Viewing 9 posts - 1 through 9 (of 9 total)
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  • #8070
    Claude Squire
    Forum Participant

    This is my first attempt at restoration. I read that most capacitors should be changed, so I looked at the parts list on the drawings but they are different from what is inside. Do I replace according to the drawing or what’s inside?

    #8071
    Jerry Tombari
    Forum Participant

    Hi from the SOO. I would replace in kind (same as whats there) but note the differences if the radio fails to work. Just a caution make sure that the voltage rating is the same or larger than whats on the schematic. Hope this helps.
    Luck Jerry

    #8073
    Dan Walker
    CVRS Member

    I go with the schematics when I change caps. If someone changed a few of them in the past, they may not have put in the proper values, and the radio may work , but not as it should.
    I never trust the work of someone else because I have seem the wrong ones many times, Especially where electrolytic are concerned.

    #8077
    Gary Albach
    Forum Participant

    Hi Claude and welcome. You mention restoring the radio and your question ventures into the spectrum between ‘repair’ and ‘restoration’. I’m with Dan here and prefer to go back to the values on the schematic when changing caps. Repairs can often be done with different values to get a radio going, but personally I like to restore the radio to be as close to the original design as possible. After repairs have been done by different folks over many years, the components in a radio may be quite different than in the schematic, and occasionally even in different places!
    Gary

    #8082
    Claude Squire
    Forum Participant

    I was thinking that I’ll get a new cap with the value on the drawings and mount it inside the old one, when the old one is physically larger. In 50 years the next collector can see what was there and what I did. Anyone ever do this before?

    #8132
    phil
    Forum Participant

    Ive done it before and many have. If there isn’t room underneath or if you have interference from the location you might put them in the original cans. the problem may resurface more quickly than you think.
    after doing a few like that I am of the opinion that I just don’t trust most of the modern chinese made electrolytics to last for very long and maybe they are easier to check for being puffed up or leaky if they are underneath.

    with the paper caps. If you want you can put them in a double boiler with some wax and let them re-melt then push the guts out with a pencil, put your new style caps inside the paper tubes. If you want you can solder new leads on as the old ones are thicker. hide the soldered connections inside. after the paper tube is re-stuffed you can seal the ends with a bit of paper towel and then hot melt glue to close them and dunk them back through the bowl of molten wax.. then you won’t loose the labels, everythign will look like it did and because it’s under the chassis no one will even see your work. If you do a really good job someone may come along and recap it thinking it hasn’t been touched. I have even tried drilling out the black beauties on my lathe and restuffed the plastic tubes. It’s a matter of choice how far you’d like to take it.

    I think it depends on the radio. If it is something rare, or if you just like doing it that way you can. its good to take a picture and try to keep the wiring layout as sometimes if you move them about you might get some interference from other components.

    if you re-stuff the cans be aware that sometimes they are insulated from the chassis and sometimes not. look for things like washers that may insulate the can from the chassis and keep it whichever way it was. make sure you have the electrolytics wired the right way around or they will blow up. Be extra cautious of hot chassis radios. often if they are say +/_ 20 % or so that’s fine. If they have been replaced you;ll probably see evidece at the sldered joints. I’d go to the schematic if they have been changed and I’d question the schematic if they appear original. your new caps should meet or exceed the voltage rating on the new cap. with the paper caps you’ll often see values lke .5 mfd and then use .047 or something as close as you can get. more experienced restorers will sometimes know where the cap size would have an effect and if not they might not worry if it is somewhat different and use what’s at hand. some will change the cord to a polarized one and put an inline fuse under the chassis. some want the cord and plug to be old. Ive been known to buy old irons or cords from fry pans and things from thrift stores as often I get those for a couple bucks and many times if they have been stored nicely the rubber cords are still pretty safe, these appliances often also have thick wire and good insulation. you might encounter some radios with resistance line cords or “curtain burner” cords and those need special consideration.

    if you want to use cloth covered wire you can stock all the different colors and you can get reproduction old looking lamp cord. often with the rubber wired ones you will find sets where it’s all turned to peanut brittle or goo and some sets need to have all the wires replaced As you are working also notice the condition of the insulation. sometimes you can pull heat shrink over or you can get authentic “spagetti” which is the semi rigid hard tubing that slips over but doesn’t shrink. cetrtain radios like the westinghouse refrigerator one may be so crammed that you need to put them in the original space. some of the older radios have tin blocks that are filled with tar and these may actually not be electrolytics but paper caps. with the pre 1929 radios space under the chassis usually isn’t prohibitive.

    another option I have tried is to make my own cans from sheet aluminum or steal from another set if they are missing. one way to get them apart is to cut them with a dremil and a disc around near the base. if you have cans that have tar try heating the outside with a torch and see if you can get the tar that is against the tin case melted then it may drop out easily without melting all the tar. It’s probably a good idea to wear gloves and discard of the old electrolytics in a safe way. they might have hazardous products in them.

    Phil

    #8285
    Eric Strasen
    Forum Participant

    Phil makes a lot of excellent points here, especially in regards to AC/DC radios built in the days when five tubes didn’t add up to a 117-volt filament string. Radio manufacturers got around this problem with either a resistance line cord (“curtain burners”) or a ballast tube, which is basically a large voltage-dropping resistor in a metal can. While definitely safer than a resistance cord, the ballast tube ran very hot and tended to cook the finish on the portion of the cabinet above the ballast.
    Some years ago, I read about a fix for this involving the use of an AC motor capacitor to replace the ballast. Supposedly, the motor cap runs cool as a cucumber while dropping the set voltage to an acceptable level. I haven’t tried this and have lost track of the fix.
    Perhaps someone reading this can enlighten us.

    #8327
    phil
    Forum Participant

    my 1929 rogers set uses a weird item. it’s a tin can punched full of holes with a plug on it like a lamp. the chassis has the socket for it. inside the can it has a heat element and above it there is a metal heat shield. I never know if this was incorporated to keep the room warm or to stabilize the power or what. at one point I found a NIB one and I think that was for a Majestic which was a similar radio.

    I have an old tool. 1020’s or 30’s maybe ? it’s an electric jackhammer. it runs on 220 volts. in the cord it has the same sort of has heater thing. the jackammer is purely electric, it has a big elecromagnet and the power must be continually turned on and off so maybe it was to prevent electrical interference in the power grid, or something?

    #8331
    Eric Strasen
    Forum Participant

    Phil:
    Can you post a photo of this strange can? I can run it past an electronics professor friend in Georgia. If anyone can identify it, he can…
    Eric S.

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