Philips FX824A Radiogram 1953

[baff1957]

Hi all, i purchased an old radiogram and is in very good condition, i was hoping it was going to work and we could enjoy is lovely tones so i thought i would take a go at getting it working although no knowledge of these old radios and never worked on one, i manufacture inductors and chokes as a business so not shy of a soldering iron.
It started by powering on and watching for any problems , all seem ok other than no volume or output, i checked the tubes for power and heaters functioning and the two tubes AZ41 sitting next to the transformer where not powering up so i purchased two new ones (see photo) and inserted into the board and they all lit up and i got some speaker crackle when i played with the volume knob.
I noticed a smell and the source, what i first thought was a transformer but as only a one wire in and out apart for a earth to chassis with a resistor it is possibly an inductor, i attach a photo. Obvoiusly there is probably a heavy load on it but it is attached to a fuse that has not blown just gets too hot as the bitumen is melting.
I found a manual in German but has not helped.
I want to get it working again so any help would be very appreciated.

Very Best Regards

David

[Edward Huggins]

Well, you've not chosen the easiest of Projects by far.....but even so, so its a beautiful thing - but may be a beast to service! Don't go rushing in to buying (expensive) valves. They may turn out to be the least of your problems. This must be one of the very first sets to use the EL84 and I think will have been built later than 1953. Probably from mid-1954. I'm sure Maarten on here may know more. Do you really have no experience of reading schematics, fault finding and voltage measuring?

[Station X]

I'm afraid that by applying power to this you've done the worst possible thing. Faulty capacitors costing a few cents can cause failure of major, expensive and difficult to get hold of components in vintage kit. Please don't plug it in again.

The failed component looks like the smoothing choke, but it will have failed due to failure of another component somewhere.

Is it possible you could post the circuit diagram here so that we can give further advice.

[baff1957]

Originally Posted by Edward Huggins

Well, you've not chosen the easiest of Projects by far.....but even so, so its a beautiful thing - but may be a beast to service! Don't go rushing in to buying (expensive) valves. They may turn out to be the least of your problems. This must be one of the very first sets to use the EL84 and I think will have been built later than 1953. Probably from mid-1954. I'm sure Maarten on here may know more. Do you really have no experience of reading schematics, fault finding and voltage measuring?

Hi yes i have some experience of electronics, self taught. I have a LCR bridge and can test capacitors resistors. I mange to repair modern circuit boards and as a winding company i can manufacture chokes and inductors and can wind transformers. I have a huge stock of Ferrite MPP and Iron powder Cores if anyone needs any.
I tend to google the fault and someone out there will point me in the right direction, i had some roller shutters that were very old but only rotated in one direction (down) which was not much use It turned out to be a capacitor 1uf which was reading 0.6uf.
The only problem is the only circuit board layout is in German and its a non translatable (machine) pdf and i struggle with it, also some of the components are weird. No idea of their function. I just have never worked on valve sets. thank you for your message, it is appreciated.

[baff1957]

Originally Posted by Station X

I'm afraid that by applying power to this you've done the worst possible thing. Faulty capacitors costing a few cents can cause failure of major, expensive and difficult to get hold of components in vintage kit. Please don't plug it in again.

The failed component looks like the smoothing choke, but it will have failed due to failure of another component somewhere.

Is it possible you could post the circuit diagram here so that we can give further advice.

Hi and thanks everso for your reply and offer to help. The only positive is the two valves faulty i replaced has now applied power to that choke so probably the reason the valves went in the first place.
I will upload the pdf repair manual. and many thanks for your help.

[Herald1360]

It's a beast all right!


Manual attached- sourced from NVHR via Elektrotanya!

[Station X]

The burned out component is S5 the smoothing choke which should have a resistance of 320 ohms. The fuse appears to be a later addition.

There are any number of reasons why it's burned out. Most likely failure of the smoothing capacitors C2 and C3.

As a matter of course you should replace the audio coupling capacitors C102 and C103. Failure of these could destroy the mains transformer, output transformer and the new output valves.

[dazzlevision]

The two manuals posted are in Dutch, not German.

[Michael Maurice]

Can you post a picture of the underside please?

