Hi All

I have on the workbench a 1931 AWA Radiola 45E, Model C79. Its in very good condition for its age. I have been asked to do an electrical Restore only and not Fix any of the Cosmetics that don't have an effect on how the radio works...

The chassis has some general rust on top but looks ok and shouldn't be a problem. Underneath it looks like it came straight from the factory. its very clean and all the cotton covered wire is immaculate.

The issue I have is locating the Capacitors in it. Using the service manual from Kevin Chants Website:

http://www.kevinchant.com/uploads/7/1/0/8/7108231/awa-45e-circuit-diagram.pdf

I can see the Power Supply Smoothing Caps on the diagram, The text states they are inside one of the Boxes, No Problems!!!! well those boxes are potted with TAR. I cant fInd enough Wires coming from the TAR Lump in box No.2 that also houses the 2 power supply filter chokes (2 chokes on 1 core). I can count 4 of them from what I assume is the capacitors and there is definitely no Black wire here at all. I can see the choke wires and there is no connection to them in the Box from the capacitors. THis happens on a tagstrip under the chassis with the Decoupling resistors.

This also raises a Question, What Value Caps do I use. I was thinking 8μF 500V. I plan to mount them inside the box so not to look out of place.

The next thing is the "Minor" Caps. I assume they hide in the other 3 little boxes towards the front of the radio.

Any help is appreciated.

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

What can be confusing is that if the caps are going to a common ground then there is liable to be one wire for all and if a cap does not go to ground it may have two wires.

I would like to see voltages but with #80 I would no go below 500V. I will see if I have a circuit? The other issue I have considered is replacing "outside foil" caps with modern ones which are not. I have actually used grounded "shim brass": zig zaged like corrugated iron between them to duplicate the outside foil & reduce induction.

You may have to tag where the wire came from, then dismantle the can.

Hi Marc

I have not powered up the set of cause...

The Circuit as listed above is missing its voltages but a rough indication is given in the faultfinding section on the 2nd last page.

I was hoping to find 1 common wire for the PS smoothing caps (Black as indicated on the diagram) but is missing or never there by the look.

The best part is that no one has been "At it" before me!

Dan

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

Always unwise to power such a set. The filters are liable to be paper types. Shocker of a circuit, however it is not unlikely to be similar to another.

They do give 700V that is the HV secondary plate to plate AC Voltage of the #80. It looks like its back biased so there could be a burnt resistor between ground & it. It may actually connect to the grid of the OP tube via its grid leak.

- deleted -

Robbbert, I think it behoves anyone to do a "sensitive" restoration of such a valuable radio.

I'd be melting the can contents out in an oven and potting new parts in the can using hotmelt glue.

I would not be happy changing the appearance.

Hi Guys

"Robbbert" The Box is metal and there is no visible connection with the internals and the chassis. In Fact they are isolated by pitch and cardboard.

"Ian" I can hide the New Caps inside the can, Like you said I dont want to disturb the appearance of the set. Originality is king on this one. I even carefully cut the cardboard inner of the can to expose the Pitch encased Caps. All is going to be put back together with New Caps.

I had to carefully slide the contents out of the can to do all of this.... It worked without heat so far....

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

The Radiomuseum could do with some good photos of that set. I'm sure Sirwin would be happy to upload them, given permission.

I have a subscription as well. I will get Photos tonight (Send to Brad)

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

Do not forget my comment on induction between caps. I normally line those cans with insulation. If you dare to use silicon use the non acid roof & gutter type. Frowned on by some but it makes a wonderful binder & space filler. Just keep it off the wires, some of it can conduct.

If you can use the old wire fine, but do not change the colour scheme if you use new. Hopefully the caps have values on them?

Explanation of Photos

Photo 1 - Front View of Chassis. Not the correct Knobs! Valves and Cap shield Removed

Photo 2 - Rear View once Can was removed. Silver part is the Choke and the Cardboard box is the Caps in Pitch.

Photo 3 - General top View, Not much to say! I have removed the valves and placed the covers back in place.

Photo 4 - Side View of the Choke showing the "Winding" leads.

Photo 5 - Other side view showing the Carefully opened Box containing the potted Pitch Caps.

Photo 6 - Underside View of the Leads from the Caps.

Photo 7 - Overall Underside of the Chassis. Note how clean and organised it is. I haven't cleaned it in any way except to cut off power cord.

Photo 8 - I assume these hold the other signal Bypass Caps, How do I get into these????


Over to you Brad

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

Photo 1 uploaded to OP. Photos 2-8 uploaded to Post 9.

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

Thanks Brad.

Any thoughts Guys? I dont want to butcher this one....

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

Hi Flakes, that is a lovely radio and a real head scratcher as to keeping it original or restoring it completely.
The electrical side is easy and following Marcc's advice is the way to go as he does this sort of thing all the time.
A real problem is interfering with the state of the plating and paint.
There is a lot of surface rust that gives the set the 'patina' and that original look.
You cant remove the rust without a major pull down and re do the finishes in exactely the same way as original.
The temptation would be to clean the surfaces with solvents that 'fix' the rust and then maybe dust a coat of clear over that.
If I try to remove rust by any scraping, sanding that just leaves scratches that cannot be hidden by the original plating and laquer procedures.
I have seen radios fixed by 'experts' where they sand the chassis down and silver paint over the lot...yuckkk.
The only way to repaint or replate the surfaces is to strip the thing to the last wire and rivet, chemically treat the metals to stabilise the surface and to re-plate and re-laquer to as new, and to reassemble.
That is a million dollar job and to me stark raving mad but if the customer wants a 100 point resto fair enough.
I completely rebuilt a 1940's Kriesler on this web site by nut and bolting the set and chemically treating the metals but then painted in sympathetic colour paint of the 'hammertone' type to cover up rusting damage which deleted the originality of the set but I was the customer in this case and ok with that approach.
With this one, and the other guys will have a comment i'm sure, perhaps just leaving the chassis all intact and liquid CLEAN the surfaces carefully so as not to remove any original stencil or pencil marks. Any bolt on cover, box or shield be treat chemically, stripped and 'hammertone' to a brown or grey, any round alloy cans or shields SPIN them and dress them to a uniform matte appearance (NOT polish!) and carefully reassemble. All the dial pieces may just need to be cleaned. Maybe then "fix" all bare cleaned metal surface with a matte clear spray??
I think you have to treat each part of the chassis separately and apply the clean/paint/whatever as applicable without changing the appearance . I have done this "partial" clean and paint the loose parts to other sets and that looks quite nice.
Otherwise you severely leave it alone, all rusted as she is, just tuck the replacement caps into the cans bolt it all up and leave it at that?
It sounds like that is what the customer wants and he is paying the bill!
Fred.

Hi Flakes, I must say that is a lovely radio and you are right to leave it as much alone as possible. One product that I have used in similar cases that is not petroleum based that is great for stabilising rust is Lanox. It is a Lanolin spray made by Inox. I think most of the auto stores sell it.

I have found that it does a good job of stopping the rust progressing and is very gentle on paint. My approach has been to apply a generous spray and then soak up the excess with a clean rag some time afterwards, but that may not be safe as I would not want to get any on the underside of that chassis the way it looks now. As always try on a small inconspicuous area first before proceeding further.

I don't know how it works but the things I have used it on have stopped rusting without the need for further application. Maybe that's why you never see any rusty sheep

Frank.