Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 20th May 2004, 01:54 AM   #1
diyAudio Member
 
zagisrule!'s Avatar
 
Join Date: Apr 2004
Location: Edgewood, NM
Default RCA Tube Radio...circa 1930-40

Hi guys,

I would like to restore an antique RCA shortwave receiver to working condition. I have examined it and tried to power it up resulting in the power transformer draining wax from it, accompanied by a burning odor.

So, the capacitors are all shot...most are the oil-paper type with 2 very old electrolytics that will definately not work.

The resistors might be shot...I will go through and read values and get replacements.

Do tubes go bad? The radio worked just a few years ago, I assume the tubes would stay good?

Should I replace all the components with the point-to-point method used in the original consruction or find a schematic and build a PCB to replace the point-to-point mess? I assume I have a bettter chance of getting it running again if I just replace each part one at a time, swap an old part for a new one, one at a time until all new parts and wires are in there.

Does anyone have any experience in this? It is a large, stand-alone cabinet. There are only a couple tubes and one small power transformer that says:

117 V
75W
B 95-756

There are 9 wires going into it, with 2 of them the 120VAC input for power. I can get all the other parts by reading their codes, but this transformer is completly foreign to me.

Are there any websites with info on this kind of thing?




Any help would be greatly appreciated!



-Matt
  Reply With Quote
Old 24th May 2004, 12:04 AM   #2
Jeffy74 is offline Jeffy74  Canada
diyAudio Member
 
Join Date: Jan 2004
Location: Near Montreal, Quebec
Hi,

When I restore an old radio, I replace ALL papers and electrolytics capacitors, it's more safe. If you have a metal can on a chassis, only cut wires and put new caps under chassis (new ones are smaller, so easy to place). Do not remove can! You will preserve originality of radio with this method. Do not replace the mica caps with colors dots on it (theses caps are square or rectangle and brown, they are always good. Habitually resistors are OK and anyway, tolerance of resistors and caps is about +-20%!! You can put anything and the radio will still work... I always put a fuse between 120V ac wire and on/off switch (less than 1A, you can calculate with AC voltage and power consumption on plate in back of radio), it's safe to put one, because theses radios are really old and we never know when a trans or a rectifier tube will fail. Check also if primary and secondary of all trans are open or not with a ohm meter.

If you have any questions, just ask.

Jean-Francois
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
L. Tatro farm radios from 1930's. rhtatro Tubes / Valves 3 16th October 2010 04:58 PM
Driver from 1930 RCA radio, dead mag lochness Multi-Way 14 4th July 2008 06:47 PM
Help - tube radio JDeV Tubes / Valves 49 19th October 2006 08:18 PM
Tube Radio Kit cuallito Tubes / Valves 11 29th May 2004 10:59 AM
Another tube radio Magnetmaz Tubes / Valves 7 11th March 2003 06:01 PM


New To Site? Need Help?

All times are GMT. The time now is 04:02 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2