Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives :: Books
Support This Site: Contributors :: Advertise


It is currently Jan Tue 23, 2018 4:53 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 14 posts ] 
Author Message
 Post subject: Re-stuffing aluminum can question
PostPosted: Feb Fri 28, 2014 8:40 pm 
Member
User avatar

Joined: Jan Mon 18, 2010 2:13 am
Posts: 15536
Location: Dayton Ohio
I may have answered my own question, but I wanted to run this by the likes of y'all to see if I missed anything. :wink: :D

In re-stuffing an electrolytic cap, I need to make good solid electrical connection to the aluminum can from within. Soldering to aluminum can be done, but it requires an oxygen free environment to do so.
As direct contact between copper and aluminum is a bad idea, I need a metal that will go between. I see that electrical panels will often use tin plating on the buss bars to interface the two metal, I was wondering about zinc?

Solder a wire to a zinc plated steel washer, put it against the aluminum and sandwich it in as shown in the drawing below.
As I only want to do this ONCE, I wanted to do it right. As such I am NOT using an electrolytic cap as replacement, but a metal film polypropylene Solen Fast capacitor.

Well, the large nut at the bottom is certainly a steel nut that is probably plated with either zinc or cadmium. Zinc is rather close to aluminum as far as electrode potential is concerned, so I feel it should be a good choice. I just need to somehow clean off the bottom end of the inside of the can very well.

Thanks in advance for any thoughts. :idea:

-Steve


Attachments:
22-119cap.jpg
22-119cap.jpg [ 25.74 KiB | Viewed 1749 times ]
aluminum-electrolytic-can.jpg
aluminum-electrolytic-can.jpg [ 53.13 KiB | Viewed 1749 times ]

_________________
Radio Interests
-Zenith
-Sparton
-Pre-War FM
Consoles and floor models, the bigger, the better!
Top
 Profile  
 
 Post subject: Re: Re-stuffing aluminum can question
PostPosted: Feb Fri 28, 2014 9:19 pm 
Member
User avatar

Joined: Jan Fri 06, 2012 8:47 pm
Posts: 6243
I must be missing something.

Where is the capacitor and how is it connecting to the outside world?

Curtis Eickerman

_________________
http://curtiseickerman.weebly.com


Top
 Profile  
 
 Post subject: Re: Re-stuffing aluminum can question
PostPosted: Feb Fri 28, 2014 9:46 pm 
Member

Joined: Feb Sun 24, 2008 4:21 am
Posts: 4607
Location: Sedona, AZ/ Placentia CA
Steve, I think I understand what your trying to do. Keep both cap wires attached inside the can? I have never worked on one just like that. Personally, I would go to ACE or somewhere and after removing the bolt/nut assembly, see if I could find some brass washers for the two internal ones. Perhaps a new rubber one as well. You should be able to solder a small tab on the perimeter of each washer sticking out to the side. This would allow you a solder point for the wires from your Solen. Needless to say, clean the bottom inside of the can well so the washer makes good contact. Reassemble and tighten the nut and bolt firmly. Check for any shorts . I would not mess around getting a good contact (solder) on the existing washers.
Although I didn't see it in your picture, one of those very large star washers between the chassis and can for when you tighten the can to the chassis.
Hope this helps.
Edit: It does beg the question Steve, how was the original cap attached?
Jerry

_________________
A friend in need is a pest. Bill Slee ca 1972


Top
 Profile  
 
 Post subject: Re: Re-stuffing aluminum can question
PostPosted: Feb Fri 28, 2014 10:09 pm 
Member
User avatar

Joined: Jan Mon 18, 2010 2:13 am
Posts: 15536
Location: Dayton Ohio
Here is another drawing to help.

The only thing original in the drawing is the old aluminum electrolytic can and the fiber insulating washer on the bottom next to the nut. The bolt, washers and insulating rubber washer are new.
True, I left out the star washer and big nut that attach the finished cap to the chassis.

Also, I have an insulating nylon standoff that holds the bolt centered in the hole that is not shown in the drawing. I hope this clears up any confusion as to what I'm doing. :D

I am surprised how badly pitted and corroded the inside of the can is. I'm using a Dremel type tool with a flexible extension which fits within the top hole in the can.
It has a cupped wire brush which I've been working away at the corrosion.

