Clarson Artois (French) 1950's Caps question

[Wishiknewmore]

Hello

As I was about to order a batch of capacitors I decided to open up another set and get some parts in readiness

This set is about 1951, valve line up EZ80,ECH42,EF41,EBC41,EL41 and EM34.

The radio has been repaired in the past, with a new tone control pot and three new caps,

The first replacement is a 50uf from the cathode on the EL41 to ground in parallel with a 150 ohm resistor

The second is a 25uf from cathode on the EBC41 to ground in parallel with a 5k ohm resistor, my concern I that they are both rated at 9v, does this seem correct?

The third is a 0.047uf 630v connected from the wiper on the tone control to the anode on the EL41, I guess that seems ok.

There is also some wiring mods as well, but as I can’t find a circuit diagram, I am (or will be) at a bit of a loss.

My question at this stage what should the voltage ratings be?

I have fired it up on the lamp limiter, dial lamps light, both AC and DC HT voltages but just get a major hum!

Philip

[HamishBoxer]

47 and 22uF are replacements,9 volts can not be right try 25Volts at least and check what voltage is across them.Hum could be main smoothing caps shot.

[Walterh]

Hello Philip

As you already fired it up, i think you have set it to the right voltage (many french sets worked on 120 V).

Then search for the cap between pin 2 (a) of the EBC41 and the pin 6 (g1) of the EL41. It will be in the range of 0,01 - 0,02 uF. Replace it. There will also be a resistor in between - on g1 a 1 kOhm, the grid stopper.

Then i see a screw mount electrolytic. Not clearly visible, but i guess 2 x 50 uF. These are the load and smoothing cap of the power supply. If they lost capacity, they will cause hum. For a test you can bridge them one by one using new electrolytics. Check for same or higher working voltage - probably around 450 V.

Good luck, Walter

[Wishiknewmore]

Thank you gentlemen
I fired it up just to see if the transformer were still with us and without the EL41, then curiosity took over and gave it a try with the output valve in!
My plan is to replace the electrolytic and paper caps
HamishB has confirmed my suspicions about the 9volt ratings

Walter, The load smoothing caps are indeed 50uF 350/400v, replacements are on order(47uF 450v), the cap between pin 2 on the EBC41 and pin 6 on the EL41 is a glass covered 50,000 pF(physically leaking) in series with a 10k ohm (reading11.7k) and at the junction of the cap and 10k resistor there is a 500k (reading720k) to ground.
I suspect that the 50000pF cap may have been replaced at sometime as a more modern orange covered wire extends its leg, so do you think its rated value may be high, or replace it with similar ie 47nF?

Thanks again
Philip

[Herald1360]

The 50,000Pf coupling cap sounds like a reasonable value, so 47nF will be fine as a replacement. The 10k (11.7k) stopper should be fine, its value isn't particularly critical. It would be sensible to replace the 500k (720k) grid leak, though. 470k will be fine for this.