EL41 tube

[inecik38]

Dear friends ,I have restored a telefunken jubilateS radio (small cabinet).I want to learn that:radio has these tubes ,ECC85,ECH81,EF89,EABC80,EL41 and EM80.for me EL41 tube has much heat from all of another tubes and cabinet .it is normall ?
inecik

[Darren-UK]

Hi Inecik,

The EL41 is an Output Valve and most o/p valves run hotter than other valve types.

However, you need to determine if the EL41 is indeed running at its normal temperature.....or if there's a fault causing it to overheat beyond this. After the radio has been running for a while, it (the EL41) should be too hot to touch for any longer than a few seconds.

Presumably you checked voltages around the EL41 ? and is the radio apparently running normally with no suspicious smells or smoke?

[geofy]

Also check that only the heater is glowing and not any other part of the valve. Is the sound normal or distorted, is the output transformer getting hot, if so the set should be switched off and the cause investigated. A substitute valve could be used to compare.

G

[inecik38]

Dear darren I don't know how to check voltage araund EL41 ...

[Station X]

Have you changed the capacitor feeding the grid of the EL41? If not do do now or you run the risk of destroying the output valve, the output transformer and the mains transformer.

[jim_jobe]

I don't think I could touch a hot EL41 for more than a few milliseconds!

Originally Posted by darren-uk

After the radio has been running for a while, it (the EL41) should be too hot to touch for any longer than a few seconds.

Jim

[paulsherwin]

Originally Posted by jim_jobe

I don't think I could touch a hot EL41 for more than a few milliseconds!

Indeed. These valves run too hot to touch in normal operation, and will be *much* hotter than the other valves in the radio. This is normal and doesn't indicate a fault.

You should check the grid coupling capacitor though, as has been suggested. In fact you should check that all the voltages around the valve correspond to those given on the circuit diagram. You should do this with any radio, even if it seems to be working normally.

Paul

[GJR 11L]

An EL41 among that line-up seems odd, just about every other similarly-equipped set that I can think of has an EL84 doing the audio output work.

Now, this is more likely a simple case of my not having met this model than a problem, but a little rimlock jobbie among B9s? Is this even the correct valve and base for the set?

I have a couple of different Telefunkens of the period with the same line-up, both use an EL84.

[paulsherwin]

Originally Posted by GJR 11L

An EL41 among that line-up seems odd, just about every other similarly-equipped set that I can think of has an EL84 doing the audio output work.

Some manufacturers did use a mixture of B8A and B9A valves in the second half of the 50s, presumably to use up stock. The valve bases are the same size so it was possible to switch valve types during a production run if necessary.

Paul

[Steve_P]

Right - first, have a read...

http://www.vintage-radio.com/repair-...ut-stages.html

If the capacitor everyone mentions is leaking onto the Grid of the output valve, then bad things will happen. Change it. In the second diagram it is C54. There may or may not be a resistor in there as well.

Other things to check - the voltages between Valve and Chassis are:

Pin 2 - 170v or thereabouts. This is the valve anode.
Pin 5 - 170v or thereabouts. This is the Screen Grid.
Pin 6 - Control Grid.Anything positive here after the cap has been changed is a valve fault. You may be able to live with it.
Pin 7 - Cathode. Should be a low voltage. Depends on the set - read from the manual.

You might have a Resistor and Capacitor here. Read the value on the resistor and change the cap if you aren't sure about it.

The valve has a pin to locate it in the socket. With the valve pins facing you, count round from the pin to the left of this pin. This will give you valve pin numbers.

Cheers,

Steve P.

EDIT: I've got a Turkish Valve Set on the bench right now actually. It's all B9A except for the O/P valve, which appears (no print on it) to be an EL95. So it is possible for there to be mixtures of valve bases.

[vahakuja]

EL 41 is the correct tube for original Telefunken Jubilate S 1955/56. But some later models utilizes EL 84.

Reagards
Ake

[XTC]

Originally Posted by Steve_P

Pin 7 - Cathode. Should be a low voltage. Depends on the set - read from the manual.

You might have a Resistor and Capacitor here. Read the value on the resistor and change the cap if you aren't sure about it.

The valve has a pin to locate it in the socket. With the valve pins facing you, count round from the pin to the left of this pin. This will give you valve pin numbers.

inecik38,

You can check the screen and anode current through the valve by measuring the cathode resistor (probably 180R), then measuring the cathode to chassis voltage (probably 6 to 7 volts) then applying Ohm's Law to the cathode resistor. Check the resistor again when the set has been switched off, but it's still warm.

The cathode bypass capacitor, if fitted, could be leaky.........

Have a look at the service sheet for this set, but if it's more than 42mA you've got a problem with the valve being overrun for some reason. With 170V on the screen and anode, I'd expect the current to be less than 35mA - look at the service sheet.

Anyway, it's not clear from your original post whether you think the EL41 is running hot for an EL41, or whether you think it's odd that it's much hotter than the other valves. In a healthy set, the EL41 would produce more heat than ECC85,ECH81,EF89,EABC80, because it's a power valve in an envelope of approximately the same size as the others, but with more than twice the heater current and at least three times the cathode current.

Pete.

[inecik38]

Dear friends ,
heater is glowing
sound is normal
no smoke.
I think that:EL41 much hotter than other valves and I can't replace C46 cap( it is a metal cap) is it cause of fault ?
please write me simply that: how to measure voltages araund valve?

[Station X]

C46 is the cathode bypass capacitor. The capacitor you need to replace is that connected to pin 6 of the valve.

To measure voltages connect the black lead of your meter to earth and use the red lead to probe pins 2, 3, 5, 6 and 7 of the valve in turn. Report results here.

[Nickthedentist]

Originally Posted by Station X

To measure voltages connect the black lead of your meter to earth and use the red lead to probe pins 2, 3, 5, 6 and 7 of the valve in turn. Report results here.

Exactly. Make sure you don't accidently join any of the valve pins together with the red probe, and make sure that your meter is switched to a high enough range (maybe 500V one).

Nick.

[inecik38]

Hello everyone ,I measured voltages araund valve.
pin 3: 3-4 volt DC (Cathode)
8-10volt AC
pin 7: 4 volt DC (Cathode)
pin 2: 223 volt DC (Anode)
480 volt AC
pin 5: 204 volt DC (Screen)
445 volt AC
pin 6: ZERO volt (Control Grid)

I have another question. C45 cap is the grid coupling capacitor? if it is Ok I replecamend it before.that schema is orjinal circuit
my set.

[Steve_P]

Looks OK to me does that. Pin 6 is 0 Volts. That's the main thing. Check W27 on your diagram (250 Ohms) to be sure.

1) Switch off set.
2) Switch meter to Ohms Range.
3) -ve to Chassis.
4) +ve to Pin 3 of valve.
5) Give a few seconds for the cap to charge up.
6) Read Value.
7) Swap meter leads round : +ve to Chassis, -ve to Pin 3.
8) Give a few seconds for the cap to charge up.
9) Read Value.
10) If it's higher than say 270 Ohms, change it.

These valves do get hot. Don't worry too much about it.

Cheers,

Steve P.

[inecik38]

thanks everyone .
inecik38