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

 1931 AWA Radiola 45E Model C79
« Back · 1 · 2 · Next »
 Return to top of page · Post #: 16 · Written at 9:04:44 PM on 26 October 2017.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 3967

In reality some of those chasses were plated. The only real way to stop the rust would be to strip the chassis & some actually do that. The rust can get very deeply into the metal. With cars these days they are dipped & that coating resists the spread of rust if there is surface damage.

There are those who dip car bodies after market for the restorers: Not cheap but that would work on a chassis as a replacement & protectant. I have noted on the Lathe bed that the Lanolin is not as good as I thought, it might be. There are various chemical from Potassium Permanganate based ones, to things like Phosphoric Acid based. Not to be tried on radios, or without suitable protective gear etc. I did have a ladder recently that had been in an orchard for decades. Its metal was severely pitted & rusted: That I used Hydrochloric Acid (Spirits of Salts) on.

With a 1929 Lyric 70 (USA) I got landed with, (OP tube #50: Cost frightening) that had a mass of caps in a plug in can (transformer also plug in). That came out with some prompting with a heat gun, unlike a Grigsby-Grunow, where the lined can allowed easy removal. The Lyric cans were a common "Mission Brown" so got repainted along with the replacement (missing) Faraday cage I made for its first four valves (TRF).

Now you get the fun bit. None of the caps will, as discovered be attached to the can, even if they go to earth. There are colours that look the same so there is a probability that the caps on the same colours are the same value? You should have photos of all wires from that block, showing where they are attached, but you still need to identify every wire. the pastel ones are easy as you can just put black dots on them & coloured dots on the others. Some of that marker removes with circuit board cleaner.

Unless there is a better circuit the capacity may have to be referenced to physical size & measured. The capacity may read close even that the cap leaks like a sieve.

In respect of mechanisms: If there is grease involved, invariably it will dry out & sometimes weld. All of the old grease soap should be removed. Mixing grease types & brands is a no no; That can result in the soap solidifying due to different chemicals being used by different manufactures. Also Lithium & Bentone greases are incompatible.

 Return to top of page · Post #: 17 · Written at 9:39:10 PM on 26 October 2017.
GTC's avatar
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 5514

.Flakes: do you have any photos of the case?

 Return to top of page · Post #: 18 · Written at 7:31:56 AM on 27 October 2017.
STC830's Gravatar
 Location: NSW
 Member since 10 June 2010
 Member #: 681
 Postcount: 878

In terms of grease I use brake grease that I bought thirty years ago and has seen me through three cars. It is a high temperature molybdenum disulphide (moly)/teflon grease. Even on brakes only a smidgin is needed. It was very expensive and at the time I only bought it to fix a chronic brake judder on a Subaru Sports Wagon, but thirty years later I have still got it (toothpaste tube size) because little is needed and it lasts between shoe and pad changes. I'd give the brand but the printing has come off the tube, but something like it should still be available as it was bought at a local car parts and accessories shop.

This has also been used on tuning gang bearings and shafts and various other jobs where you don't want grease to dry out. Might be good for turntables since it is good for oscillating fan mechanisms.

 Return to top of page · Post #: 19 · Written at 8:23:06 AM on 27 October 2017.
Flakes's avatar
 Location: Adelaide, SA
 Member since 27 February 2010
 Member #: 630
 Postcount: 392

Hi Guys

Thanks for the tips about the grease. I have something here like that. I used in my antenna rotator, its was and still is magic stuff....

As for the chassis. I am not too sure what I am going to do. The owner is doing up the woodwork and I gave him guidance on it, but wants the look of the chassis to be exactly what it currently is. I think I will use a light oil to just rub and protect it a bit.

I just have to replace the caps as the resistors and transformers seem to check out ok.

Anyone got any tips for how to remove the 3 small under chassis cans that hold the small signal caps.


Valve radios, They just don't make them like they used to

 Return to top of page · Post #: 20 · Written at 6:57:58 PM on 22 February 2018.
Robert69's avatar
 Location: Western Victoria, VIC
 Member since 14 November 2009
 Member #: 579
 Postcount: 106

It's a bit late (I just saw this post) but a really good full restoration of one of these sets was presented in RadioWaves a few years ago. A look through the HRSA index will find it. A redrawn circuit and components values was included. If desperate I could scan and upload a copy, but it might be a moot point (e.g up and going by now?)



 Return to top of page · Post #: 21 · Written at 7:13:44 PM on 22 February 2018.
GTC's avatar
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 5514

a really good full restoration of one of these sets was presented in RadioWaves a few years ago

July 2009, page 5 (by Ray Hosking)

« Back · 1 · 2 · Next »
 You need to be a member to post comments on this forum.

Sign In

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