Gotta have good ventilation <cough cough> :wink:

Thanks for the thoughts!

-Steve


Attachments:
aluminum-electrolytic-can2.jpg
aluminum-electrolytic-can2.jpg [ 61.36 KiB | Viewed 1716 times ]

_________________
Radio Interests
-Zenith
-Sparton
-Pre-War FM
Consoles and floor models, the bigger, the better!
Top
 Profile  
 
 Post subject: Re: Re-stuffing aluminum can question
PostPosted: Feb Fri 28, 2014 10:17 pm 
Moderator

Joined: Jan Thu 01, 1970 1:00 am
Posts: 25943
Location: Detroit, MI USA
Some people just solder insulated wires onto both leads of the new cap then run them through the empty center hole and solder to the connection points in the chassis after the can is mounted. Not 100% authentic, but they did make plenty of aftermarket replacement screw base electrolytics exactly that way.

_________________
Dennis

Experience is what you gain when the results aren't what you were expecting.


Top
 Profile  
 
 Post subject: Re: Re-stuffing aluminum can question
PostPosted: Feb Fri 28, 2014 10:36 pm 
Member
User avatar

Joined: Jan Mon 18, 2010 2:13 am
Posts: 15536
Location: Dayton Ohio
Thanks, Dennis, that is true.

I suppose my only real reason for posting was if anyone thought it would be a bad idea to use a zinc plated steel washer to make electrical contact with the inside of the aluminum can?
Or if another metal would be preferable?

I may give in and run wires through the hole...

-Steve

_________________
Radio Interests
-Zenith
-Sparton
-Pre-War FM
Consoles and floor models, the bigger, the better!


Top
 Profile  
 
 Post subject: Re: Re-stuffing aluminum can question
PostPosted: Feb Fri 28, 2014 11:20 pm 
Member

Joined: Feb Sun 24, 2008 4:21 am
Posts: 4607
Location: Sedona, AZ/ Placentia CA
Steve, wires through the hole are the way to go. A lot of heat shrink as needed on some nice insulated wire. Sorry, I thought the arrangement you had shown was original. As Dennis indicated some long wires to pick up a good ground and perhaps a terminal strip to mount the B+ lines to. The "bolt" is not the way to go.
Best, Jerry

_________________
A friend in need is a pest. Bill Slee ca 1972


Top
 Profile  
 
 Post subject: Re: Re-stuffing aluminum can question
PostPosted: Mar Sat 01, 2014 2:20 am 
Member
User avatar

Joined: Jan Mon 18, 2010 2:13 am
Posts: 15536
Location: Dayton Ohio
Alright, No problem. Thanks for the advice! :D

Though, I'm curious as to why you think the bolt is a bad idea? The only weak link I see is the connection between the washer and the aluminum can.

I didn't want to use the original bolt as it itself is made of aluminum and the rubber insulation around it was crumbling. I was going to use a new 1/4" 28 bolt so i could use the original nut and connection lug.

-Steve

_________________
Radio Interests
-Zenith
-Sparton
-Pre-War FM
Consoles and floor models, the bigger, the better!


Top
 Profile  
 
 Post subject: Re: Re-stuffing aluminum can question
PostPosted: Mar Sat 01, 2014 2:50 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 30698
Location: Pocasset, Cape Cod, MA
I doubt you'd have any problem with an inside washer, whatever its material. I would however be tempted to drill a small hole on the bottom of the can near the edge and run a bare wire through that for the negative lead.


Top
 Profile  
 
 Post subject: Re: Re-stuffing aluminum can question
PostPosted: Mar Sat 01, 2014 3:06 am 
Moderator

Joined: Jan Thu 01, 1970 1:00 am
Posts: 25943
Location: Detroit, MI USA
I wonder if you could find a really large solder lug for the inside, and a couple of toothed washers to bite into the aluminum can?

_________________
Dennis

Experience is what you gain when the results aren't what you were expecting.


