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My 70 has 2 Sprague caps which are mounted with a nut under the chassis.
Previously I had no problem neither with Mershons (having the caps atop), nor with Sprague ones mounted with a band where the seam would be hidden,
but this time it not the case.Any ideas? Thanks.
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Well, if you are asking a question such as this one, it is natural of us to expect a picture, otherwise what are we to comment on?
Meantime, if it has a cap on top with a groove, I cut along the groove and then glue the cap back. Looks decent.
(This post was last modified: 06-26-2014, 08:31 PM by morzh.)
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Well, expecting the answer from the esteem Forum Expert,I would not dare to bother the one with such a common, run of the mill capacitor photogragh. As I recall, way back there had been a similar inquiry of mine (nickel plated copper Sprague caps), and at that time I had impression that these particular capacitors are very familiar to the latter, hence no picture needed.
Meantime,as you well aware by now, I am trying to stay as close as possible to the original issue, so cutting and gluing, having the seam on the plain site, is unacceptable, but thanks for the advice all the same.
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I think on the Sprague caps you will have to uncrimp it at the base and pull the guts out, rebuild it, and then stuff all back in and redo the crimp as best you can. I think Bob Andersen shows this on his 15DX video's.
Gregb
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Thanks, Gregb,
That's what I also thought. I might have to make special roller tool to bring the metal back. Hope it is already annealed.
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I was lucky, mine had the nice copper Mershon's and the cap on top comes off and your good to go.
Gregb
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If you can't find a cap to remove you could cut the capacitor can with a pipe cutter like you would use for plumbing., and then see if you can find a plumbing part to couple the two halves together from the inside. I have one that I bought that will fit up to a 2'' pipe, the cutting wheel is mounted on the end of a square shaft.
Regards
Arran
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I know this will probably not make you happy, but if it were my radio I would be looking for the copper or nickel plated Mershons, making the question moot. Which I have done too may times to count.
The nickel Mershons are soldered back together from a cut in the groove, filed slightly if needed and lightly wire brushed. It is hard to tell they were apart. Just finished the 2 on my 15X. P.S. even though the groove is hidden beneath the clamp mount, I still know it is there and it makes me sleep better at night knowing that in 100 years someone will cut them apart unnecessarily (I also use 630 volt film caps as replacements) and go WHAT THE -----! 
"I just might turn into smoke, but I feel fine"
http://www.russoldradios.com/
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Phlogiston
What you have just described actually makes me very happy. I can do a lot of things with a solder including forming and even body work (many years back, as a hobby).
Please tell me where do you cut the groove- in the middle or at the edge?
Your caps are mounted by clamps, mine are not, so it has to look 100% correct.
Also,how high is the bakelite? If it is below the groove, I can make and solder inner short copper nipple the the either side, put both halves together and then fill with solder prior to the filing and wire brushing. Thanks.
BTW, they are nickel plated with a groove on the bottom.
(This post was last modified: 06-27-2014, 02:51 PM by fields 100.)
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I cut with a fine blade hack saw at the top of the crimp (grove). I even up the edges and lightly wire brush then use flux and an 800deg iron. Apply the solder like you were doing a weld. The color of the solder covers any exposed copper and matches the nickel nicely. If mine weren't already installed I would send a picture.
I use the 8mf caps spec. for 25hz transformer.
The Bakelite is well below this level.
"I just might turn into smoke, but I feel fine"
http://www.russoldradios.com/
(This post was last modified: 06-27-2014, 05:08 PM by Phlogiston.)
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Thanks,sounds like a good plan. I have an early 70, no AVC,originals are 6uF each, can I go 10uF for the occasional usage?
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10 uf will be just fine.
Steve
M R Radios C M Tubes
(This post was last modified: 06-28-2014, 07:52 AM by Steve Davis.)
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With the trick I mentioned, I just used hot glue to hold the two halves together, but then again this was an aluminum can and I used a PVC coupling, so soldering was NOT an option like with copper, brass, or steel. Plus it has an electrolytic cap inside which will need to be replaced at some point.
Regards
Arran
(This post was last modified: 06-27-2014, 11:05 PM by Arran.)
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Arran
With aluminum, indeed, there are not many choices. I have done the same thing as you, having PVC tubing inside, many times, but there always until now have been the clamps, so the seam could be hidden. Not this time around though.
BTW, I have somewhere the special flux and solder for the aluminum soldering but have not tried it yet. I know it is doable though.
Thanks.
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