could render them useless. But we shall
> see! I'm currently reforming the NOS ones I have and will report back on
> the results in due course.
> Fortunately I'm not doing this for any customer; I'm only a hobbyist
> working on my own stuff, so can easily afford to be proven wrong in this
> if such should turn out to be the case. ;-)
>

Heat and charge cycles do affect a capacitor's life, but they're not the only factors. Humans who smoke, drink, and do drugs have a shorter life than those who don't, but we all will die eventually.

I've had plenty of electros in stock go off value, become leaky, and go up in ESR just from sitting in a nice quiet bin. I don't install any cap without running through my Z meter, and I will toss an entire lot of caps if one is bad.

[Cursitor Doom]

On Sat, 25 Aug 2018 10:39:13 -0700, John-Del wrote:

> Heat and charge cycles do affect a capacitor's life, but they're not the
> only factors. Humans who smoke, drink, and do drugs have a shorter life
> than those who don't, but we all will die eventually.

Hmmm. Not really a valid analogy!

> I've had plenty of electros in stock go off value, become leaky, and go
> up in ESR just from sitting in a nice quiet bin. I don't install any
> cap without running through my Z meter, and I will toss an entire lot of
> caps if one is bad.

I managed to find 8 electros in my bin that could used in parallel to get
the equivalent of the failed ones I've removed. I've checked them all for
ESR, leakage and Capacitance and the readings I've got have come out
indistinguishable from new caps of the same value & voltage rating. I've
picked the best 6 (with the lowest ESR) and am re-forming them over the
course of this weekend.
I'll report back in due course on the success (or failure) of this method.
I certainly wouldn't want to hit them with their rated voltage straight
away after so long in limbo as that *would* be inviting disaster.

[John Robertson]

On 2018/08/25 11:23 AM, Cursitor Doom wrote:
> On Sat, 25 Aug 2018 10:39:13 -0700, John-Del wrote:
>
>> Heat and charge cycles do affect a capacitor's life, but they're not the
>> only factors. Humans who smoke, drink, and do drugs have a shorter life
>> than those who don't, but we all will die eventually.
>
> Hmmm. Not really a valid analogy!
>
>> I've had plenty of electros in stock go off value, become leaky, and go
>> up in ESR just from sitting in a nice quiet bin. I don't install any
>> cap without running through my Z meter, and I will toss an entire lot of
>> caps if one is bad.
>
> I managed to find 8 electros in my bin that could used in parallel to get
> the equivalent of the failed ones I've removed. I've checked them all for
> ESR, leakage and Capacitance and the readings I've got have come out
> indistinguishable from new caps of the same value & voltage rating. I've
> picked the best 6 (with the lowest ESR) and am re-forming them over the
> course of this weekend.
> I'll report back in due course on the success (or failure) of this method.
> I certainly wouldn't want to hit them with their rated voltage straight
> away after so long in limbo as that *would* be inviting disaster.
>
>

The final test is leakage, set the cap up with an ammeter in series and
put it on a power supply running around 75% of the rated maximum
voltage. Leakage should be very low after the cap has stabilized.

Here is a nice write-up:

https://www.nmr.mgh.harvard.edu/~reese/electrolytics/

Heathkit made a great cap checker that we use to check older off the
shelf NOS caps. Has the Magic-Eye tube and everything - except ESR.

[olds...@tubes.com]

On Sat, 25 Aug 2018 12:19:48 -0700, John Robertson <sp...@flippers.com>
wrote:

>Heathkit made a great cap checker that we use to check older off the
>shelf NOS caps. Has the Magic-Eye tube and everything - except ESR.
>
>John

What is the model number of that Heathkit?

I ask because I have one of their cap testers, with an eye tube. I've
had it for a few years. I plugged it in when i got it and it lights up,
eye tube works, but I never put it to use. I'd tell you the model number
of mine, but I will have to dig it out of my storage shed.

[John-Del]

I won't watch that video because I KNOW Jeff is right: reforming is a fool's game. One may get away with reforming a cap to save a couple of bucks, but I'm more concerned about the collateral damage if this reformed cap returns to its leaky state and perhaps wipes out a power transformer.

[Cursitor Doom]

On Mon, 27 Aug 2018 06:41:30 -0700, John-Del wrote:

> I won't watch that video because I KNOW Jeff is right: reforming is a
> fool's game. One may get away with reforming a cap to save a couple of
> bucks, but I'm more concerned about the collateral damage if this
> reformed cap returns to its leaky state and perhaps wipes out a power
> transformer.