Top
 Profile  
 
 Post subject: Re: Re-stuffing aluminum can question
PostPosted: Mar Sat 01, 2014 5:48 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 7091
Location: Portland Oregon
I have always used the bolt method but drilled a hole through it for both wires. I guess you could use the hollow threaded screws they use for lamps and anchor it down that way. I prefer the idea of the wires coming through the can over powering the bolt and washers up.
Ed


Top
 Profile  
 
 Post subject: Re: Re-stuffing aluminum can question
PostPosted: Mar Sat 01, 2014 7:47 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2973
Location: Seattle WA US
When I first restuffed capacitors, I tried to use copper plating techniques to make a solder contact to the aluminum can. I failed miserably.

My solution was to keep the aluminum out of the direct circuit. Drill a hole thru the bottom of the can to allow a tinned copper ground wire to pass thru and be soldered to a copper washer or solder lug outside the can. Allow the aluminum can to make mechanical contact with the washer and chassis, so you don't have any stray potential problems, but don't depend on any kind of connection to the aluminum to carry current.

For your one-hole mount capacitor with a single conductor center post, I would place a tinned copper washer between the aluminum can and the chassis, out of sight when the can was installed. I would drill straight throught the can and solder the ground lead from the new caps in the can to the washer. I would also notch the threaded mounting boss of the can and bring a lead down that notch to connect the copper washer to the power supply dc ground at the same point that the power transformer B+ center tap is connected.

There are many ways to skin a cat, I wish there were any ways to make good electrical contacts to Aluminum..

--Chuck K7MCG


Top
 Profile  
 
 Post subject: Re: Re-stuffing aluminum can question
PostPosted: Mar Sat 01, 2014 6:15 pm 
Member

Joined: Jun Mon 24, 2013 3:00 pm
Posts: 864
Location: Champaign IL 61822
As far as electrical connection to aluminum, I have found two ways that are 100%
reliable. First is a mechanical screwed connection to the usual solderable metals
with a nicely pointed lockwasher that breaks the aluminum oxide layer.

Second, if original appearance is not critical,
is to coat with aluminum solder. You have to use good solder (Bernzomatic rod
solder is good) and a propane torch. The aluminum solder can then be attached to
with ordinary solder with an ordinary soldering iron. The aluminum solder leaves
an ugly surface. Rumor has it this solder has cadmium in it, but I don't see any
official warnings.


Top
 Profile  
 
 Post subject: Re: Re-stuffing aluminum can question
PostPosted: Mar Mon 03, 2014 9:54 pm 
Member
User avatar

Joined: Jan Mon 18, 2010 2:13 am
Posts: 15536
Location: Dayton Ohio
dtvmcdonald wrote:
Second, if original appearance is not critical,
is to coat with aluminum solder. You have to use good solder (Bernzomatic rod
solder is good) and a propane torch. The aluminum solder can then be attached to
with ordinary solder with an ordinary soldering iron. The aluminum solder leaves
an ugly surface. Rumor has it this solder has cadmium in it, but I don't see any
official warnings.


This actually works great!
Though, my first attempt, I let the torch flame sit in one spot too long and I actually melted the aluminum can slightly.
I found "Hobart" brand aluminum solder rod which is made just 20 miles away. It wets nicely to the aluminum with a small hobby butane torch, then the regular solder wets to it.
I tried breaking the connection only to distort the soft aluminum can. Fortunately the first one I did will be covered with a cardboard tube then a metal box.

Amazing! Thanks for the help!

EDIT: here is a photo I took of the solder job. First the aluminum solder, then regular solder on top. I agree, the photo isn't the best.

-Steve


Attachments:
aluminumsolder.jpg
aluminumsolder.jpg [ 70.88 KiB | Viewed 1471 times ]

_________________
Radio Interests
-Zenith
-Sparton
-Pre-War FM
Consoles and floor models, the bigger, the better!
Top
 Profile  
 
Post New Topic Post Reply  [ 14 posts ]  Moderators: Marcc, Norm Leal

All times are UTC [ DST ]


Who is online

Users browsing this forum: alabarre06, Chas, dberman51, Google Adsense [Bot], Kryptosmaster, Leigh and 12 guests



Search for:
Jump to:  






















Privacy Policy :: Powered by phpBB