Digest for sci.electronics.repair@googlegroups.com - 7 updates in 3 topics

9:45 AM Penedão 0 comments
oldschool@tubes.com: Aug 27 04:01AM -0500

On Sat, 25 Aug 2018 12:19:48 -0700, John Robertson <spam@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 <ohger1s@gmail.com>: Aug 27 06:41AM -0700

On Saturday, August 25, 2018 at 6:43:47 AM UTC-4, Gunther Heiko Hagen wrote:
 
> > Reforming is a fool's game.
 
> Throwing away is a fool's game.
 
> https://www.youtube.com/watch?v=nat1YYNMW5A
 
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 <curd@notformail.com>: Aug 27 02:09PM

On Mon, 27 Aug 2018 06:41:30 -0700, John-Del wrote:
 
> 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!
 
 
 
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Ralph Mowery <rmowery28146@earthlink.net>: Aug 27 12:30PM -0400

In article <pm10m4$dcc$1@dont-email.me>, curd@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.
jurb6006@gmail.com: Aug 26 04:50PM -0700

You might want to contact this guy on CL. He doesn't give a list but if you offer him more money he will probably try to find what you want.
 
https://cleveland.craigslist.org/ele/d/tubes-new/6668308516.html
jollymon1953@gmail.com: Aug 26 09:52AM -0700

On Wednesday, December 5, 2007 at 6:26:45 AM UTC-6, Brad wrote:
 
> Thanks in advance, Brad
 
> Before you type your password, credit card number, etc.,
> be sure there is no active keystroke logger (spyware) in your PC.
 
Like to ad a problem of my own. I'm a retired electronic tech (30+years) but have forgotten everything I knew about radios, AM/FM/SSB.
A friend has me looking at her Bose Wave, model AWr1-1W. All it puts out is an annoying loud buzz.Volume control do nothing. Even the power switch is useless. I did open it up, looked for loose connections, broken or burnt components, etc. Blew all the dust and dead bugs out.
Is it even worth repairing? Any idea as to the problem?
Thanks in advance.
jurb6006@gmail.com: Aug 26 11:51AM -0700

Not sure if it will help but electrotanya has one of them.
 
https://elektrotanya.com/bose_wave_radio_series_iii.pdf/download.html
 
Now listen, when you go to that site do not click any pictures, they all lead to junk. What you want is right under the picture on the left. It says "processing" and it makes you wait a minute or something like that. The word changes to "download". Click that and nothing else.
 
It used to change to "Get manual" but apparently they decided to change it.
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Digest for sci.electronics.repair@googlegroups.com - 3 updates in 1 topic

9:44 AM Penedão 0 comments
John-Del <ohger1s@gmail.com>: Aug 25 10:39AM -0700

On Saturday, August 25, 2018 at 9:32:35 AM UTC-4, Cursitor Doom wrote:
> 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 <curd@notformail.com>: Aug 25 06:23PM

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!
 
> 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.
 
 
 
 
 
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John Robertson <spam@flippers.com>: Aug 25 12:19PM -0700

On 2018/08/25 11:23 AM, Cursitor Doom wrote:
> 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.
 
John
 
 
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Digest for sci.electronics.repair@googlegroups.com - 9 updates in 1 topic

9:45 AM Penedão 0 comments
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Aug 24 01:18PM -0400


>> 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
 
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
 
--
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
Cursitor Doom <curd@notformail.com>: Aug 24 11:33PM

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).
 
 
 
 
 
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Cursitor Doom <curd@notformail.com>: Aug 24 11:42PM

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?
 
 
 
 
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tabbypurr@gmail.com: Aug 24 07:06PM -0700

On Saturday, 25 August 2018 00:42:23 UTC+1, Cursitor Doom wrote:
 
> 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 <rmowery28146@earthlink.net>: Aug 24 10:45PM -0400

In article <plpekd$ka7$1@dont-email.me>,
pcdhSpamMeSenseless@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 <spam@flippers.com>: Aug 24 10:04PM -0700

On 2018/08/22 2:36 PM, Ron D. wrote:
 
> 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.
 
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 <jdangus@att.net>: Aug 25 12:35AM -0500

On 8/24/18 6:42 PM, Cursitor Doom wrote:
> 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 <guntherxxx@quantserve.de>: Aug 25 10:43AM

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 <curd@notformail.com>: Aug 25 01:32PM

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. ;-)
 
 
 
 
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