No one is suggesting trying to reform leaky capacitors!

[Ralph Mowery]

In article <pm10m4$dcc$1...@dont-email.me>, cu...@notformail.com says...

>
> No one is suggesting trying to reform leaky capacitors!
>
>
>
>

Doesn't the capacitors show the same effect as being leaky ?

From my understanding , the you start off at low voltage so the current
will not be very high and as the capacitor forms you up the voltage some
so the capacitor does not draw too much current.

My understanding is that the plates of the capacitor form a coating (for
not having a better word for it) on the plates when put under a DC
voltage.

I still believe in just replacing the 'bad' ones. Sometimes more harm
can be done to the equipment by doing the reforming process if done
wrong.

[John Robertson]

It is an IT-28. Has a Power Factor test which is useful for testing
power supply caps.

I can make a PDF of my manual if you are desperate...however I expect it
is online somewhere.

John :-#)#

[Cursitor Doom]

On Mon, 27 Aug 2018 12:30:26 -0400, Ralph Mowery wrote:

> Doesn't the capacitors show the same effect as being leaky ?
>
> From my understanding , the you start off at low voltage so the current
> will not be very high and as the capacitor forms you up the voltage some
> so the capacitor does not draw too much current.
>
> My understanding is that the plates of the capacitor form a coating (for
> not having a better word for it) on the plates when put under a DC
> voltage.
>
> I still believe in just replacing the 'bad' ones. Sometimes more harm
> can be done to the equipment by doing the reforming process if done
> wrong.

I don't think you've read the thread right through. These are NOS caps
out of circuit. I've now reformed them all and they pass all the
applicable tests, so I'll be installing them in place of the dead ones
later this week.

[Ralph Mowery]

In article <pm1jgs$gmf$1...@dont-email.me>, cu...@notformail.com says...

>
> > I still believe in just replacing the 'bad' ones. Sometimes more harm
> > can be done to the equipment by doing the reforming process if done
> > wrong.
>
> I don't think you've read the thread right through. These are NOS caps
> out of circuit. I've now reformed them all and they pass all the
> applicable tests, so I'll be installing them in place of the dead ones
> later this week.
>
>
>
>

It may be worth while on the NOS caps. I may even be tempted to give
that a try.

[Terry Schwartz]

Why you would put 40 year old caps into ANYTHING is beyond me. Reformed or not. They may "pass the tests" now but they will not hold up long term. Spend the $25 and get new parts. Unless, that is, you like doing things twice. Feel like risking that PCB again in 2 years?

[jf...@my-deja.com]

On Monday, August 27, 2018 at 12:50:00 PM UTC-7, Terry Schwartz wrote:
> ...Spend the $25 and get new parts...
Here in Silicon Valley, it would be a lot less. 4700uF/35V and 5600uF/42V are both available at retail for under US$1 each.

The diagnosis is probably correct, and the OP is committed to replacing the original caps, but I do not remember seeing a claim that this actually fixed the problem. At this price and given the concern over the long term reliability of the junque-box parts, I would tack-solder these caps to verify that this does indeed fix the problem, but I would use the new parts for the "permanent" repair. Using reformed parts would be OK if the faulty ones were unobtanium.

[Fox's Mercantile]

On 8/27/18 8:41 AM, John-Del wrote:
> I won't watch that video because I KNOW Jeff is right: reforming
> is a fool's game.

Like John, I do this shit for a living, and I refuse to waste my
time, or reputation, with any "crack pot" repairs.

[Cursitor Doom]

On Mon, 27 Aug 2018 20:56:41 -0500, Fox's Mercantile wrote:

> On 8/27/18 8:41 AM, John-Del wrote:
>> I won't watch that video because I KNOW Jeff is right: reforming is a
>> fool's game.
>
> Like John, I do this shit for a living, and I refuse to waste my time,
> or reputation, with any "crack pot" repairs.

If you're a professional repair tech, I can see why you would only use
new parts. But I'm just a ham; a hobbyist. And we hams have been
successfully reforming electros for many decades without any adverse
outcomes. Loads of info on the net it you care to look for it, but I'm
guessing since you're a pro you'll turn your nose up at the very thought!

[peterw...@gmail.com]

And we hams have been
successfully reforming electros for many decades without any adverse
outcomes.

That have been reported. Hams are a parsimonious lot. And, like many of us, they will refrain from publicizing silly mistakes.

