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Them darn metal can capacitors

Discussion in 'Home Brew' started by Radio Tech, Oct 9, 2009.

  1. Radio Tech

    Radio Tech Radio Operator

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    Dont you hate it when you get one of those metal can capacitors go out in your nice boat anchor rig? Some are next to imposible to find or the replacement is old new stock that has or may be dried out.
    Or you can put new axel leads under neath but that takes away from the original loom.

    Here is one remedy I have been doing for a few years.

    In this case a tram D201A has a bad 10uf x 4 at 450volt capacitor. 2 of the 4 legs were shorted.



    The fix.
    Order some 10uf at 450 from mouser. Part number 871-B43827A106M000.
    These caps are very small in diameter.

    Put on some rubber gloves.
    Take the old metal capacitor and with a fine blade hack saw cut it at the bas where it goes from large to small. Remove all the insides and the thick cardborad and tar at the bottom. With a dremel clean out any aluminum around the edge of the base. When done correctly the top half will slide into the bottom have. Makes it look like it was never cut.

    [​IMG]

    Next align the 4 capacitors together with the negative sides faceing one another. Solder the grounds and cut off leads leaving about 1/8 of an inch.

    [​IMG]

    You can see how the capacitors fit right inside.

    [​IMG]

    Solder the positive sides of each capacitor to the bottom legs. They will be a little loose but that is ok for now.

    [​IMG]

    For the ground this is where you need to drill a small hole next to one of the mounting legs on the base. The case is aluminum but the n\mounting legs are tin. Insert a piece of hook up wire in the hole and solder to base of leg. put heat shrink around the wire and connect ot ground on capacitors.
    After this is done grab the hot glue gun abd glue all the legs down and filling the void between the capacitors and base. Do not fill the entire base because the cover will need to slip inside.

    [​IMG]

    What I did next was take the cover and lay on a piece of wood. I made dimples from the inside out 1/16 for the edge every 1/ inch around. This makes for a press fit and holds togeter pretty good.

    Now re-install your new old looking capacitor back in and injoy have a new part that looks like it is original.

    [​IMG]
     

  2. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    As soon as I read this part "Dont you hate it when you get one of those metal can capacitors go out in your nice boat anchor rig? Some are next to imposible to find or the replacement is old new stock that has or may be dried out." I thought about your idea. I did that once,thankfully it was just the one time, and it worked out very well.I was cringing all the time I was putting it back together and turning the power on for the first time after. GREAT STUFF!
     
  3. Radio Tech

    Radio Tech Radio Operator

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    I know what you mean. It is a pain when that happens.
    I really particular about replacing parts in a old rig. I lke everything to look original. One thing I can not stand is when someone drilles a hole to mount a switch or something. Drives me up the wall.

    Gald that one you did worked out for you.

    Thanks


    BTW
    Sorry about the picture quality. Wife took the good camara with her today so I am using the "ghost hunting" camara with night shot. Very had to focus in a bright setting.
     
  4. Moleculo

    Moleculo Administrator
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    Nice idea. What a pain to do, but if you're trying to restore an old rig, it sure pays to have it look nice. I bet your customers love it when you do stuff like this.
     
  5. Radio Tech

    Radio Tech Radio Operator

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    The guy that owns the rig for this cap came over while I was building this one. He sat there and watched me do it. When I was finished he said someone is going to be happy.

    I said, "You YOU will be".

    He was amazed.
    :)
     
  6. sKiZo

    sKiZo Member

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    Drat ... I get away from the hobby for 30 years, and wouldn't you know it, I have to make my own dang parts now ...

    FYI - I couldn't get a match on your Mouser number. Then again, I needed different values anyway. <G>

    Would you believe I stumbled in here by gooooogling "Them darn metal can capacitors"? Something like that anyway. I suppose I could maybe find some "new" ones, but as you mentioned, NOS is a time bomb ticking when it comes to electrolytics.

    I'm recapping my trusty old Robyn T240D ... AKA Yellowbird. Glad I was sitting down when I saw what Mouser wanted for the .1 600wv and .047 600wv film axials. EIGHT BUCKS EACH?? Holy Crap, Batman!! Did some digging and found them much cheaper - well - less expensive, at a place that sells Fender guitar amps and parts. Here's a link:

    Amplifier Parts - Specialty Guitars

    Scored a couple 12AX7 tubes while I was there. Maybe worth bookmarking.

    Anyway ... thanx and a tip o'the hat for the DIY info. Not being a purist, what I may end up doing is reusing the original base plate and replacing the top with an old colored pill bottle or some such. Put a couple fuse lamps innit and hook those up to the mod light circuit so the whole interior of the radio flashes on and off as I spout my pearls of wisdom ... yeah ... that's the ticket!
     
    #6 sKiZo, Feb 7, 2010
    Last edited: Feb 7, 2010
  7. packrat

    packrat Active Member

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    I have seen that repair / mod years ago. It works, but it is a lot of work when the parts are readily available, and are not too expensive, when you factor in repair time.
     
  8. sKiZo

    sKiZo Member

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    Can't say that I've noticed them being "readily available". Plan B for me would have been stripping down an old parts radio for one, but that's another potential can of worms. Even if you find one that tests good, how long's it gonna last? I do have an old Lafayette Comstat junker with a good Mallory can in it. Still debating whether to slap that one in and see what happens.

    Lucky for me, it'll be a DIY project (at least till I blow something up and go wimpering to the shop) so time isn't a factor. I do plan to call around a bit first to see what's available, but it's nice to know there's other options.

    Besides ... I LIKE to tear stuff up! This is right up my alley.
     
  9. Radio Tech

    Radio Tech Radio Operator

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    I bought a few metal can caps on line several times. Most of them did not last long after being installed. Maybe just my luck.
    Most of the time when I am caught up in the shop I spend a few hours rebuilding caps like the one above. I cut 10 at a time, clean them out, and then install the new capacitors. Usually done in steps on different days. So really when I look at it, the time it takes to do a few is not really that bad. After you do it several times it only takes under 30 minutes.
     
  10. packrat

    packrat Active Member

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  11. mechanic

    mechanic Well-Known Member

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    (y)
    This is a fix done for audiophile fanatics with their tube amps, the repair you have is a different twist and will be a way to get my old EICO HF-20s back to life!
    (y)

    Thanks! mechanic
     
  12. Radio Tech

    Radio Tech Radio Operator

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    Good Deal!
     

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