#1
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Gutting Sprague cans
I'm experimenting with a method of re-stuffing cans that doesn't mangle the crimp edge (much) and hopefully will make maintenance easy. Anyway, once I got the grounding rings and wafers out and removed some black material that came out in pieces, I ran into a really hard, black layer that I can't even melt, at least not without extreme heat. Am I going to have to heat them with a blowtorch or drill them, or is there some kind of trick to it?
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#2
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How thick was the wafer? they are usually are as thick as the bottom bump in the side and have a black rubber sheet in them to act as a seal. Once you get the wafer and terminals out you should see the bottom of the plate/dielectric roll (and possibly tar). If the roll ain't loose I use a cork screw to remove it.
I gave up trying to un-wire and un-crimp the bottoms a good while ago....I kept getting bad cuts on my hands doing the un-crimp plus all the un-wiring/rewiring is tedious. What I do is on cans that have a cardboard sleeve is pull off the sleeve, cut the can off ~1/2" up, drill ~5 VERY small holes through the wafer, for the leads, install new caps and reinstall the cardboard sleeve(can top optional). Cans without cardboard I like to use metal foil duct tape to rejoin the can top. Under chassis cans I don't bother with the tops.
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Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
#3
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Yup it must be tar, it's as tough as nails. The wafer is the same thickness you mentioned, and there was a layer of plastic film between the phenolic material and the decayed rubber.
Aw, screw it... I'll probably just mock up new cans from stainless steel pipe and end caps. I hadn't thought of that before. My goal is a high-grade restomod; I don't feel a need to make things look totally original. Last edited by Jon A.; 03-17-2017 at 12:01 PM. |
#4
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I've been wondering if one could make an un-crimping tool, if you will. Basically like a can opener, except intead of cutting, it would gradually straighten out the crimped edge. Of course, that's slightly complicated by the fact that the crimped edge has legs protruding from it.
And then you'd need another tool to recrimp it. |
#5
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Do you have a Dremel tool? One of the cutter bits should get through the rubber. The aluminum cans are soft and easily damaged.
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Audiokarma |
#6
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No Dremel tool, but there have been many times I could have used one. I've had a Dremel 219 speed control box for ages; it would be nice to find a Dremel tool it is meant for.
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#7
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I hold one of the legs with Pliers and heat the can over the stove, it does have to get pretty hot, and you need a Potholder or Gloves to hold it but eventually it will loosen enough for the guts to slide out.
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#8
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I tried something similar: I put them upright on one of the burners on top of an extra foil burner liner. They didn't smoke much but it was enough to set off the smoke detector which is hard-wired to the building, argh. It's tricky to even make toast the way I like it because of that thing.
Come to think of it they might not smoke if I use your method, I'll have to give it a go. Last edited by Jon A.; 03-18-2017 at 01:16 AM. |
#9
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Years ago, there was a Geocities website a Ham in Texas put up showing how he re-stuffed can caps. From the pictures, he appeared to be elderly, so no surprise that with the demise of Geocities, the website disappeared.
http://www.geocities.com/siliconvall...stom/index.htm <- from my 1998(ish) Netscape (4.0) bookmarks. He used a lathe and/or a larger tubing cutter (like the ones for larger diameter copper pipe) to cut the can off as close to the base as possible. From his pix, the cut was about 3/4"-1" up from the bottom (mounting surface). A sharp twist then separated the two halves, and after cleaning up the base, the upper part was chucked in a lathe and bored out. The caps were installed on the base, and he slipped the cover back on using silicone rubber and a jig to support it while it cured. He then slipped an aluminum sleeve over the old cap, concealing the joint, and giving him a blank slate upon which he put a label. I wonder how Hayseed Hamfest manufactures his - over on ARF (and in a thread on AK) the question was somewhat answered that his caps are NOS can caps that he emptied and populated with miniature electrolytics, and then placed a a deep-drawn aluminum or plated brass tube over the guts with a paper sleeve if needed.
__________________
Brian USN RET (Avionics / Cal) CET- Consumer Repair and Avionics ('88) "Capacitor Cosmetologist since '79" When fuses go to work, they quit! |
#10
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Tip on capacitor cleaning out: the black tar is easily dissolved in toluene or xylene.
In the paint section of big-box home stores its called "xylol". This is good for removing the last bits of it. |
Audiokarma |
#11
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Quote:
__________________
Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
#12
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Naw, I checked first. They don't even have my old Geocities site - it was a huge (100MB!!) datasheet compilation - mostly obsolete Motorola stuff. Back then, the only datasheet sites were pay-as-you-go, so I built my own. I had a whopping.......172 visits in 2 years
That reminds me - I have a buddy that had his business website on AOL neighborhood, or whatever it was called. When they killed that, he and I spent an evening recreating his single page site with FrontPage. 12 images, none bigger than 320x400, and a pageload speed of 1.3 seconds@56K. Amazing - his business grosses high 6-figures, and he still has a one page website....
__________________
Brian USN RET (Avionics / Cal) CET- Consumer Repair and Avionics ('88) "Capacitor Cosmetologist since '79" When fuses go to work, they quit! |
#13
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Quote:
By the way I've seen those Hayseed Hamfest caps, I really like the look of those. |
#14
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Anyway, I still do just fine with this site and others like it left that aren't laden with huge pictures or anything streaming. Definitely miss out on Youtube and such. I can do all that on a laptop I keep, but I have to go to a WiFi provider. On the upside, my computer related costs have definitely been minimal.
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"Face piles of trials with smiles, for it riles them to believe that you perceive the web they weave, and keep on thinking free" |
#15
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Quote:
Anyway, I finally got the guts out of the cans. I finally realized the hard layer I hit wasn't tar at all, it was another phenolic wafer covered in black goo from the decayed rubber. The only cans I had taken apart before were smaller single-section units from late 70s/early 80s RCAs. These were a lot harder to gut even after I realized what I was doing wrong. They didn't smoke while being heated over the stove, but their contents did upon removal so I got them out of range of the smoke detector in a hurry. Now to reverse-engineer a way to re-assemble them so they can be taken apart easily but look almost completely original; I have a couple of ideas. It's probably my OCD talking but I need to be able to check on the new caps. You never know, they could get blown by a power surge or who knows what. Why not, this TV is quite scarce and needs a tremendous amount of work so I may as well hot-rod it. |
Audiokarma |
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