Peter Wieck
Melrose Park, PA

[Fox's Mercantile]

On 8/28/18 4:15 AM, Cursitor Doom wrote:
> If you're a professional repair tech, I can see why you would
> only use new parts. But I'm just a ham; a hobbyist. And we
> hams have been successfully reforming electros for many decades
> without any adverse outcomes. Loads of info on the net it you
> care to look for it, but I'm guessing since you're a pro you'll
> turn your nose up at the very thought!

Hams are notoriously cheap.
And the internet is a cesspool of useless information.

I've been a licensed Ham for 50 years now.
You wouldn't believe some of the butchery I've encountered on
Ham radio gear. I have a phrase for it. Joe "Claw Hammer" Ham
has been here. Apparently having a ham license gives you the
ability to think you know more than any commercial engineer.

That being said, I've used old NOS capacitors for myself.
But I don't waste my time reforming them. They either work right
the first time they have power applied or they don't.

[mako...@yahoo.com]

if there is room, just leave the old cap in place and wire a new one in parallel.

m

[John Robertson]

On 2018/08/28 6:43 AM, mako...@yahoo.com wrote:
> if there is room, just leave the old cap in place and wire a new one in parallel.
>
> m
>
>

That is only good advice if you first cut the old cap out of circuit.
Many capacitors fail by increasing their leakage or outright shorting out.

If the capacitor is suspect replace it.

John :-#(#

[Ralph Mowery]

In article <RrWdnRKU77hVrRjG...@giganews.com>,
jda...@att.net says...

>
> Hams are notoriously cheap.
> And the internet is a cesspool of useless information.
>
> I've been a licensed Ham for 50 years now.
> You wouldn't believe some of the butchery I've encountered on
> Ham radio gear. I have a phrase for it. Joe "Claw Hammer" Ham
> has been here. Apparently having a ham license gives you the
> ability to think you know more than any commercial engineer.
>
> That being said, I've used old NOS capacitors for myself.
> But I don't waste my time reforming them. They either work right
> the first time they have power applied or they don't.
>
>

I understand that # 40 wire was made by 2 hams arguing over a penny.

I have only been a ham for 45 years. I like you have seen many things
cobbled together. Have even done some of that myself. Not that I
thought I was a better engineer,but because I only had so much money to
do things. Those were projects for myself.

If I am doing things for myself, I may do anything to get equipment
going. If I were doing things for others, it would be with good parts.
Like the time at work an outside repair person came in to repair a 3
phase motor drive unit. He found 2 out of 3 diodes bad. I told him to
replace the 3 rd one. It may have been under stress or not. He said
they were $ 200 each. Told him it costs us $ 1000 or more per hour
while that equipment was down, so $ 200 is good insurance it will not
quit in a short time.
That 3 rd diode would probably last , but why take a chance at those
rates.

[peterw...@gmail.com]

On Tuesday, August 28, 2018 at 9:43:42 AM UTC-4, mako...@yahoo.com wrote:
> if there is room, just leave the old cap in place and wire a new one in parallel.
>
> m

And when the old one fails short?

[Cursitor Doom]

On Tue, 28 Aug 2018 11:07:13 -0400, Ralph Mowery wrote:

> If I am doing things for myself, I may do anything to get equipment
> going. If I were doing things for others, it would be with good parts.
> Like the time at work an outside repair person came in to repair a 3
> phase motor drive unit. He found 2 out of 3 diodes bad. I told him to
> replace the 3 rd one. It may have been under stress or not. He said
> they were $ 200 each. Told him it costs us $ 1000 or more per hour
> while that equipment was down, so $ 200 is good insurance it will not
> quit in a short time.
> That 3 rd diode would probably last , but why take a chance at those
> rates.

And that is the very core of this issue: economics. As a hobbyist, I'm
only fixing up my own stuff and if it goes wrong again in a couple of
years owing to the NOS parts I used having failed - I don't believe they
will for a moment but simply for the sake of argument - then it's no big
deal at all for me.
It's a totally different story for professional repairers who would be
foolish indeed to install anything other than good quality new parts from
a reputable supplier. Sure it costs more, but for a pro, it's well worth
it for all sorts of reasons.

[Cursitor Doom]

On Wed, 22 Aug 2018 04:03:23 -0700, tabbypurr wrote:

> Sounds about par for the course. Go back further to paper caps and it'd
> be a surprise to find any still working properly. And yes, micamold were
> paper caps.

I've got a box full of the oil & paper caps that come in cubiod cans and
they all tested fine (I have an awful lot of vintage spares here). Not so
sure about the tubular paper caps which I assume you're talking about,
though.

