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Getting My Feet wet. - Printable Version

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Getting My Feet wet. - Guest - 10-27-2007

I was wondering if anybody knew of some good reference books that will help me get started in repairing tube radios and some theory. I am attempting to restore a 42-PT-7. She works, but I want to rebuild her. I know that the paper caps go bad, but visually I see no signs of bulging or blistering. Keeping it original is not as important to me as to learning how to do it. I have gone through and cleaned it out with some fine paint brushes, and some compressed air. I put some dielectric grease on the tunning drum shaft, due to the fact that it was stiff. The rubber coated wires look good but since they have not been touched I know as soon as they are they will crumble. I did replace the A/C cord with a non-polarized cord so thats safe. The one thing that I know I need to replace is the volume control. More times than not when I turn the radio on, the volume swells and can not be adjusted. I would assume that this would be the problem? And also when I turn the set on the dial light is really bright..then dims down a bit comes back alive but does not get as bright when it is first turned on. Any idears on that one? I am handy with a soldering gun, and running wires, and trouble shooting. I''m sure that I can use some of my skills as an electrician, and apply them to this. The tools I have, DVOM, Soldering guns/pencils. tons of pliers, (some blown apart LOL) and I am getting a tube tester Eisco 625 on Monday. Thank you for your time. Rich

- wonderwrench - 10-28-2007

Here is some good free info.
http://www.antiqueradios.com/archive.shtml
If it were me I'd stop using the radio until its recapped and gone through, tubes tested replaced etc. Most if not all problems will most likely be fixed.

- Texasrocker - 11-01-2007

Hello Loco!! Welcome to the vintage-radio restoration hobby!! There are plenty of good folks here to answer your questions that has been restoring vintage tube type radios for many yrs! Since your vintage radio is working, that is good!! That means all the tubes are still working. Before you turn it back on, replace all the old paper-caps one-by-one. If you examine them closely, you will notice they are different sizes. If they have a old dirty "wax" covering on them, you can go thru the underchassis and identify them on a one by one basis and replace them with modern type capacitors. Just "scrape" the old wax back with your fingernail on each orig individual cap under chassis, and it will be marked somewhere (as you carefully spin it around) with the mfds & voltage ratings. The orig filter cap cans are always mounted on top of the chassis by the tubes. The metal cylindrical can should have values stamped in the metal housing and corresponding leads from the filter can can be identified under chassis by close inspection of the symbols located by each wire feeding out of the orig filter cap. The filter caps need to be replaced immediately in any vintage radio!! These caps have a + side and - side, and polarity of these are important. All the other "under chassis" wax style caps (bypass caps) can be replaced easily one by one by simply cutting the old leads and installing a new "orange drop" of same value in place of the old one. Also, it is "normal" for your dial-lamp to come on brighter at initial power-up from the on-off switch, and them "dim" as all tube-filaments start drawing current from cold start-up! All ac/dc type chassis do that as in design. New caps can be attained from many sources. I personally like doing business with Dave at (http://www.justradios.com) for capacitors. Great folks, fair prices, and fast shipping!! For replacement vintage on off/ volume controls you can check Antique Electronic Supply, (http://www.tubesandmore.com) and see if they have the proper-value control for your retro-fit. Sometimes, you have to do a "volume control shaft modification" to be sucessfull, but thats where a good handy 1/4 inch shaft coupler, and hacksaw comes in handy! Best of luck on your restoration!! Icon_wink Randal

- jsaxe - 12-21-2007

Schematic for your set is here:

http://www.nostalgiaair.org/Resources/568/M0013568.htm

Don't work on your radio with wet feet, Loco.