Welcome to Australia's only Vintage Radio and Television discussion forums. You are not logged in. Please log in below, apply for an account or retrieve your password.
Australian Vintage Radio Forums
  Home  ·  About Us  ·  Discussion Forums  ·  Glossary  ·  Outside Links  ·  Policies  ·  Services Directory  ·  Safety Warnings  ·  Tutorials

Tech Talk

Forum home - Go back to Tech talk

 Testing radios / radio transformers
« Back · 1 · Next »
 Return to top of page · Post #: 1 · Written at 11:53:53 AM on 6 February 2009.
Chirpolo's Gravatar
 Location: Sydney, NSW
 Member since 22 December 2008
 Member #: 401
 Postcount: 42

Hi - I recently had an idea where you put 24vAC on the 240vAC plug, and with that check as if it was live, but times all readings (on the meter) by ten. Would anyone suggest this, or would anyone think this would damage the valves, electrolytics, etc. Just an idea, I haven't done it yet, (Mainly because I dont own many AC models yet) Any suggestions? Thanks!

(And also, should car wax be used on bakelite?)


 
 Return to top of page · Post #: 2 · Written at 6:32:56 PM on 6 February 2009.
Brad's avatar
 Administrator
 Location: Naremburn, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 7302

For your 24/240v proposal to work you'd need to make sure your current flow was x10. This would probably destroy your radio though. Even if not I don't think it is a good idea and because I haven't tried it I can't recommend it even if I knew it was electrically safe both to the user and the receiver.

I use Kitten car cut/polish after rubbing out scratches and dings with wet-n-dry sandpaper and this brings out a reasonable shine which I finish off with a product similar to Mr Sheen. I can't think of a reason why automotive wax wouldn't do the same job. The general rule with bakelite is that if you are unsure about how something will turn out, try it on a hidden part of the cabinet first, eg: at the bottom of the inside of the cabinet.


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 3 · Written at 11:45:53 PM on 21 February 2009.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 5254

One should not attempt to test the transformer with the valves in the set. If you run the set with too low a voltage you risk poisoning the cathodes.

Removing the rectifier stops HT being generated.
The HT secondary winding will be 250 to 300 or more volts AC and near double if you get the outside. Many current Hobby meters will not handle that.

There is also the point that 24V will not give an accurate guide to the transformers condition as there is also the fact of the magnetising power needed by its iron core. The loading will be completely wrong and the results meaningless.

An Ohmeter will confirm if the windings are continuous and an insulation tester, if they are leaking to ground or each other.

When you have established that and the soundness of the wires, it can be connected to the mains, not before.

You may need outside guidance & help here, remember mains & High DC voltages are trecherous,

No mains set should be fired up until it has been established that it is safe to do so. Many of these sets were abandoned because they were faulty.

Many car waxes use Sodium Bi Carbonate as the abrasive, this can leave a white residue if the Bakilite is porous.

Regards
Marc


 
 Return to top of page · Post #: 4 · Written at 10:28:24 AM on 22 February 2009.
Chirpolo's Gravatar
 Location: Sydney, NSW
 Member since 22 December 2008
 Member #: 401
 Postcount: 42

Okay - Thanks for that


 
« Back · 1 · Next »
 You need to be a member to post comments on this forum.

Sign In

Username:
Password:
 Keep me logged in.
Do not tick box on a computer with public access.