resuscitating 60+ year old radio - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
Thread Tools Search this Thread
Old 23rd March 2004, 06:12 PM   #1
diyAudio Member
Join Date: Jan 2002
Location: Puget Sound
Default resuscitating 60+ year old radio

I bought this at a garage sale for $30. The patent numbers on the back make it no older than 1938. It would be neat to have it operational but I think it's well worth that price just as a testament to the incredible work people did by hand back then.

The power cord insulation is rotting so that is a no brainer.

There is a pile of dark wax under the power transformer that I have been told indicates that the transformer was overheated and should be checked for shorts. - Do I need to desolder the secondaries to check this?

How should apply power? Variac? Someone mentioned a light bulb in series. Does this have similar affect as a variac?

  Reply With Quote
Old 23rd March 2004, 06:47 PM   #2
adamamp is offline adamamp  Canada
diyAudio Member
Join Date: Mar 2004
Location: East of Eden
A low wattage light bulb in series with primary can be used to check for a short in the power transformer if all secondaries are taped off. There should be very little glow from the bulb, a bright glow indicates a short. A slow charge by either a Variac or series resistance with the primary is a good call on any equipment that has sat for a while. Also note that ALL the wiring inside should carefully be checked for breakdown of insulation and replaced as needed before any attempt to fire it up. Good luck and be safe
  Reply With Quote
Old 23rd March 2004, 06:56 PM   #3
Thoru is offline Thoru  Netherlands
diyAudio Member
Join Date: Jan 2004
Location: Zaltbommel

There are probably some elco's in there that need to be reformed. There's plenty of information on the web about that. Using a variac is a possibility, beter get them out there and reform them one by one.
Checking for a short is probably possible with a volt-measuring device (don't know the english word). Just apply it to one main and one secundary and check all possibilities.
Don't know how tubes behave after such a time...

Remco Poelstra
  Reply With Quote
Old 23rd March 2004, 07:09 PM   #4
Colt45 is offline Colt45  Serbia
diyAudio Member
Join Date: Feb 2002
Location: Canada
Send a message via ICQ to Colt45
Replace all the wax-paper caps (most of them look like they are of this type)

Check to see if the resistors are say.. within 25% of spec.

check no tubes are shorted,

put a fuse on the primary and plug it in!
oh yeah, reform or replace the 'lytic caps as well.
  Reply With Quote
Old 23rd March 2004, 07:50 PM   #5
diyAudio Member
Join Date: Jan 2002
Location: Puget Sound
Reforming. That's the word I was looking for. Thanks.

What's the worst that could happen if, assuming no shorts, I just plug it in?
  Reply With Quote
Old 23rd March 2004, 07:54 PM   #6
Thoru is offline Thoru  Netherlands
diyAudio Member
Join Date: Jan 2004
Location: Zaltbommel
I think the worst is that it catches fire because an elco or something 'explodes'. I don't think it will give a big bang, but you asked for the worst. It will probably just get messy.
I don't have experience with those wax-paper caps colt45 mentions, but they sound like they burn wel .

Remco Poelstra
  Reply With Quote
Old 23rd March 2004, 08:30 PM   #7
diyAudio Member
Join Date: Feb 2003
Location: Birmingham, UK
At least it looks like a standard superhet with an energised speaker - there shouldn't be any unusual or 'patent' circuitry which could be difficult to follow.

I have had a set where the rectifier had an internal short causing the mains tranny to overheat and start a fire - on the outside the cabinet looked fine, but inside half the circuitry, the mains tranny and the speaker had gone to meet their maker...
  Reply With Quote
Old 23rd March 2004, 08:53 PM   #8
NealG is offline NealG  United Kingdom
diyAudio Member
Join Date: Dec 2003
Location: .
Get your self over to

Lot's of good advice for reviving an old radio, there's a Forum also to help with questions.........
  Reply With Quote
Old 23rd March 2004, 09:54 PM   #9
diyAudio Member
Join Date: Jan 2004
Location: nowhere
I wouldn't be surprised if that insuation has been eaten away by cockeroaches or vermin in general, you're taking a pretty nice risk also by simply firing it up with that amount of heat damage and age thrown in too...

That aerovox capacitor looks brand new don't it? ;P

Amazing how deceiving age can be, take a look underneath the top-end of the Aerovox capacitor near the post, looks like it has splurted all it's wax and guts over the top of the radio while it was still molten hot!

Also those pure white-grey ones have a plastic tube if I remember , just above the capacitor in question. I have some here that look brand apsolutley new and meh they're gone!

Also a note on replacing so many things, TAKE IT SLOW! really damn slow, make sure you take a few pictures as to how it all looks, and follow them to the T, put it all back in the way it was supposed to or you'll find the AM receiving or Amplifier section has some flaw or huge hum or buzz/noise from somewhere where you've moved a capacitor 5 cm from it's original position.

Theres no need to rush things, you have a Transistor radio around somewhere? listen to that and ward off the temptation of powering it up early in the process of replacing :P

It's waited 50+ years, it can wait a few more weeks...
  Reply With Quote
Old 24th March 2004, 05:25 AM   #10
SHiFTY is offline SHiFTY  New Zealand
diyAudio Member
SHiFTY's Avatar
Join Date: Jul 2002
Location: New Zealand
If I were you, I would plug it in ever so briefly to check that it actually works (ie 10 seconds max, see if you can get sound or even better a station!) Be ready to switch the thing off if it does go bang.

Then if it does go, replace all capacitors in the thing. Replace all resistors that have drifted outside their values. ( high values like 100k seem to drift the most)

With that burned looking power tranny, I am not so confident... it may be fubared
  Reply With Quote


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
year old stylus Bama Slamma Analogue Source 1 20th March 2007 02:56 PM
happy new year anyway karma Everything Else 0 1st January 2006 05:45 AM
Resuscitating Gainclone parts group buy Andypairo Group Buys 50 14th January 2005 05:52 AM
Who's Going to CES this Year? (Las Vegas) Lusso5 Everything Else 8 26th July 2004 01:04 PM
Best New Year Yonnat Pass Labs 0 1st January 2004 11:02 AM

New To Site? Need Help?

All times are GMT. The time now is 10:49 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2