[Gunther Heiko Hagen]

On Mon, 27 Aug 2018 14:02:45 -0700, jf...@my-deja.com wrote:

> On Monday, August 27, 2018 at 12:50:00 PM UTC-7, Terry Schwartz wrote:
>> ...Spend the $25 and get new parts...
> Here in Silicon Valley, it would be a lot less. 4700uF/35V and
> 5600uF/42V are both available at retail for under US$1 each.

Can you kindly provide a link to the supplier you refer to who's able to
offer such truly extraordinary prices?

[jf...@my-deja.com]

Anchor Electronics, 2040 Walsh Avenue, Santa Clara, California 95050 USA
http://www.anchor-electronics.com/

https://anchor-electronics.com/price-list.pdf

Electrolytic capacitors are on page 13.

I am a retail, over-the-counter customer. I do not know about their mail order policies, except the last page of the price list says "We Ship To USA & Canada Addresses Only."

[Gunther Heiko Hagen]

On Tue, 28 Aug 2018 14:14:36 -0700, jf...@my-deja.com wrote:

> Anchor Electronics, 2040 Walsh Avenue, Santa Clara, California 95050
> USA http://www.anchor-electronics.com/
>
> https://anchor-electronics.com/price-list.pdf
>
> Electrolytic capacitors are on page 13.
>
> I am a retail, over-the-counter customer. I do not know about their
> mail order policies, except the last page of the price list says "We
> Ship To USA & Canada Addresses Only."

Very interesting.... many thanks for that.

[Phil Hobbs]

On 08/28/2018 01:47 PM, Cursitor Doom wrote:
> On Wed, 22 Aug 2018 04:03:23 -0700, tabbypurr wrote:
>
>> Sounds about par for the course. Go back further to paper caps and it'd
>> be a surprise to find any still working properly. And yes, micamold were
>> paper caps.
>
> I've got a box full of the oil & paper caps that come in cubiod cans and
> they all tested fine (I have an awful lot of vintage spares here). Not so
> sure about the tubular paper caps which I assume you're talking about,
> though.

Moisture + acid paper + foil = mess. That'll take a lot longer if the
cap has metal on five sides.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

[tabb...@gmail.com]

On Saturday, 1 September 2018 20:48:34 UTC+1, Phil Hobbs wrote:
> On 08/28/2018 01:47 PM, Cursitor Doom wrote:
> > On Wed, 22 Aug 2018 04:03:23 -0700, tabbypurr wrote:
> >
> >> Sounds about par for the course. Go back further to paper caps and it'd
> >> be a surprise to find any still working properly. And yes, micamold were
> >> paper caps.
> >
> > I've got a box full of the oil & paper caps that come in cubiod cans and
> > they all tested fine (I have an awful lot of vintage spares here). Not so
> > sure about the tubular paper caps which I assume you're talking about,
> > though.
>
> Moisture + acid paper + foil = mess. That'll take a lot longer if the
> cap has metal on five sides.
>
> Cheers
>
> Phil Hobbs

My prewar metal can paper caps are all wax sealed, and every last one tested dead as a very dead thing. The non-metal seal is where it can go wrong. Not sure why they didn't use bitumen.


NT

[whit3rd]

On Friday, August 24, 2018 at 10:35:43 PM UTC-7, Fox's Mercantile wrote:
> On 8/24/18 6:42 PM, Cursitor Doom wrote:
> > I had 3 faulty electrolytics; all 30V/5500uF. In my spares bin I found 6
> > NOS (new old stock) electros ...
> > These spares, though unused, are probably 40 years old. Will they need re-
> > forming gradually over 24hrs before installing?
>
> Reforming is a fool's game.
> They either work to being with or they're bad.

That's not ny experience; yes, I might toss the 40--year-olds, but only
because new ones are cheap and probably better performing.
Even one-year-old capacitors can benefit from reforming, though,
and for some uses (timing capacitors) it's beneficial.

It doesn't take 24 hours, though: with a current-limited supply, just
give 'em 150% of the rated voltage and warm 'em with a hair
dryer for a few minutes, while watching the leakage current.
You can see it drop from milliamps to microamps.

[Fox's Mercantile]

On 9/2/18 3:15 AM, whit3rd wrote:
> It doesn't take 24 hours, though: with a current-limited supply, just
> give 'em 150% of the rated voltage and warm 'em with a hair
> dryer for a few minutes, while watching the leakage current.
> You can see it drop from milliamps to microamps.

That's not how manufacturing does it.
Their installed and at the end of assembly line, full power is applied.
They either work or they don't.

