Hi all,

I have just acquired this lovely old set from a friend of a friend, who wanted it to go to a good home, it formerly belonged to his father. I gave him a carton of beer as a token of appreciation.

It has no discernible brand on it, it is made of metal and has a separate speaker, which although very dirty and dusty, like the radio, seems to all be complete, the radio has 7 valves, I'm guessing it is from the 1920's. The power plug is very unusual, perhaps American? Therefore I'm guessing if and when I decide to power it up I should use 110v, for this purpose I've already bought a step down transformer for $19.99 on ebay, which should arrive in the next few days hopefully. However before I power it up I'll be thoroughly cleaning it and inspecting the internal wiring and components, replacing all caps.

I've never had 1920's radio before so any tips, pointers etc, much appreciated, as I really want to get this darling baby working! If it looks at all familiar to anybody, or if anybody knows how to Identify it, I would love to hear from you, hopefully as I go over it I'll find clues and will post updates thus.
Cheers.

No offence but I can't understand why you would just want to replace all caps in everything you find.
This approach can cause more problems and changes the whole integrity of the radio, as a collectable thing.
Not all caps give problems.
Logical restoration and repair, then maybe preventative measures to those components that are known to be unreliable.
JJ

Different people have different interpretations of what "all caps" defines. To some it'll be the literal meaning of the phrase but for others it means the electrolytic and paper condensers only.

I would agree with the latter being a good policy, especially with the electrolytics. When they dry out they go bang and sometimes they make a mess. When they develop internal shorts they overload other components.

Whilst it is good to keep radios as original as possible it has to be accepted that if one wants to run a vintage radio every day then it needs to be in good electrical condition. If radios are to be kept as found and used for display only, and I don't have a problem with that, then they shouldn't be used and as an added precaution the power cord should be cut off.

I mean electrolytic's and paper ones, because I have now experienced the damage caused by not replacing them! I would consider re-stuffing old ones that look good, with modern bits to preserve integrity, but my main aim is to keep my radio's alive and healthy! I also now check and replace resistors. Old caps thet are visible I leave in place, just remove them from the live circuit,

Regarding re-capping: I would think hard about that in relation to a radio of that vintage, where cosmetics are important.

Regarding: I've already bought a step down transformer for $19.99 on ebay

Is that an AC set, or DC? Does it have a mains transformer?

Assuming for moment it's AC, what are the specs of that eBay transformer (voltage and VA)?

Bear in mind that back in the day American mains was 110 volts, not the 125 volts that is more common these days, and also that the valve filaments (if still functional) may draw significant current.

Yes GTC I will think hard and ask advice before cutting anything out, I think if I replace any components I'll be putting new innards inside old casings, however no innards as such are visible, it must be all inside the chassis. I won't be needing the transformer for this as when I turned it over I discovered a sticker telling me exactly what it is! (I've only just brought it home from Adelaide this evening!)
It is a"
RCA Radiola 33 Model AR-784-B Range 550-1400 Kilocycles N.P.44363 (I think that's the serial no.?) Radio Corporation Of America. 200-250volts, plus a myriad patent numbers... I googled the above model and apparently it's from 1929. Wow!!! It's in great condition for restoration, the bottom is wooden, sides and top metal.
Thank you for your suggestions and input, definitely will not be offended, I want to do right by this old girl.
Cheers!

I'm jealous!

A TRF radio with a regen control.

Ancient valves types UX226 UX226 UX226 UY227 UX226 UX171A UX280, which translates to 27, 71A, 80, and 4x 26. Not quite old enough to have 01A types.

With a radio that old check absolutely everything... every transformer, capacitor and resistor, even every wire.

You certainly don't want to blow it up in some accident.

This radio looks like an export model for the Australian/NZ market. The US AR-784 is a 110 V AC model. The "B" suffix probably indicates a export model for countries with higher mains voltages.

Before you do anything to this radio you must first ascertain what kind of supply it requires. Most of South Australia's AC supply was 200v & there were a lot town DC supplies as well.

Here are some advertisements from The Mail (Adelaide).

http://trove.nla.gov.au/newspaper/article/58622395/5297131
http://trove.nla.gov.au/newspaper/article/58617218/5297351
http://trove.nla.gov.au/newspaper/article/73755990/7282176

Hi Jamie Lee,

I also have this model. It is quite similar to the other RCA sets of the time - e.g. model 18 (which is very common in Aus). You will find many articles online about recapping. One of the large 'boxes' on the right hand side will have all the electrolytic capacitors. It will be filled with 'tar' and can be heated in an oven (when the wife is out!) and will come out in a bundle, probably with a little encouragement from your screwdriver. AWA made similar cans (e.g. model 34 etc). I've rebuilt many over the years. Make sure you use the correct electro types. I usually mount them on a tag board inside the can. Also, make sure you well lubricate the tunning capacitor bearing - these tend to seize over time. I've occasionally had to disassemble and slightly enlarge the bearing hole - these are made of 'muck metal' and swell over time. All the best with your repairs.
Robert

Thank you Robert, when I get to it I'll need to work out which box holds the electro's and I'll need to find a schematic, to figure out what the actual values are, shouldn't be too hard as the model seems to have been very popular and there seems to be much information about them. Looking good, this is going to be a really cool project! Cheers.