Bush AC41-My First Restoration

[Flecktarnfisher]

Evening all,
I've always loved old time radio shows and rock 'n roll. Whilst at the Bill Targett Rally last weekend with our car, I spotted a vintage radio looking a tad tatty amongst engine parts for sale. I couldn't leave the lovely thing where it was so...
It ended up in our car! I was told by the guy I bought it from that it lit up but none of the dials worked properly; just white noise apparently (but I wasn't that brave to plug it in when I got it home). My main reason of buying it was to restore the case and build a small portable mp3/bluetooth amplifier within the case to take with us on car shows to play music through but I don't want to scrap the innards in case they work but they are so filthy and were slightly damp when I took the back off yesterday. So what does everyone recommend I do?

I've never worked on high voltages or valves/amps in my life. I know enough electronics to pass me with my mechanical skills but thats really only engine leads.
Many thanks in advance,
Lloyd

['LIVEWIRE?']

First of all be aware that many vintage radios have a 'live' chassis -i.e. no mains transformer is used, one side of the mains, which should be the Neutral is connected to the radio metalwork. Secondly, do not plug it in to 'see if it works!' As has often been mentioned on the forum, a few cheap components will almost certainly be faulty. These, if not replaced, will almost certainly cause other parts such as the output transformer to fail. Forum members living in your area may be willing to help you clean, repair & restore the radio, which, if it has 'gram' sockets could then have external device(s) such as MP3 players, etc., connected to it. The external audio source would then play via the original amplifier and speaker.

[ThePillenwerfer]

An AC41 is a good set to start with as it doesn't have a live chassis. You still need to be careful in how you work on it but the risks are lower.

It also has Gram sockets that you'll be able to use for your Bluetooth/MP3 device.

The first thing you need to get is the circuit data, which can be found via the link in the top right-hand corner, I'd recommend you get the manufacturer's version.

For general information you can do no better than study this site: https://www.vintage-radio.com/

The fact that somebody has tried it and says it produces 'white noise' at least shows there's life in the beast. As Livewire has said, it will need some attention before it's safe to use. In this context I refer to the safety of the set itself rather than you.

When you've had a look ask anything you feel the need to.

Good luck and enjoy yourself.

[David G4EBT]

The AC41 is a nice radio - one of my favourites. It has a large speaker and a tone control and they sound really nice. As Joe says, you need the service data and as with all Bush radios, their own data (in this case, ten pages) is far better than the two-page 'Trader Sheet'. If you do set about restoring it, make sure that if you refer to any component numbers, you are referring to those on the maker's service data - not the Trader Sheet as the numbers always differ.

You're quite lucky that it's the AC41 - not the DAC41 live chassis set as it will be safer to work on. (The service data covers both).

If you don't wish to do a full restoration, there are a few components which you really ought to change. In particular, the audio coupling capacitor 'C20' whose job it is to allow signals to pass to the output valve, while blocking DC from getting to the valve. If that capacitor 'leaks' in the electrical sense, it may harm the valve and output transformer.

Other capacitors which would as a minimum be on my list to change, would be C21, C25 C22, and if you intend to use the Gram ('pickup') socket, C6.

How much you wish to do to the set is entirely up to you - I wouldn't presume to tell others what they should do with their own property. Some just want to 'mend it/do it up a bit/get it going' but personally, I never touch a set unless I intend to restore it and the approach I adopt is safety first, functionality second, originality last. Inevitably on sets such as this one - released in May 1954, so now more than sixty years old, some of the wiring will have deteriorated, some of the resistors will have gone out of tolerance and the mains flex may be suspect, is only a twin flex (unless someone has changed it), and will most likely not be anchored - possibly just tied in a knot to restrain it. Acceptable in the 1950s - not today.

I've restored two of these - one for myself, one for my son. I always make a simple 'cradle' to mound the set with the chassis inverted. Balancing a chassis upside down can lead to damage and make it difficult to take voltage readings. I've attached a few pics of the last one I restored in 2015. The first pic shows the simple 'cradle' - four brackets made from flat iron strip on a pice of scrap ply. Second the inverted chassi ready to be worked on. , third pic a close up pic of some of the work, fourth pic is the restored chassis, and the last pic is of the 'scalps' taken. Three resistors, four waxy paper capacitors, the cathode bypass electrolytic capacitor, and the twin unit reservoir/smoothing capacitor (to alleviate hum). Also, several defective pieces of wire.

If you look at the bottom L.H. corner of pic 4, you'll see that I replaced the old twin flex with new three core flex, anchored to the chassis with a 'P' clip, and earthed to the chassis.

As I said earlier, how much or how little you do at it is entirely a matter for you, but with any electrical appliance more than six decades old, it's unrealistic to expect it to work reliably and safely without some fairly extensive work. That said, though I wasn't counting, I doubt it took more than eight to ten hours, and for me, it was no chore as it's my hobby.

Hope that helps a bit.

Good luck with the set, whatever approach you adopt.

[Nickthedentist]

Great advice so far, and well done for having the sense not just to plug it in

Mine was full of perished rubber-insulated wiring and was a bit of a death trap when I got it, even though it was immaculate externally and was sold to me as a go-er. As David implies though, these make a perfect introduction to our hobby, and restoration is unlikely to be very difficult or expensive.

Originally Posted by Flecktarnfisher

I don't want to scrap the innards in case they work but they are so filthy and were slightly damp...

Modern Bluetooth/MP3/amplifier modules are so tiny that it would be easy to fit one inside the case, and connect it to the original loudspeaker.

You could disconnect the original chassis from the speaker and remove its mains lead, leaving it in situ for the time being, so that someone (maybe you) could restore it at a later date, if desired.

Nick.

[Voxophone]

Originally Posted by Flecktarnfisher

My main reason of buying it was to restore the case and build a small portable mp3/bluetooth amplifier within the case to take with us on car shows to play music through

If you intend to take the radio to shows etc. the availability of a mains supply could possibily be an issue. A small bluetooth/mp3 setup might give you more flexibility here, or you could derive an AC supply from an inverter.

[Flecktarnfisher]

Thanks chaps for your advice. I'd love to restore its innards but for the time being I think I shall restore the case and clean the internals ready for restoration in the future but for now I shall follow Nick thedentists idea and fit a small MP3 player module to it. I in fact have a small 8 ohmn 0.5 watt one I soldered up a little while ago which I will try fitting in to the case. Does anyone know if this will be enough to drive the original speaker if I soldered it in?
Many thanks for all your encouraging words!
Lloyd

[dj_Keet]

I was just about to take my AC41 (Which had been sitting in the porch for years) to the antiques shop until I read this post especially David G4EBT comments. Mine works but could do with replacing some of the components.

Thanks for changing my mind.