Hi Everyone,

I purchased an AWA Radiloa 469-MA today. It was working really well with great sound and easy tuning, all I had to do was repair the clock which was a relatively easy fix. However when I left it to fun by itself, it stopped working. All the valves still light up, but turning the tuner has no effect, nor does adjusting the volume. All I get is a low hum from the speaker. It was running great and then, this happened after about 45 minutes. Where would be a good place to start looking?

Thank-you for reading.

Take care,

Jay.

I may be a bit hasty here, but I'd look at the electrolytic filter caps first.

To expand on #2, hum as you describe it signals failed filter capacitors in the power supply. The electrolytic capacitors in radios of that vintage are way past their use by date and need replacing, as do any original paper capacitors, and resistors need checking, too.

It's never a good idea to power-up vintage equipment without it being first checked over for a raft of usual problems, some of which can destroy the set unless attended to before power is applied.

Hi Robert and GTC, thank-you both for your fast replies and advice. There is one large paper covered electrolytic capacitor connected to the power supply. From what you are saying, am I right in thinking that this one could be one of the problems?

Here is a link to the picture of the under side of the chassis:



Please forgive me if my questions seem basic, I am new to repairing and am learning along the way. Is this large brown paper electrolytic capacitor a filter capacitor?

Thanks again.

Jay

The paper-covered one is indeed one of the two filters capacitors. The other is the grey one up and to the right of the paper-covered one. It would be best to replace both.

First up, the capacitor you describe, plus the grey one above it should be replaced. Note that the new equivalents are about half the size and this is normal. Don't go below the working voltage ratings or the new capacitors will go bang. Don't be too tempted to stray too far from the capacitances either, too low and the mains hum will remain and too high will ruin the rectifier valve.

Secondly, it is recommended that all the smaller black capacitors be replaced. They too have a high failure rate after 50 years or more on the job. Member Carl Tallar can assist with the supply of suitable replacements. Once you have made a list of the capacitors you need, e-mail Carl for a price.

Obtaining a circuit for this set is a good idea if you don't already have one.

Thank-you Robert and Brad.

Those two capacitors both have values printed on them. The grey one has "24 MFD 350 V.P. Type ET5C" and the brown one has "24 MFD 350 PV Type ERJ". As Brad said, I do not want things to go "bang", so what would be a suitable replacement for these two?

I will certainly see if I can get in touch with Carl.

Thanks guys.

I think the closest value is 22μF (MFD) these days and that is fine for both these capacitors. Again it is worth checking with a circuit diagram to make sure they are the correct values. They seem to make sense but nothing in a valve radio is 'normal' and capacitor values do vary between models, some to a great degree. Don't go below 350 volts - 450 would be better to provide some headroom for longer term reliability.

I would also recommend replacing the power cord with a double-insulated one. The existing one looks okay from the photo however single-insulated cords can cause problems down the track. Some power transformers have unused voltage tappings on models that were exported to Asian countries. Some members recommend taking photos before disconnecting anything so you can be certain of where replacement components belong. It's easier than trying to remember.

Thank-you very much for your help Brad, it is greatly appreciated.

There is rubber wire under the Black cap at the bottom, it is deteriorated and has to go, some of the wiring is new. That mains cble just has to go and tying a knot in it is now illegal. Depending on the cabinet that hole on the LH side is a candidate for a "gland" pointy end inwards.

You will note: that typical of that type, some of those black caps have cracks in the jacket. That can see them ingest moisture and I have seen them snap off & short. The Yellow axials of 630VDC are the universal replacements.

If you are totally unsure about this, sub let the contract to some one who knows how to fix it.

Closest circuit is 461MA only the 469 has a ferrite antenna 24μF is correct for filters. Watch it as that is back biased & the first filter does not go directly negative to ground (chassis) it goes to the transformer centre tap.

Marc

If you are totally unsure about this, sub let the contract to some one who knows how to fix it.

This is good advice. Lethal voltages are present in valve radios.

http://www.kevinchant.com/uploads/7/1/0/8/7108231/469-ma.pdf

Hi CGBSpender I do have these Caps available I recommend you get all the caps replaced except the micas. The Electros are 3.50 each and the others are 35 cents each plus postage. My email is unhidden . Marcc is correct in his advice to get a pro to do it but I am happy to help you out if you want.
Regards Carl
Thanks Brad.

I can also supply you with a appropriate cloth covered cord with a moulded plug on the end. That power cord you have there is dangerous and illegal.

What I have done with cloth covered wire is put shrink tub over it & perhaps Acrylic adhesive (beware of heat on cloth coating) and use a gland. That eliminates the possibility of the cloth creeping back.

I may have a photo, as the last radio I did that too, was commercial fix; it came in & went out swiftly.

Marc