[baff1957]

Originally Posted by Herald1360

Manual attached- sourced from NVHR via Elektrotanya!

Thank you, very helpful.

Originally Posted by Station X

The burned out component is S5 the smoothing choke which should have a resistance of 320 ohms. The fuse appears to be a later addition.

There are any number of reasons why it's burned out. Most likely failure of the smoothing capacitors C2 and C3.

As a matter of course you should replace the audio coupling capacitors C102 and C103. Failure of these could destroy the mains transformer, output transformer and the new output valves.

Thank you so much for this info, very very helpfull, C2/C3 , is that housed within a single aluminium housing? as i see i can is advertised as C2/3? also never seen these before , are they inside the enclosure? do i have to take the case off the wooden mount to get access?
is this what i need:-
https://www.ebay.fr/itm/Vintage-Sync...8AAOSwDPhc967F
Thanks again

Originally Posted by Michael Maurice

Can you post a picture of the underside please?

Hi, do you want me to remove from the wooden mounting? so you can see the wiring? again, many thanks

david

[Station X]

C1, C2 and C3 are all 50uF capacitors. C1 is in a can on its own and C2/C3 share a "dual can".

The nearest modern preferred value would be 47uF and the capacitors need to be rated at 450VDC, or perhaps there's a voltage rating engraved on the existing cans? You could fit the new capacitors on tag strips, obtain new can capacitors if available, or restuff the existing cans. Type restuffing into the Google Custom search box at the top of this page for more information.

The eBay item linked to is unsuitable as it's only rated at 200V.

[baff1957]

Thank you again, great information, i now have to investigate further and will report back.

[Station X]

Don't forget you'll need to find a replacement choke or get the burnt out one rewound. That shouldn't be a problem as I understand you can rewind transformers.

We don't know why the choke burned out, but failure of the capacitors mentioned in post #7 seems likely.

Measure the resistance between chassis and the points marked +, ++ and +++ in post #7 picture 1 to make sure there are no obvious short-circuits. Expect you meter to take time to settle as it will initially be charging the smoothing capacitors.

You could also check the windings of the mains transformer for continuity. If all is well remove the rectifier valves, disconnect the choke and measure the AC voltages on the secondary windings.

[Michael Maurice]

You can buy the correct capacitors here

Yes I’d like to see the layout of the underside of the capacitors as we can help you locate possible parts that need replacing.

[baff1957]

Hi, here are my readings C1 36.7uF C2 36.8uF C3 35.6uF (c102 68.6nF and C103 40.8nF, diagram says 33nF ??).
The smoothing choke has a resistance of 447ohm and an Inductance of 4.6H
All tested removed from chassis.

Is there sufficient deviation as tolerances are not printed on the Caps?

Again Many thanks.

David

[Station X]

The thing about capacitors is that they leak electrically, in other words they turn into resistors. The only sure way of testing for leakage is to apply the full working voltage, gradually of course, and measure the leakage current.

Leakage can in itself cause incorrect capacitance measurements.

You could build a capacitor reformer or perhaps you have a variable voltage power supply capable of supplying the full working voltage?

http://www.vintage-radio.com/project...-reformer.html.

[baff1957]

Originally Posted by Michael Maurice

You can buy the correct capacitors here

Yes I’d like to see the layout of the underside of the capacitors as we can help you locate possible parts that need replacing.

Ok, will upload some pics.

[Station X]

The yellow cap is obviously not original, so someone has already done some work on this.

The black tarry caps look pretty nasty and will ultimately need replacing.

[Michael Maurice]

The black tarry caps are as bad if not worse than the waxies and the Hunt’s moldseals. In other words replace on sight!

[baff1957]

Originally Posted by Station X

The thing about capacitors is that they leak electrically, in other words they turn into resistors. The only sure way of testing for leakage is to apply the full working voltage, gradually of course, and measure the leakage current.

Leakage can in itself cause incorrect capacitance measurements.

You could build a capacitor reformer or perhaps you have a variable voltage power supply capable of supplying the full working voltage?

http://www.vintage-radio.com/project...-reformer.html.

Hi Graham, thank you for this, i appreciate your help, i think without question i will fit new as i have removed them and just not work the risk and if it gives me another 57 years i will be happy, lol