[Stephen Wolstenholme]

On Sun, 2 Sep 2018 06:03:04 -0500, Fox's Mercantile <jda...@att.net>
wrote:

>On 9/2/18 3:15 AM, whit3rd wrote:
>> It doesn't take 24 hours, though: with a current-limited supply, just
>> give 'em 150% of the rated voltage and warm 'em with a hair
>> dryer for a few minutes, while watching the leakage current.
>> You can see it drop from milliamps to microamps.
>
>That's not how manufacturing does it.
>Their installed and at the end of assembly line, full power is applied.
>They either work or they don't.

I remember when part of my job was fixing power supplies. Some that
failed the automatic part of the test last thing on one day would work
the day after.

I never found out why that happened but I assumed it was an
electrolytic so I changed the lot.

Steve

--
http://www.npsnn.com

[Cursitor Doom]

On Sun, 02 Sep 2018 06:03:04 -0500, Fox's Mercantile wrote:

> That's not how manufacturing does it.
> Their installed and at the end of assembly line, full power is applied.
> They either work or they don't.

That's all very well for *brand new* capacitors!

[+++ATH0]

On 2018-08-28 10:47, Cursitor Doom wrote:
> On Wed, 22 Aug 2018 04:03:23 -0700, tabbypurr wrote:
>
> I've got a box full of the oil & paper caps that come in cubiod cans and
> they all tested fine (I have an awful lot of vintage spares here).

Enjoy your PCBs.

[tabb...@gmail.com]

and not the good type


NT

[whit3rd]

On Sunday, September 2, 2018 at 4:45:44 AM UTC-7, Stephen Wolstenholme wrote:
> On Sun, 2 Sep 2018 06:03:04 -0500, Fox's Mercantile <jda...@att.net>
> wrote:

[about electrolytic capacitors]

> >Their installed and at the end of assembly line, full power is applied.
> >They either work or they don't.
>
> I remember when part of my job was fixing power supplies. Some that
> failed the automatic part of the test last thing on one day would work
> the day after.
>
> I never found out why that happened but I assumed it was an
> electrolytic so I changed the lot.

Electrolytics have to be formed (kept under bias for a period) before they
develop the dielectric (oxide) layer, AND that layer is continuously
renewed when they're under bias. On the shelf, however, it degrades.
Some switchmode power supplies (the old Apple II types) rely on
timing capacitors for startup sequencing, and the power filter electrolytics are
NOT the prime suspects when such a power supply doesn't work.

You can often fix those power supplies by leaving 'em turned on overnight.
The most plausible reason for this is that the timing capacitors (not the big
filter caps) have to be re-formed. This syndrome can't be improved with
new filter capacitors (I've tried). Once they work, they're reliable again.

[~misfit~]

Once upon a time on usenet John Robertson wrote:
> On 2018/08/25 11:23 AM, Cursitor Doom wrote:
>> On Sat, 25 Aug 2018 10:39:13 -0700, John-Del wrote:
>>
>>> Heat and charge cycles do affect a capacitor's life, but they're
>>> not the only factors. Humans who smoke, drink, and do drugs have a
>>> shorter life than those who don't, but we all will die eventually.
>>
>> Hmmm. Not really a valid analogy!
>>
>>> I've had plenty of electros in stock go off value, become leaky,
>>> and go up in ESR just from sitting in a nice quiet bin. I don't
>>> install any cap without running through my Z meter, and I will toss
>>> an entire lot of caps if one is bad.
>>
>> I managed to find 8 electros in my bin that could used in parallel
>> to get the equivalent of the failed ones I've removed. I've checked
>> them all for ESR, leakage and Capacitance and the readings I've got
>> have come out indistinguishable from new caps of the same value &
>> voltage rating. I've picked the best 6 (with the lowest ESR) and am
>> re-forming them over the course of this weekend.
>> I'll report back in due course on the success (or failure) of this
>> method. I certainly wouldn't want to hit them with their rated
>> voltage straight away after so long in limbo as that *would* be
>> inviting disaster.
>
> The final test is leakage, set the cap up with an ammeter in series
> and put it on a power supply running around 75% of the rated maximum
> voltage. Leakage should be very low after the cap has stabilized.
>
> Here is a nice write-up:
>
> https://www.nmr.mgh.harvard.edu/~reese/electrolytics/
>
> Heathkit made a great cap checker that we use to check older off the
> shelf NOS caps. Has the Magic-Eye tube and everything - except ESR.

Thanks for that link.
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)